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Chapter 12: indoor plants.

KEY TERMS

forcing interiorscaping understory

The earliest experiences many people have with plants involve indoor plants. Indoor plants have been extremely popular at various stages in history, which has led to the popularity of inventions such as the terrarium and self-watering pots. During Victorian times, large ferns and other potted plants were favorites. With increased urbanization and the advent of modern high-rise buildings serving as homes and offices, people have included plants in their lives by bringing nature indoors where they spend much of their time. The profession of interiorscaping has grown as a result of this trend (Fig. 12-1). Taking care of indoor plants begins with understanding the needs of individual plants and learning how best to provide them (Figs. 12-2 and 12-3). Table 12-1 lists various types of houseplants and some of their basic requirements.

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Foliage plants suitable for indoors perform so well because of the environments they evolved in. Many were initially collected from the understory of rainforests where light levels can be quite low (Fig. 12-4, see page 209). The understory consists of young plants of canopy trees, some shrubs, and herbaceous plants.

People enjoy plants indoors for their aesthetic value, but plants also are good for the environment. They take up carbon dioxide and give off oxygen, of course, but many houseplants do much more: they clean up pollutants in the environment. Chemicals, such as formaldehyde, that are given off by furniture and carpeting are removed from the air by many houseplants. (See Table 12-2 for plants and the pollutants they remove.) One potted plant per 100 square feet of floor space is enough to help clean the air in the average home or office. More plants would increase the rate of pollutant removal. Indoor plants also bring beauty and nature indoors. In this respect, they have a positive impact on people's attitudes and moods.

Growing plants indoors requires special consideration in all areas of plant culture: lighting, soilless media, temperature, and humidity. Pest and disease control methods will also probably vary from those used for outdoor plants, whether in the home environment or on a larger scale in an office, hotel, or shopping center. Fertilization techniques will be similar to those for other container-grown crops, but timing will differ because of the different growth habits inside a home or other building compared with growth in a greenhouse. Finally, it is helpful to consider the origins of the houseplants you wish to grow. The more closely you can replicate the natural conditions in which they evolved, the more successful you will be growing them in your home. Temperate and tropical areas both experience changing seasons. In temperate areas, these seasons are vastly different, with regard to changing temperatures, daylength, and precipitation. However, in the tropics, daylength varies little to not at all, and the seasons change between rainy and dry, and there may be only 10-20[degrees]F differences in temperatures. You may need to replicate these conditions to provide dormancy periods or simply to allow the plant to experience its natural cycles throughout the year.

LIGHTING

A major consideration when deciding to grow plants indoors is light. Most homes have very low levels of light, with perhaps only a few percent of the amount of light outside on a sunny day. Even when a plant is placed in a sunny window, the light is often inadequate to support its growth. Sunny windows still generally only receive direct light for a few hours a day, if at all. Therefore, the success of plants that have become familiar houseplants is due precisely to the fact that they can survive and even grow in low light conditions. Thus, plants for the indoor environment should be selected for the light level that is available. Plants and their optimal light levels are listed in Table 12-3.

Sun Exposure

Rooms in a home provide differing levels of light, depending on their orientation to the sun, which moves throughout the day and throughout the year. East-facing windows provide sun in the morning, which is considered a good time of day for plants to receive light because it has a positive effect on photosynthesis. After the long period of dark, during which existing resources for energy have been used for respiration, the plant requires additional photosynthates for optimal growth. Accumulation of the photosynthates begins as soon as the plant receives the light energy required for photosynthesis.

South-facing windows may provide sunlight throughout the day, if there are no obstructions from outside. Often this light will be direct. In the Northern Hemisphere, north-facing windows will not provide much direct light at all. In summer, some direct light may come in from the north in the early morning or late afternoon because of the angle of the sun. Any overhang on the house will further reduce the amount of light that enters. Plants that are placed near north-facing windows or in locations where they do not receive any direct light must be well-adapted to low light levels. Figure 12-5 illustrates light levels at different windows in the house. West-facing windows receive sunlight late in the day and during the warmest part of the day. If your house or building is air-conditioned, the warmth from windows will not have much effect.

Before placing a plant at any particular window, observe the length of time a window receives light throughout the day and how much direct sunlight enters the window. Be aware of the changing angle of the sun throughout the year, noting that it will be lower in the southern sky in the winter. Take note of outdoor features such as walls, fences, shrubbery, trees, and overhangs that may interfere with the sunlight. These observations will provide some guidance as to the type of plants you can place at various locations inside the house.

Artificial Lights

Although many houseplants are used primarily for their foliage, some houseplants will also produce flowers. Geraniums, orchids, cyclamen, and camellias are just a few flowering plants that are grown indoors. Many flowering plants require higher light levels to produce flowers. If the plants you wish to grow require higher light levels than are available in your home or building, then you should consider setting up special lighting.

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You can address the lighting problem in a variety of ways. One is to purchase a small grow-lamp and place it in a corner of the room with a single plant. Another is to construct a special room with racks of shelving for plants and banks of lights over each shelf. Other options fall in between these two extremes. All of these options have been used and serve the purpose for which they were intended. Orchid lovers, for example, may construct a special room in their home, convert a basement into a plant-growing room, or install lighting in a bathroom or spare room of the house to provide the conditions required for their plants to thrive. The key to success with artificial lighting is to understand the quality and quantity of light provided by the lamp you intend to use. See chapter 7 for a discussion on artificial light sources.

TEMPERATURE

The temperature inside a home does not fluctuate as much as the outside temperature. As temperatures rise, plants utilize stored foods through respiration at an increasing rate. Therefore, if a plant is in a warm location, it will require a higher light level, as well as more water and fertilizer. Every house has its own temperature conditions, and these often vary from room to room. Temperatures often vary inside the home throughout the year. Therefore, it is important to understand the needs of the plants you are trying to grow and place them in the proper environment in your home. To be most successful, you may not be able to grow certain plants if your home cannot provide the proper temperature ranges.

Sometimes household temperatures are too cool for plants, especially in a cool basement or near windows. If a plant is too cold, you may notice older leaves becoming limp, turning yellow and dropping off. Flower bud blasting and new leaves that are smaller than normal and slightly curled are other symptoms. Revive such plants by moving them to a warmer location.

Forcing

Some plants may require cool temperatures or even chilling (see chapter 7 for a discussion on chilling) for initiation of flowers. Such plants are normally considered outdoor plants, and these include tulips, daffodils, and hyacinths. However, by providing the chilling requirement for floral buds to complete their development, you may grow these bulbs indoors, providing flowers in the middle of winter. This is a process known as forcing, which refers to providing the proper environmental conditions for flower formation to occur without waiting for natural events to take place. This generally requires providing cool temperatures for a specified period of time. Bulb forcing is a science that was studied by Dr. Gus De Hertogh in the 1960s (see box).

In temperate climates, winter is never over soon enough. This fact helps explain why florist shops are full of spring-blooming bulbs for Valentine's Day. But anyone who knows the secrets of flower development in bulbs can recreate this welcome sight in his or her own home by using the following procedure, which requires very little special technology or equipment. Bulbs that readily respond to this treatment include daffodils, paper whites, narcissus, hyacinth, crocus, and grape hyacinth (Muscari). Tulips are more challenging, usually requiring two or more stages with different temperatures at each stage. Specific tulips have requirements that are maintained as trade secrets by bulb producers.

If you want to force bulbs, begin by attaining high-quality bulbs of the desired species. Check to make sure they are not dry or shriveled and do not have pest or disease damage. Plant the bulbs in pots containing potting soil, with their noses pointed upward and emerging a bit from the soil. They should be planted fairly close to each other or even touching. Water them in and do not allow the soil to dry out throughout this entire process.

Place the potted bulbs in a cold place, such as refrigerator, unheated attic, garage, or cellar, about 35 to 45[degrees]F. Do not allow them to freeze or they will be destroyed. Allow them to remain in these cool conditions for 12 to 13 weeks (see Table 12-4 for specific requirements). Once the shoots begin to emerge you will know it is time to remove the potted bulbs from the cool conditions and begin providing warm conditions. You can achieve this by simply placing the pots at room temperatures indoors. Water as you normally would. Room temperatures above 55[degrees]F are adequate to encourage leaf and flower emergence. The cooler the temperature is, the longer lasting the flowers will be. If plants stretch too much, they are not receiving enough light and should be moved to a lighter or sunnier location.

To have blooming plants when you like, time your starting date to the desired bloom time. Bulbs will bloom in about 4 weeks from the time they are removed from the cool conditions. Bulbs cannot be forced a second year and should be planted outdoors after flowering. Hyacinths and tazetta narcissi will grow in water alone. Purchase special vases designed to hold the bulb above the water level. Amaryllis is a tropical plant and does not require chilling. Under natural conditions it responds to a moist and dry period. Amaryllis bulbs are often sold as a Christmas gift because of the ease with which they bloom indoors.

HUMIDITY

Many house plants originated in humid tropical climates, whereas others, such as cactus, evolved in arid climates. Houses tend to be dry, especially in winter when they are heated, but also in summer, when air conditioning is used. Air conditioners remove moisture as they cool the air. Special efforts may be required to create conditions for plants that thrive in humid environments. Some plants may be placed in a bathroom, where humidity is high at some times. But not all bathrooms have ample space or lighting for this to be a practical solution. Humidifiers can be a good solution, because there is some evidence that dry air leads to more colds in the winter, and, thus, humidifiers can be beneficial to both plants and humans. Although it is a bad idea to allow a plant to remain in standing water, it is permissible to place a saucer filled with water and a layer of pebbles under the pot. The pot should stand atop the pebbles without touching the water, and this will increase the humidity around the plant (Fig. 12-6). Check the water regularly and refill as needed. Misting plants regularly with a spray bottle is also beneficial.

MOISTURE

Houseplants vary in their requirements for moisture. The best way to control the moisture level for plants is to use appropriate soil or soilless media. For plants that prefer dry soil, use a better-draining, less moisture-retentive medium such as a sandy mix or a mix with higher levels of perlite. For moisture-loving plants, include some natural soil with clay in it. Vermiculite can help with moisture retention, too.

Watering Techniques

Although some houseplants require more water than others, overwatering is the leading cause of houseplant death. The amount of watering required varies by the type of plant, the type and size of the pot, the type of soil or soilless media, temperature and humidity, sun or light exposure, and time of year.

Larger pots will retain more water than small pots, but if the plants in them have a well-developed root system or large leaves, they may still lose water quickly. Shallow pots stay wet longer than deep ones because of the reduced gravitational pull on excess moisture. Thus, it is not a good idea to add rocks to the bottom of a pot to "improve drainage," as some sources suggest. Adding rocks actually reduces soil depth, resulting in slower draining. The best way to improve drainage is to add sand, perlite, or another coarse material to the soil or soilless medium. Shallow containers and poor drainage can be a special challenge in the case of bonsai plants (see box). Use a well-draining medium with small-sized gravel to help alleviate this situation. Unglazed clay pots are porous and lose moisture through their sides. Plastic and glazed clay pots retain water better (Fig. 12-7).

Plants on a sunny windowsill will grow faster than those with less light exposure. They may also heat up, resulting in water loss from the medium by evaporation. The higher humidity in bathrooms will contribute to reduced moisture loss. Plants should be checked daily for moisture status. As they grow and become larger or have more leaves, houseplants will require more water. If plants are drying out faster than usual and it is difficult to keep them adequately watered, it may be time to place them in larger pots.

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Soil has clay in it, whereas most soilless media or potting soil mixes are composed largely of organic matter, such as peat moss or decomposed bark or compost. Clay retains water and to make up for this characteristic in soilless media, vermiculite is used. Perlite is often used to increase porosity and improve drainage so plants do not remain wet too long. Too much soil in a container-grown plant can result in a hard, compacted medium that does not drain well and is not optimal for plant roots. However, as plant size and container size increase, it is more desirable to add soil to the soilless medium. It can provide better moisture-holding ability and also makes the pot heavier and less prone to tipping because of being top-heavy. Plants that are growing outdoors in containers can also benefit from the improved water-holding ability of soil. They have a limited supply of soil moisture compared to plants growing in the ground. Keep the added soil to a minimum, and remember that the larger the container is, the more soil that can be safely used, but for best results do not exceed a 50-50 blend of soil and soilless media.

Yellowing mushy leaves are an early sign of overwatering. These leaves are often mushy because of the excess water in the cells. They will turn brown and drop off or simply drop off while still yellow.

Allow plants to dry somewhat between watering but do not allow them to remain dry for more than 1 or 2 days. When watering, be sure to moisten the entire root ball. This can be difficult to do, as channels develop through the root ball, and often water runs out through the bottom of the pot before the entire root ball is moistened. A good way to avoid this runoff is to submerge the entire pot in a bucket or other container filled with water. Keep the pot submerged until air bubbles no longer escape.

Place saucers or trays under pots to capture excess moisture. However, excess moisture should be promptly removed so the plants are not standing in it. Some plants do not tolerate wet leaves or watering from the top of the soil. Notable among these are the African violet and cyclamen. Water these plants from the saucers or trays placed under the pots. Allow the moisture to wick upward through the soil. Watch the plants closely to prevent them from remaining in standing water too long. Allow 5 to 10 minutes for the water to wick up from the plant tray. Empty the excess water when moisture has reached the surface of the media.

Proper Container Drainage

Containers used for houseplants must allow complete drainage of water out of the base. Avoid ornamental containers that lack drainage holes. There are two solutions if you must use an ornamental container that lacks at least one hole. One is to set the plastic pot containing the plant inside the ornamental pot. Remove the plant when watering, to allow excess water to drain completely away. The other solution is to drill at least one hole in the base of the ornamental container. If the hole in the base of the container is too large and permits soil to escape from the pot, you may place a piece of pottery shard or medium-mesh screen over the hole.

SOILLESS MEDIA

The quality of potting soil purchased at garden centers and nurseries varies greatly. Some media are excellent all-purpose mixes, whereas others are muck-like. The latter may appear dark in color and may even be crumbly when dry, but when wet, they become a clayey mass with small pores that do not drain well. They may lack a variety of particle sizes and thus are poor media for use in container-grown plants.

The ingredients in potting soil, or soilless medium, as it is sometimes called, should be labeled on the bag. The major ingredients used in good-quality potting soil are peat moss and/or compost, perlite, and vermiculite. Peat moss and compost are organic media that provide aeration and a large surface area for moisture and nutrient storage. Perlite is an inorganic medium created by heating a mineral that is of volcanic origin. Perlite particles are relatively large and provide drainage in soilless media. Vermiculite is a layered clay that swells like an accordion when water is available. It has also been heated to high temperatures. It retains water well, while making moisture easily available to plant roots.

The ratio of different soilless media ingredients determines how well-draining and how moisture-retentive it will be. Commercial mixes are available for different purposes. Seed-starter medium has higher amounts of vermiculite. Mixes for larger container plants may include larger particles, such as partially composted bark. These provide better drainage and reduce compaction that can occur with smaller particles over time.

FERTILIZING

Fertilization requirements of houseplants vary, depending on whether or not they bloom, how fast you want them to grow, the media in which they are growing, and the species grown. Fertilizers contain three main ingredients: nitrogen, phosphorus, and potassium. These and other plant nutrients are discussed in detail in chapter 6. Nitrogen contributes to green vegetative growth and is helpful for plants that are grown for their foliage. Phosphorus aids in flower and fruit development and is used to encourage blooms and fruiting. Special bloom-enhancing fertilizers often have an increased level of phosphorus compared with levels of nitrogen and potassium, such as 10-60-10, 3-12-6, and so on. Potassium is useful for root growth, but this is not normally a concern with houseplants as it is for some vegetable root crops.

Houseplants typically do not require a great deal of fertilizer. This is primarily because they are grown under low light levels. If you keep in mind the fact that the main limiting factors for growth are light, temperature, water, C[O.sub.2], and fertilizer, then it makes sense that plants grown under low light conditions are not going to require much fertilizer or water either. Therefore, if you fertilize heavily, the result may be salt buildup and burning of the roots caused by overfertilization. A good rule of thumb for most houseplants is to fertilize during the growing season and allow for a rest period in the off season. However, if conditions inside are fairly constant throughout the year, then occasional weak fertilizing will suffice.

Some exceptions to the rule of fertilizing lightly are flowering plants that may require higher levels of fertilizer for flowers to form, such as geraniums, or plants that flower in response to higher levels of phosphorus, such as African violets. Other plants may flower better when grown under low-fertilization conditions, whereas still others flower in response to higher light levels. The latter plants will flower more often under moderate to high light levels than under low light levels, but the foliage will be fine either way.

Because houseplants tend to remain in the same container for years, there are two common types of fertilizer: water-soluble and time-release capsules. Water-soluble fertilizers may be applied with watering, and the amount can be adjusted depending on the light level. The usual recommendation is to add 1 teaspoon per gallon of water and water with this solution every 2 weeks. Time-release fertilizers are applied at rates determined by the size of the pot. Common rates include 1 teaspoon for a 6-inch pot and 1 tablespoon for an 18-inch pot. Cacti and succulents may require only half the usual rates. Time-release capsules are designed to last for several months, although more fertilizer will be released as watering and temperatures increase.

GREENHOUSES AND OTHER STRUCTURES

Greenhouses provide a sheltered environment that can extend the growing season or allow for year-round enjoyment of foliage plants and flowers. Greenhouse structures range from simple plastic-covered hoop houses, to three-sided home additions, to high-tech automated, integrated, computer-controlled feats of engineering. The options for greenhouse structures are as diverse as one's imagination and ability to adapt the available materials and technology. Of course, predesigned kits are available for many different situations. Although a greenhouse addition can be a costly undertaking for the average homeowner, the resultant ability to grow plants throughout the year and to extend the growing season can provide much pleasure and enjoyment. This section will focus on greenhouses for the typical homeowner rather than state-of-the-art greenhouses available for commercial production.

One important factor in deciding what kind of structure to build onto the home is energy use and cost. It is more efficient to attach a greenhouse to an existing structure than to build a free-standing unit. Whereas the obvious assumption is that heating costs will be high in winter, cooling costs in summer or in warmer climates could also be quite high. The goal of a good design is to minimize these costs. Some ways to do that include using an earth-sheltered design, collecting solar energy in water barrels or containers of rocks, providing heat close to the plant root zone rather than heating the air, and proper orientation of the structure.

Orientation

A greenhouse can be oriented either east and west or north and south. In general, at latitudes below 40[degrees] the orientation is not crucial to good growing conditions. However, north of this latitude, an east-west orientation is recommended. This orientation maximizes sunlight, particularly during the colder months when the sun is lower in the sky. The angle of the south-facing roof should be designed to maximize sunlight during the shortest day of the year. This angle changes with location (see chapter 7 and Fig. 7-13).

Heating and Cooling

A home greenhouse can be heated with passive solar heat, with a space heater, or with hot water from a dedicated hot water heater. The hot water may be piped into the ground or underneath beds. There are even specially designed mats for running hot water under plants directly on the bench. Solar energy can be collected in water barrels, and home greenhouses can be partially earth-sheltered to reduce heating costs in winter.

Cooling can be active or passive. Passive cooling is accomplished using vents. Active cooling is accomplished either with vents and fans or with evaporative cooling coupled with the use of vents and fans. The evaporative cooling unit is a separate unit that would be installed on the ground outside the greenhouse. It is more effective in dry climates than in humid ones, as it works on the principle of adding moisture to the air to absorb heat.

Because the basic concept at work in greenhouses is the trapping of light energy that becomes heat energy inside them, one effective technique for cooling the greenhouse is to reduce the amount of light coming in. This is done by covering the entire structure with a woven shade-cloth material. Shade-cloth is available in different levels of shading, from 22% to 90%. Instead of placing it over the entire structure, it can be used over individual benches. Cooling can also be achieved using a mist or fog system. This is a type of evaporative cooling, so the lower the humidity, the better it works.

Benches

If you are going to start seeds in the greenhouse or grow plants in small pots, you will want benches that can bring the plants to about waist level. The benches should be wide enough to reach across, or about 3 to 4 feet wide. If you are growing woody plants in larger pots, then benches may not be needed. If you wish to grow plants in-ground, then growing beds would be more appropriate. With proper planning, it is possible to design the greenhouse for a combination of plant sizes, having benches for some and ground beds for others.

Lighting

People often have dreams of growing tomatoes or other favorite foods in their greenhouse on a year-round basis. This is possible if there is ample light in your region. However, tomatoes, in particular, are a high-light plant and will probably require supplemental lighting in winter in low-light regions. Although the plants may grow throughout the winter, they probably will not produce flowers or fruit without supplemental lighting. Other plants also have high light requirements. Many flowering plants, including geraniums, bougainvillea, roses, and others require supplemental lighting to flower out of their usual season. See chapter 7 for a discussion of lighting. Supplemental lighting for plants is provided with specially designed, high-intensity discharge (HID) lamps. Incandescent lamps may be useful for photoperiodic plants but are not adequate to provide supplemental lighting for plant growth. Fluorescent lamps can be quite useful as supplemental lighting, although they do not provide as great a range of wavelengths as HID lamps do.

Watering Systems

Although many people prefer to water their plants manually because they can watch for changes or problems, automatic watering systems are available and fairly easy to set up. They can save time by allowing all the plants on one system to be watered simultaneously. Pots can be individually watered using spaghetti tubing that attaches to a main water hose, or an entire bench or bed can be watered with sprinklers on a mist system. An advantage of watering plants individually is that the water goes directly where it is needed, so less water is used or wasted. If plants require different amounts of water, zones can be created with a separate watering system for each. For example, plants in different sized pots, seedlings and mature plants, or those in ground beds will require a different amount of water. Also, in a very large system in which water pressure is an issue, it may be necessary to water plants in individual zones, one at a time.

Watering systems can be set up on a timer, but this is only recommended if the plants use a predictable amount of water consistently. Because conditions change daily and throughout the day, it is preferable to turn on the system after checking the plants and determining that they require watering. Proper watering occurs when 10% to 15% of the water applied drains from the bottom of the container. This helps to ensure that the entire root ball is wet. Regardless of whether watering is manual or automatic, it should be done early enough in the day to allow excess moisture to evaporate, especially from the leaves. If plants in a greenhouse environment are watered later in the day, they may remain wet throughout the night, providing optimal conditions for fungal growth. On very hot days and especially with smaller plants, it may be necessary to water more than once each day.

Other Considerations

Bottom heat is beneficial for seed germination and for rooting cuttings. Electric mats that plug into an outlet or a thermostat are easily obtained from greenhouse supply companies. Hot water tubing is also available. Mats that allow for circulation of hot water through a series of built-in channels are a low-cost, convenient way to provide bottom heat. These mats are connected to a hot water heater that can be dedicated to this purpose, if desired.

For all the different systems--heating, cooling, moisture, lighting, and bottom heat--sensors and controls will prove to be quite convenient. Thermostats may be used for heating and cooling, and moisture sensors can be used for turning on mist systems. Timers can be set up for watering.

Other Ways of Creating a Greenhouse Environment

If you do not have the space, time, or money to have your own home greenhouse, but you still want to start seeds early or overwinter plants that are not quite hardy in your region, one alternative that many people find practical is the cold frame. The top lid of the cold frame is glass, polycarbonate sheets, plastic film, or other glazing material that is oriented at an angle to face the sun in spring, when the cold frame will be used. The sides can be easily constructed of lumber or another material. Foam insulation board can be useful for lining the inside walls and helping to contain the warmth that enters through the glazing on top. Alternatively, hay bales can be used to form the walls. Hay or straw may also be placed inside the cold frame to provide insulation to the containers the plants are in. Manure and compost, as they decompose, generate a lot of heat. It is possible to harness this heat inside a cold frame to provide the necessary bottom heat for starting seeds or rooting cuttings. Something as simple as an old window placed on top of hay bales that have been arranged to form a square or rectangle, can provide an inexpensive and practical cold frame.

PLACING PLANTS OUTDOORS AND BRINGING THEM BACK IN

The types of plants that people place outside in summer but must bring indoors for the winter include tropical foliage plants, orchids, and other tender flowering plants. One should be aware of certain factors when bringing plants indoors after they have been outdoors for several months. One crucial factor is light intensity. Outdoors in summer, plants receive high light intensity. Even plants that have been placed in a shady location may receive more light outside than they will when they are moved indoors. Thus, many plants will stop growing or will grow much more slowly after being moved inside. If the plant is a high light-requiring plant, it is best to provide the highest amount of light available indoors. This may mean placing the plants in a sunny window or providing supplemental lighting. If the plants have a dormant season, during which they should not be watered, this is a good time to begin reducing the amount of water applied each week.

Plants that have been outside may have insect infestations. Be sure to check thoroughly for mites, aphids, snails, and other pests before bringing the plants indoors. Spray plants with a mild soap solution to clean them and remove any pests. If you actually see pests or signs of pest damage, treat the plants with a pesticide before bringing them indoors.

When plants are outside, they are subjected to fluctuating day and night temperatures, whereas the temperatures in a home fluctuate much less. It is not necessarily desirable to provide widely fluctuating temperatures for plants. The best practice for growing plants indoors is to learn the optimal conditions for a particular plant and provide the conditions as closely as one is able. After having been outside, many plants have developed a lot of good growth and have been able to store excess carbohydrates that will help them get through the less than optimal conditions indoors during the winter months. Temperatures indoors that fluctuate less can be a helpful factor for plants because the relatively cooler day temperatures will benefit photosynthesis as well as allowing stomates to remain open, and respiration will be slower at the cooler night temperatures. In summary, the winter months are more or less a resting time when plants will maintain the status quo or perhaps use some of their reserve carbohydrates but will not grow.

REPOTTING A HOUSEPLANT

When a plant has outgrown its container, there are several signs. First, it becomes increasingly difficult to keep it well watered. Because the roots fill the pot and may be encircling it, they quickly absorb any water provided. Second, because the plant is probably drying out often and staying dry too long, the leaves begin to turn brown or leaf margins turn brown because they are necrotic. Finally, roots may be seen emerging from drainage holes in the bottom of the pot.

When you attempt to remove the plant from the pot, a root-bound plant will come out with its entire root ball intact. If the roots have begun encircling the pot, it is very important to prune them or slice through the outer ring of roots to stop this habit. Otherwise, after repotting the new plant, the roots will still follow their circular habit and will girdle the plant or stunt its growth. If the roots are not too tightly bound, it is not necessary to disturb them, but simply place the entire root ball into the next size container. If the roots have grown to a tight mass, then gently tease them out with your fingers, massaging them free from the mass so that they will grow in a downward direction once they are in the new container.

When repotting plants, it is common to place them in the next size container rather than jump to a much larger pot. Another possibility with plants that can be divided is to divide the plant and grow each new plant in the same size of container as the original. As is usual for container-grown plants, be sure the containers you use have one or more drainage holes. Do not add rocks or gravel to the bottom of the pot, unless you wish to create a shallower root environment than the container provides.

To plant in the new container, place some potting soil into the center of the pot. Set the new plant into place, and fill in around the edges with potting soil. Allow room for about 1 inch at the top of the pot for watering. This will prevent soil spillage during successive watering. Set the pot on a tray to catch excess water. Place the plant in the desired location.

SUMMARY

Indoor plants can be easy or challenging to grow. Many have adapted to a shady environment with little temperature fluctuation, so they are well-suited to indoor culture. However, flowering plants and other more demanding plants can also be grown indoors. It is necessary to understand where plants originated to provide an optimal environment and to be successful in growing them indoors. Indoor plants provide benefits beyond aesthetics; in addition to generating oxygen, some of them remove common indoor pollutants from the air.

Lighting is a crucial factor in providing the proper environment for indoor plants. Some of them only require a low level of lighting and may not do well with direct sunlight; others require some direct sunlight during the day. Humidity can affect indoor plants. Humidity inside a home is usually low because of heating and cooling systems.

Plant containers must provide drainage, and they should be appropriately sized. Shallow containers tend to stay moist longer than deeper ones. Small plants should be grown in small containers, and large ones should not be allowed to become root-bound. A well-draining medium is desirable for most container-grown plants. Overwatering and underwatering are the two main reasons for death of indoor plants, and this is often directly related to container size and media type.

Fertilizer is usually provided at a low level, unless a lot of growth is desired, and the proper environmental conditions can be provided to support it. Greenhouses provide a space in which to grow plants while maintaining better control over environmental factors such as light, humidity, and temperature. They can be quite expensive, but provide the serious hobbyist a rewarding place to pursue their horticultural interests.

HANDS-ON ACTIVITIES

* Force bulbs and grow them indoors.

* Grow a plant in the classroom. Select a plant on the basis of available lighting in the room. i.e., fluorescent lights, windows, and so on. Also take into consideration the high and low temperatures. Is it humid in your room or dry?

* Grow a plant at home or in your dormitory room. Select the plant on the basis of the available light level and space. How can you provide adequate nutrition and water to the plant?

* Write a research paper comparing the differing requirements for three different types of plants that can be grown indoors. Select from cactus, succulent, fern, foliage plant, or indoor flowering plant. Include information on temperatures, humidity, soil/soilless media, fertilizer recommendations, level of watering, and light requirements.

REVIEW QUESTIONS

1. Some houseplants can remove these indoor air pollutants:--, --, and --.

2. Compare the amount of light available indoors depending on the orientation of windows: north, south, east, and west.

3. What is forcing of bulbs and how does it work?

4. Discuss ways to increase moisture retention in soilless media.

5. Discuss ways to improve drainage in soilless media.

6. What is a sign of overwatering?

7. Describe the correct method of watering houseplants.

8. Discuss the effect of soil from outdoors in container-grown plants.

9. Discuss the advantages of fertilizing houseplants above a minimal amount.

10. What is glazing on greenhouses?

SELECTED REFERENCES

Bonsai Clubs International. (n.d.) What is Bonsai? Retrieved July 19, 2005, from http://www.bonsai-bci.com/whatis. html.

Clarke, G. (1997). Indoor plants. Pleasantville, NY: Reader's Digest.

De Hertogh, A. A. (1977). Holland bulb forcer's guide (2nd ed.). New York: Netherlands Flower-Bulb Institute.

Lancaster, R., & Biggs, M. (1998). What houseplant where. New York: Dorling-Kindersley.

Prescod, A.W. (1992). More indoor plants as air purifiers. Pappus, 11, 4.

Whiteside, K. (1999). Forcing, etc. the indoor gardener's guide to bringing bulbs, branches and houseplants into bloom. New York: Workman.

Gus De Hertogh: Pioneer of Bulb Forcing

The practice of forcing bulbs to obtain flowering at a specified time is a relatively modern phenomenon, with thanks mainly to Dr. Gus De Hertogh. Dr. De Hertogh was a researcher in Michigan at a time when the Holland bulb industry needed help in learning how to market their product to the United States. The main problem was forcing the bulbs under American conditions. Through his research, he devised protocols for shipping bulbs, handling them after they arrived from Europe, cooling them, and then forcing them for greenhouse production. His results were a great boon for the bulb industry and led to the publication of the information in the Holland Bulb Forcer's Guide, the authority on bulb production and forcing. Dr. De Hertogh has received many awards and commendations for his research. The rest of us have been rewarded with the beauty of all the tulips, narcissus, hyacinths, and other bulbs that we can now force at home ourselves. They are also available in florist shops when the winter cold seems never ending, bringing special and much appreciated liveliness and color into our homes.

Bonsai

The technique of bonsai originated in Asia as a means of imitating plants in nature that have usually grown in adverse conditions that resulted in the plant's growth being stunted and misshapen. Bonsai means tree-in-a-pot in both Japanese and Chinese. The technique involves a great deal of shoot and root pruning, coupled with growing the plants in root-restricted environments. Most often woody plants are used in bonsai. Wiring is used to give the plants artistic, unusual shapes so that they appear gnarled or weeping or to give branches specific shapes.

Some of the classical shapes for bonsai include informal upright, formal upright, broom, slanting, windswept, cascade, twin trunk, multiple trunk, raft and group, clasped to rock, and literati (bunjin) form. Each form has specific rules about trunk shape and size, branch angle, and even root characteristics (Fig. 12-8). Special pruning tools are used to achieve desired shapes and to direct growth. Pruning is not constant but occurs at specific times of year during the growing cycle.

Bonsai plants can be started from seed, from cuttings, and from plants purchased at nurseries or transplanted from the wild. They can also be purchased in a bonsai form already.

The beginning student of bonsai should seek professional guidance and detailed information, as it is necessary to fully understand and appreciate the special needs required by bonsai plants before one can achieve success. Table 12-5 lists some plants that are successfully used as bonsai. The following are some tips and guidelines for growing and caring for bonsai plants.

Bonsai trees are normally grown outdoors, and they may be deciduous or evergreen. Both temperate and tropical plants are used. For tropical plants, it is necessary to bring them indoors during cold weather to protect them from freezing. However, bonsai plants do not otherwise survive well indoors for several reasons. One is that indoor lighting is inadequate for plant growth. Remember that most houseplants have evolved in areas of low light, such as the understory in rainforest areas. Other plants that can be grown indoors require supplemental lighting for normal growth and flowering. Another reason many bonsai trees do not do well as indoor plants is because of their requirements for cool temperatures and the shortening photoperiod in fall that signal dormancy, followed by chilling in winter that is required by the flowering buds of many of these plants.

For tropical bonsai species that will be grown indoors for most of the year, several conditions should be met to maintain optimal growth. One of these is adequate lighting. This includes both high light levels and light of the proper wavelength (see chapter 7 for a discussion of this topic). High-intensity discharge and fluorescent lamps can provide these. Light requirements may be met by a sunny window, but whether light will be adequate depends on the number of hours of sunlight provided as well as the intensity of the light. However, on cloudy, short days light is usually inadequate.

Another adverse condition found with indoor climate control systems is low humidity. Both air conditioning in summer and heating in winter dry the air inside a home to as low as 20% to 30% humidity. Avoid placing plants in drafty locations where moisture will be moved away from the leaves, causing the plant to dry out too fast. Use a pebble tray to keep some water around the vicinity of the plant (see Fig. 12-5). Also, a humidifier can increase the humidity around the vicinity of the plant.

Bonsai plants are trained to grow in small spaces, with restricted root balls. The small, shallow containers commonly used for bonsai tend to be poorly draining. Because plants require moisture and oxygen in the root environment, it is necessary to remedy the drainage situation so that both are available to the plant most of the time. The remedy for poor drainage due to shallow depth is to include gravel, sharp sand or perlite in the root media to increase drainage. Good, rapid drainage then leads to the need to water bonsai plants regularly to ensure adequate moisture availability. Bonsai plants should be checked at least once a day and watered as needed, allowing the roots to dry slightly between watering, but never allowing the root ball to become completely dry. The top one-half inch or so of the medium should be dry before the plant is watered. The length of time required for this to occur will vary depending on temperature, air movement, humidity, and growth of the plant.

[FIGURE 12-8 OMITTED]

In general, the best time of day to water bonsai is in the morning. Watering in the morning ensures that plants have the water they require during the heat of the day and during the main growth period of the day. It also allows plants to dry adequately before night and reduces the incidence of fungal growth that often occurs under cool, moist conditions. Provide enough water so that excess drains from the bottom of the pot. This helps to ensure that the entire root ball has been wetted.

Dr. Marietta Loehrlein currently teaches horticulture classes at Western Illinois University in Macomb, Illinois. She earned both her bachelor's degree in Agronomy and her master's degree in Plant Genetics at The University of Arizona. Her master's research project was concerned with germination problems associated with triploid seeds, from which seedless watermelons grow. Following that she worked for 5 years in a breeding and research program for Sunworld, International near Bakersfield, California. She worked with peaches, nectarines, plums, apricots, and cherries. Then she returned to school to earn her Ph.D. in Horticultural Genetics at The Pennsylvania State University. Her Ph.D. research focused on flowering processes in regal pelargonium (also called Martha Washington geraniums). While at The Pennsylvania State University, she bred a new cultivar of regal pelargonium, "Camelot." At Western Illinois University, Dr. Loehrlein teaches nine courses: Greenhouse and Nursery Management, Introductory Horticulture, Landscape Design, Landscape Management, Home Horticulture, Plant Propagation, Turf Management, and two courses in Plant Identification.
TABLE 12-1

COMMON NAME               GENUS/SPECIES           TEMPERATURE

Foliage

Aluminum plant            Pilea cadieri           75-85

Arrowhead plant           Syngonium               75-85

Asparagus fern            Asparagus               75-85

Baby tears                Helxine                 45-65

Begonia                   Begonia                 75-85

Bromeliad                 Aechmea                 60-75

Bromeliad                 Guzmania                60-75

Bromeliad                 Neoregelia              70-80

Bromeliad                 Nidularium              65-75

Cabbage palm              Cordyline               60-85

Caladium                  Caladium                70-75

Calathea                  Calathea                60-64

Cast-iron plant           Aspidistra elatior      75-85

Chinese evergreen         Aglaonema               75-85

Cleyera                   Cleyera                 55-70

Coffee                    Coffea arabica          60-70

Coleus                    Coleus                  75-90

Croton                    Codiaeum                65-85

Date palm                 Phoenix spp.            65-70

Dracaena                  Dracaena                60-85

Dumb cane                 Dieffenbachia           58-64

English ivy               Hedera                  65-78

European fan palm         Chamaerops              50-75

False aralia              Dizygotheca             60-75

False castor oil plant    Fatsia                  50-70

Fig                       Ficus                   55-60

Fittonia                  Fittonia                65-75

Golden pothos,            Epipremnum aureum       60-80
  devil's ivy

Howe's palm               Howeia                  55-65

Japanese laurel           Aucuba japonica         75-85

Maranta                   Maranta                 60-70

Norfolk Island pine       Araucaria               40-50

Palm                      Chamaedorea             57-70

Peperomia                 Peperomia               64-68

Philodendron              Philodendron            58-64

Purple velvet leaf        Gynura                  75-85

Screw pine                Pandanus                68-72

Spider plant, airplane    Chlorophyllum           50-75
  plant                   comosum

Spiderwort                Tradescantia            50-60

Swiss cheese plant        Monstera                58-65

Umbrella plant            Cyperus                 55-68

Umbrella plant            Schefflera              65-80

Wandering Jew             Tradescantia zebrina    60-70

Yucca                     Yucca                   45-65

Zebra plant               Aphelandra              75-85

Ferns

Bird's nest fern          Asplenium nidus         65-75

Boston fern               Nephrolepis exaltata    60-75

Boston fern               Nephrolepis exaltata    60-75
                            'Bostoniensis'

Brake fern                Pteris spp.             55-65

Button fern               Pellaea rotundifolia    60-75

Climbing bird's nest      Polypodium punctatum    60-75
  fern

Creeping moss             Selaginella             55-60

Deer's foot fern          Davallia canariensis    60-75

Hart's tongue fern        Phyllitis               60-75
                            scolopendrium

Holly fern                Cyrtomium falcatum      50-75

Holly fern                Poloystichum tsus-      55-65
                            simense

Maidenhair fern           Adiantum raddianum      65-75

Maidenhair fern           Adiantum tenerum        65-75

Palm-leaf fern            Blechnum capense        60-64

Rabbit's foot fern        Polypodium aureum       55-60

Stag's horn fern          Platycerium             60-75
                            bifurcatum

Tree maidenhair           Didymochlaena           60-75
                            truncatula

Flowering Plants

Achimenes                 Achimenes               55-60

African violet            Saintapaulia ionantha   65-75

Azalea                    Rhododendron indicum    50-60

Basket vine               Aeschynanthus           65-70

Billbergia                Billbergia spp.         70-80

Bird of paradise          Strelitzia reginae      60-85

Bottlebrush               Callistemon citrinus,   45-65
                            Callistemon
                            speciosus

Bougainvillea             Bougainvillea           50-80

Bouvardia                 Bouvardia x domestica   55-60

Brassia                   Brassia                 65-70

Bromeliad                 Tillandsia cyanea       75-85

Bromeliad                 Vriesia splendens       65-70

Browallia                 Browallia               65-75

Brunsfelsia               Brunsfelsia             55-60

Calla lily                Zantedeschia            50-65
                            elliottiana

Camellia                  Camellia japonica,      50
                            Camellia sinensis

Cape primrose             Streptocarpus x         65-70
                            hybridus

Chenille plant            Acalypha                60-65

Cineraria                 Cineraria grandiflora   60-70

Coleus                    Coleus fredericii,      75
                            Coleus thyrsoideus

Crossandra                Crossandra              64
                            infindibuliformis

Cyclamen                  Cyclamen persicum       46-50

Cymbidium orchid          Cymbidium spp.          45-54

Dendrobium orchid         Dendrobium spp.         75 during
                                                  growth,
                                                  46-50
                                                  during
                                                  dormancy

Egyptian star cluster     Pentas                  60-75

Fibrous rooted begonia    Begonia semperflorens   65-70

Flame plant               Anthurium scherze-      64-68
                            ranum, Anthurium
                            andreanum

Florist's hydrangea       Hydrangea macrophylla   40-46

Flowering maple           Abutilon                57-63

Fuchsia                   Fuchsia hybrids         55-75

Gardenia                  Gardenia augusta        60-64

Glorybower                Clerodendron spp.       55-75

Glory lily                Gloriosa                60-66

Gloxinia                  Sinningia regina,       60-70
                            Sinningia speciosa,
                            Sinningia hybrids

Hoya                      Hoya carnosa, Hoya      50-54
                            bella

Impatiens, touch-me-      Impatiens balsamina     68
  not, 'Busy Lizzie'

Ivy geranium              Pelargonium peltatum    60-75

Jasmine                   Jasminium               55-75

Kaffir lily               Clivia miniata          55-60

Lollipop plant            Pachystachys lutea      59

Miniature rose            Rosa chinensis var.     50-85
                            indica

Mum                       Dendranthema            60-70
                            grandiflorum

Odontoglossum             Odontoglossum           50-60

Oncidium orchid           Oncidium                Varies by
                                                    species

Ornamental chili          Capsicum                60-70
  pepper

Pansy orchid              Miltonia spp.           50-60

Passion flower            Passiflora spp.         45-65

Peace lily                Spathiphyllum           60-75

Periwinkle                Catharanthus roseus     70-80

Persian violet            Exacum affine           55-70

Pocketbook plant          Calceolaria             50-54

Poinsettia                Euphorbia pulcherrima   64-68

Pomegranate               Punica granatum         45-75

Regal geranium            Pelargonium             50-75
                            domesticum

Rose mallow               Hibiscus rosa-          54-59
                            sinensis

Shrimp plant              Drejerella              54-59

Slipper orchid            Paphiopedilum           54-59

Tuberous rooted           Begonia x               75-85
  begonia                   tuberhynrida

Wood sorrel,              Oxalis rubra            54-57
  shamrock

Zonal geranium,           Pelargonium x           75-85
  garden geranium           hybridum

Cacti and Succulents

                          Parodia                 45-75

Aloe                      Aloe vera, Aloe         40-70
                            variegata

Barrel cactus             Echinocereus spp.       65-85

Bishop's cap cactus       Astrophytum ornatum     40-70

Christmas cactus          Schlumbergera           55-65
                            bridgessii

Easter cactus             Rhipsalidopsis          54-80

Euphorbia                 Euphorbia               65-85
                            pseudocactus

Gasteria                  Gasteria liliputana     50-54

Gymnocalycium             Gymnocalycium spp.      70-85

Haworthia                 Haworthia spp.          50-54

Hens and chicks,          Sempervivum             35-47
  houseleek

Jade plant                Crassula argentea       50-60
                            (Crassula
                            portulaca, Crassula
                            arborescens)

Kalanchoe                 Kalanchoe spp.          50-75

Living stones             Lithops                 40-70

Mesems, living stones     Argyroderma             40-70

Moonstones                Pachyphytum oviferum    45-65

Neoporteria               Neoporteria             45-75
                            (Eriosyce) spp.

Old man cactus            Cephalocereus senilis   59-75

Painted lady              Echeveria derenbergii   45-65

Peanut cactus             Chamaecereus            28-65
                            sylvestri

Pincushion cactus         Mammillaria spp.        45-75

Prickly pear              Opuntia                 45-95

Queen Victoria            Agave victoria-         40-70
  century plant             reginae

Snake plant, mother-      Sanseveria              59-80
  in-law's tongue           trifasciata

Stonecrop                 Sedum spp.              46-75

Thanksgiving cactus,      Schlumbergera           54-80
  false Christmas           truncata
  cactus

COMMON NAME               LIGHT                   MOISTURE

Aluminum plant            Medium low              Moist

Arrowhead plant           Bright, indirect        Moderate, humid

Asparagus fern            Medium                  Moderate

Baby tears                Indirect                Moderate

Begonia                   Outside in summer       Medium to moist

Bromeliad                 Indirect                Moist

Bromeliad                 Bright, indirect;       Moist
                            outside in summer

Bromeliad                 Bright, indirect        Moist

Bromeliad                 Partial shade           Moist

Cabbage palm              Bright, indirect        Moist

Caladium                  Bright indirect         Moist

Calathea                  Bright indirect         Moist, humid

Cast-iron plant           Low                     Medium

Chinese evergreen         Indirect, north         Medium
                            window

Cleyera                   Semishady               Moist

Coffee                    Semishady               Moderate

Coleus                    Bright indirect         Moist

Croton                    Bright indirect         Moist

Date palm                 Outside in summer       Moist

Dracaena                  Bright, indirect        Moist

Dumb cane                 Bright, indirect        Moist
                            light

English ivy               Bright, indirect;       Moderate
                            outside shade in
                            summer

European fan palm         Bright                  Moderate

False aralia              Bright, indirect        Moderate

False castor oil plant    North window or         Moist
                            shade

Fig                       Bright, indirect        Moist

Fittonia                  Bright, indirect        Moist, humid

Golden pothos,            Full to partial shade   Moderate
  devil's ivy

Howe's palm               Shady                   Moderate dry

Japanese laurel           Low                     Medium

Maranta                   Bright, indirect        Moderate

Norfolk Island pine       Shade                   Moderate to light

Palm                      Bright indirect         Moderate

Peperomia                 Bright, indirect        Dry, humid

Philodendron              Bright, indirect        Moist

Purple velvet leaf        Sunny                   Moderate

Screw pine                Bright, indirect        Moist

Spider plant, airplane    Low to high             Low to moderate
  plant

Spiderwort                Indirect                Moderate

Swiss cheese plant        Indirect; outside       Moist
                            shade in summer

Umbrella plant            Well-lit                Wet

Umbrella plant            Sun                     Moderate

Wandering Jew             Bright                  Moderate

Yucca                     Sunny; outside in       Moderate dry
                            summer

Zebra plant               Good, indirect          Moist

Ferns

Bird's nest fern          Shady                   Humid; moderate;
                                                    dry in winter

Boston fern               Indirect sunlight       Humid; moderate;
                                                    dry in winter

Boston fern               Indirect sunlight       Humid; moderate;
                                                    dry in winter

Brake fern                Shady                   Humid, moist

Button fern               Good light              Humid; moderate;
                                                    drier in winter

Climbing bird's nest      Shady                   Humid; moderate
  fern

Creeping moss             Shady                   Moist

Deer's foot fern          Shady                   Humid; moderate;
                                                    dry in winter

Hart's tongue fern        Shady                   Humid; moderate;
                                                    dry in winter

Holly fern                Shady                   Humid; moderate;
                                                    dry in winter

Holly fern                Shady                   Humid, moist

Maidenhair fern           Shady                   Humid; moderate;
                                                    dry in winter

Maidenhair fern           Shady                   Humid; moderate;
                                                    dry in winter

Palm-leaf fern            Shady                   Humid; moderate;
                                                    dry in winter

Rabbit's foot fern        Shady                   Humid; moderate;
                                                    drier in winter

Stag's horn fern          Bright, indirect        Humid; moderate;
                            sunlight                drier in winter;
                                                    use tepid water

Tree maidenhair           Shady                   Humid; moderate;
                                                    dry in winter

Flowering Plants

Achimenes                 Bright, indirect        Humid, moist

African violet            Bright, indirect        Moderate: water
                                                    from below with
                                                    tepid water

Azalea                    Indirect, partial       Moderate, humid
                            shade

Basket vine               Partial shade           Humid, moderate
                                                  moisture

Billbergia                Bright, indirect        Humid; moderate;
                                                    drier in winter

Bird of paradise          Bright, indirect;       Moderate
                            outside in summer

Bottlebrush               Bright light            Moderate

Bougainvillea             Outside in summer;      Moderate; drier in
                            bright light in         winter
                            winter

Bouvardia                 Bright, indirect        Moderate; drier in
                                                    winter

Brassia                   Bright, indirect        Humid; moderate
                                                    moisture

Bromeliad                 Bright                  Humid, moist

Bromeliad                 Bright, indirect        Humid, moist;
                                                    lukewarm water

Browallia                 Good                    Moist

Brunsfelsia               Half-shady; more        Humid; moderate;
                            light in winter         drier in winter

Calla lily                Bright; outside in      Moist; dry in
                            summer                  dormancy (after
                                                    flowering)

Camellia                  Semi-shady; outdoors    Moderate; less in
                            in summer               summer; use
                                                    lukewarm water

Cape primrose             Bright, indirect        Moderate; tepid
                                                    water

Chenille plant            Bright, indirect        Moderate

Cineraria                 Shade or indirect       Moist
                            light; outside in
                            summer

Coleus                    Bright, indirect        Moist, drier in
                                                    summer

Crossandra                Good, indirect light    Humid; moist during
                                                    growing season,
                                                    moderately after
                                                    flowering; use
                                                    lukewarm water

Cyclamen                  Bright, indirect        Moist during
                                                    growing season,
                                                    dry while dormant

Cymbidium orchid          High, indirect light    Moist in summer,
                                                    but allow to dry
                                                    between waterings;
                                                    drier in winter

Dendrobium orchid         Bright, indirect        Humid and moist
                            sunlight                while growing,
                                                    drier during
                                                    dormancy

Egyptian star cluster     Bright, indirect        Moderate; water
                                                    sparingly after
                                                    blooming

Fibrous rooted begonia    Bright, indirect        Humid, moderate

Flame plant               Shady                   Humid

Florist's hydrangea       Shady; outside in       Moist
                            summer in a shady
                            location

Flowering maple           Bright, indirect;       Moderate
                            outside in summer

Fuchsia                   Bright; outside in      Humid; moist; drier
                            summer                  in winter

Gardenia                  Bright                  Humid; moderate
                                                    watering; use
                                                    tepid water

Glorybower                Indirect sunlight       Humid, moist, drier
                                                    in winter

Glory lily                Bright, indirect        Moderate

Gloxinia                  Bright, indirect        Moist, lukewarm
                                                    water; do not
                                                    spray leaves

Hoya                      Bright, indirect        Moderate, less in
                                                    winter

Impatiens, touch-me-      Bright, indirect;       Moist
  not, 'Busy Lizzie'        outside in summer
                            in a shady location

Ivy geranium              Bright, direct;         Moderate
                            outside in summer

Jasmine                   Bright, indirect        Moist; drier in
                                                    winter

Kaffir lily               Bright, indirect        Moist but allow to
                                                    dry between
                                                    waterings; drier
                                                    in winter

Lollipop plant            Bright, indirect        Moist, keep drier in
                                                    winter; use tepid
                                                    water

Miniature rose            Sunny; outside in       Moderate dry
                            summer

Mum                       Outside in summer       Moist
                            and fall; indirect
                            light in winter

Odontoglossum             Shady                   Moist

Oncidium orchid           Bright, indirect        Humid; water
                                                    sparingly

Ornamental chili          Outside in summer;      Moderate
  pepper                    bright, indirect
                            light in winter

Pansy orchid              Shady                   Moist

Passion flower            Good, direct            Moist; drier in
                            sunlight; outside       summer
                            in summer

Peace lily                Shady                   Moderate

Periwinkle                Outside in summer;      Moist; drier in
                            bright, indirect        winter
                            light in winter

Persian violet            Bright, indirect        Moist

Pocketbook plant          Indirect light          Moist

Poinsettia                Good, indirect light;   Moist, but allow to
                            outside in summer       dry between
                                                    waterings; use
                                                    tepid water

Pomegranate               Sunny; outside in       Moderate
                            summer

Regal geranium            Bright, direct;         Moderate
                            outside in summer

Rose mallow               Bright, indirect;       Moist
                            outside in summer

Shrimp plant              High light; outside     Moist in summer,
                            in summer               less in winter

Slipper orchid            Good                    Moist; drier in
                                                    winter

Tuberous rooted           Bright, indirect        Moderate
  begonia

Wood sorrel,              Sunny                   Water sparingly
  shamrock

Zonal geranium,           Bright, direct;         Moderate
  garden geranium           outside in summer

Cacti and Succulents

                          Bright light            Moist in summer, but
                                                  allow to dry between
                                                  waterings, dry in
                                                  winter

Aloe                      Bright                  Moist; dry in winter

Barrel cactus             Bright; outside in      Dry between watering
                            summer

Bishop's cap cactus       Bright                  Dry in summer, not
                                                    at all from fall
                                                    to spring

Christmas cactus          Semi-shade in           Moist in summer and
                            summer, bright          autumn, drier in
                            light in winter         winter and spring

Easter cactus             Semishade in summer,    Moist in summer and
                            bright light in         autumn, drier in
                            winter                  winter and spring

Euphorbia                 Bright                  Moderate to dry

Gasteria                  Bright, indirect        Moist in spring and
                                                    summer, dry in
                                                    winter

Gymnocalycium             Partial shade           Dry between
                                                    watering, dry in
                                                    winter

Haworthia                 Bright, indirect        Moist in spring and
                                                    summer, dry in
                                                    winter

Hens and chicks,          Bright light            Moderate; dry in
  houseleek                                         winter

Jade plant                Bright, indirect        Allow to dry between
                                                    watering

Kalanchoe                 Bright, indirect        Dry air; water
                                                    thoroughly in
                                                    summer, keep
                                                    fairly dry in
                                                    winter

Living stones             Bright                  Moist; dry in winter

Mesems, living stones     Bright                  Moist; dry in winter

Moonstones                Bright                  Moist in summer, dry
                                                    in winter

Neoporteria               Bright light            Moist in summer, but
                                                    allow to dry
                                                    between waterings,
                                                    dry in winter

Old man cactus            Good light              Light watering in
                                                    summer, dry in
                                                    winter

Painted lady              Bright                  Moist in summer, dry
                                                    in winter

Peanut cactus             Moderate                Regular watering in
                                                    summer, dry in
                                                    winter

Pincushion cactus         Bright light            Moist in summer, but
                                                    allow to dry
                                                    between waterings,
                                                    dry in winter

Prickly pear              Bright light;           Moderate in summer,
                            outdoors in summer      dry in winter

Queen Victoria            Bright                  Moist; dry in winter
  century plant

Snake plant, mother-      Dim to bright           Moderate in summer,
  in-law's tongue                                   drier in winter

Stonecrop                 Bright light            Moderate; dry in
                                                    winter

Thanksgiving cactus,      Semi-shade in           Moist in summer and
  false Christmas           summer, bright          autumn, drier in
  cactus                    light in winter         winter and spring

TABLE 12-2
Plants and the Pollutants They Remove

COMMON NAME          GENUS/SPECIES            POLLUTANT

Aloe                 Aloe vera                Formaldehyde

Arrowhead plant      Syngonium podophyllum    Good for formaldehyde

Azalea               Rhododendron indicum     Good for formaldehyde

Bamboo palm          Chamaedorea seifrizii    Excellent for benzene
                                                and formaldehyde,
                                                good for carbon
                                                monoxide

Banana               Musa oriana              Excellent for
                                                formaldehyde

Bromeliad            Guzmania 'Cherry'        Excellent for
                                                formaldehyde and
                                                xylene

Bromeliad            Neoregelia carolinae     Good for xylene
                       'Perfecta Tricolor'

Chinese evergreen    Aglaonema modestum       Formaldehyde, benzene,
                                                toluene, carbon
                                                monoxide

Christmas cactus     Schlumbergera x          Formaldehyde
                       buckleyi

Dendrobium orchid    Dendrobium spp.          Acetone, ammonia,
                                                chloroform, ethyl
                                                acetate, methyl
                                                alcohol, formaldehyde
                                                and xylene

Dumbcane             Dieffenbachia            Good for formaldehyde
                       maculata

Elephant ear         Philodendron             Excellent for
philodendron           domesticum               formaldehyde

English ivy          Hedera helix             Excellent for benzene,
                                                good for formaldehyde,
                                                trichloroethylene,
                                                carbon monoxide

Gerbera daisy        Gerbera jamesonii        Excellent for benzene
                                                and trichloroethylene,
                                                good for formaldehyde,
                                                carbon monoxide

Golden pothos        Epipremnum aureum        Excellent for carbon
                                                monoxide and benzene,
                                                good for formaldehyde

Heart leaf           Philodendron             Excellent for
philodendron           oxycardium               formaldehyde

Janet Craig          Dracaena deremensis      Excellent for benzene
  dracaena             'Janet Craig'            and trichloroethylene

Lacy tree            Philodendron selloum     Excellent for
  philodenron                                   formaldehyde

Madagascar dragon    Dracaena marginata       Excellent for benzene,
  tree                                          good for formaldehyde
                                                and trichloroethylene

Mass cane            Dracaena fragrams        Excellent for
                       'Massangeana'            formaldehyde

Miniature umbrella   Schefflera arboricola    Good for benzene,
  plant                                         formaldehyde and
                                                toluene

Mother-in-law's      Sansevieria trifas-      Excellent for benzene
  tongue, snake        ciata 'Laurentii'        and formaldehyde,
  plant                                         good for
                                                trichloroethylene

Oyster plant         Tradescantia             Good for formaldehyde
                       sillamontana

Peace lily           Spathiphyllum 'Mauna     Excellent for benzene
                       Loa'                     and trichloroethylene,
                                                good for formaldehyde,
                                                carbon monoxide

Peperomia            Peperomia obtusifolia    Good for formaldehyde

Phalaenopsis         Phalaenopsis spp.        Excellent for
  orchid                                        formaldehyde and
                                                xylene

Poinsettia           Euphorbia pulcherrima    Excellent for
                                                formaldehyde

Pot mum              Chrysanthemum            Excellent for trichlo-
                       morifolium               roethylene, good for
                                                benzene, formaldehyde,
                                                and carbon monoxide

Spider plant         Chlorophytum elatum      Excellent for carbon
                                                monoxide and
                                                formaldehyde

Variegated lily-     Liriope muscari          Excellent for
  turf                 'Variegata'              formaldehyde

Warneckii dracaena   Dracaena deremensis      Excellent for benzene
                       'Warneckii'              and trichloroethylene,
                                                good for formaldehyde

Weeping fig          Ficus benjamina          Good for formaldehyde

TABLE 12-3
Plants and Their Optimal Light Levels

COMMON NAME                                                LIGHT LEVEL

Flowering maple, chenille plant, lipstick vine, agave,     High
  bamboo, wax begonia, cacti, cattleya orchid, citrus,
  coleus, 'Tricolor' dracaena, fatshedera, poinsettia,
  purple velvet plant, variegated ivy, geranium,
  amaryllis, shrimp plant, kalanchoe, oxalis

Maidenhair fern, anthurium, begonia, spider plant,         Medium
  fishtail palm, ti plant, dumbcane, weeping fig,
  fiddleleaf fig, peperomia, Boston fern, staghorn fern,
  Swedish ivy, baby tears, wandering Jew, ginger

Chinese evergreen, Norfolk Island pine, asparagus fern,    Low
  cast iron plant, parlor palm, devil's ivy, rubber
  plant, fittonia, philodendron, peace lily, snake
  plant, arrowhead, bromeliads

TABLE 12-4
Specific Requirements for Forcing Bulbs Indoors

COMMON NAME       GENUS AND SPECIES        WEEKS OF     WEEKS TO
                                           CHILLING     BLOOM

Amaryllis         Hippeastrum              None         6-8

Crocus            Crocus chrysanthus       15           2-3

Crocus            Crocus vernus            15           2

Daffodil          Narcissus                15-17        2-3

Fritillary        Fritillaria meleagris    15           3

Glory of the      Chionodoxa lucilae       15           2-3
  Snow

Grape             Muscari armeniacum       13-15        2-3
  hyacinth

Grape             Muscari botryoides       14-15        2-3
  hyacinth

Hyacinth          Hyacinthus               11-14        2-3

Iris              Iris danfordiae          15           2-3

Iris              Iris reticulata          15           2-3

Paper whites      Narcissus tazetta        None         3-5

Siberian          Scilla siberica          15           2-3
  squill

Snowdrop          Galanthus nivalis        15           2

Tulip             Tulipa                   14-20        2-3

Winter            Erianthus hyemalis       15           2
  Aconite

Source: The Netherlands Flower Bulb Information Center,
Brooklyn, NY.

TABLE 12-5
Some Woody Plants That Work Well for Bonsai

COMMON NAME                     BOTANICAL NAME

Azalea                          Rhododendron spp.

Black pines                     Pinus thunbergii

Bougainvillea                   Bougainvillea glabra

Chinese juniper                 Juniperus x media

Flowering crab apple            Malus spp.

Fukien tea                      Ehretia buxifolia

Gardenia                        Gardenia jasminoides

Ginkgo                          Gingko biloba

Hokkaido elm                    Ulmus parvifolia 'Hokkaido'

Japanese maple                  Acer palmatum

Japanese Zelkova, Japanese      Zelkova serrata
  Keaki tree

Kurume azaleas                  Rhododendron hybrids (Rhododendron
                                  kaempferi, Rhododendron kiusianum
                                  and Rhododendron obtusum)

Lantana                         Lantana camara

Littleleaf boxwood              Buxus microphylla 'Compacta,' 'Morris
                                  Midget'

Little-leaf Cotoneaster         Cotoneaster microphylla

Norfolk Island pine             Araucaria excelsa

Olive                           Olea europa

Satsuki azaleas                 Rhododendron indicum and
                                  Rhododendron simsii

Serissa, yellow-rim             Serissa foetida

Singleseed hawthorn             Craetagus monogyna

Willow leaf fig, Mexicana fig   Ficus nerifolia (Ficus salicifolia)
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Author:Loehrlein, Marietta M.
Publication:Home Horticulture: Principles and Practices
Date:Jan 1, 2008
Words:10420
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