Chapter 17: ornamental trees, shrubs, and groundcovers.
arboretum arboriculture arborist focal point foundation plant specimen plant
Trees and shrubs add beauty to homes, cities, parks, highways, and schools. They provide natural beauty in the woods and wild areas that we wish to recreate in our immediate environment. Trees provide practical solutions in many situations. Some uses for trees are as follows:
* Windbreaks--reduce winter fuel consumption
* Reduce soil erosion, especially on slopes
* Clean the air and provide oxygen
* Increase property value, either for aesthetic reasons or by cash income for wood products
* Cool the air around them and provide shade
* Protect livestock from winds and sun
* Reduce sound from traffic and other noises
* Provide food and a home or shelter for many species of wildlife
* Provide a living snow fence
* Protect crops from damaging wind, improving crop yields
* Beautify homes, farms, public spaces, and roadsides
To maintain the beauty that woody plants can provide, it is important for us to understand how to select the proper plants for the situation and how to properly care for and maintain them.
Trees and shrubs comprise the two largest groups of woody plants. As a matter of fact, lignin, a component of the cell walls of plants, which is largely responsible for the strength and rigidity of trees and shrubs, is the most abundant organic matter on earth. Many vines (lianas) and groundcovers are also woody, and will be treated in this chapter as well.
Trees and shrubs provide the backbone for the landscape. Whether they are deciduous or evergreen, they provide structure and form throughout the year that many herbaceous plants cannot, particularly in temperate climates. Woody plants are ornamental in their shape, texture, and color and bring seasonal interest in the form of colorful bark, flowers, fruit, leaf color, and branch structure.
TREES: SHADE AND ORNAMENTAL
Some trees may grow as large as 100 feet or taller, whereas others mature at a height of only 5 or 6 feet. Some trees have showy flowers while the flowers on others are hardly noticeable. Larger trees often provide a lot of shade and homeowners appreciate them for this value. Smaller trees are appreciated for their ornamental qualities. Most of the small trees used for ornamental purposes have showy flowers, colorful foliage, an aesthetic framework or structure, or a combination of these. Large trees require large spaces that some homes lack. Such trees work well in public areas, such as parks and college campuses. Small trees complement a more intimate space such a small patio area or a mixed border. When selecting a shrub or tree for an area, be mindful of the space available and consider the mature size of the species before you buy it and plant it. Too often a large tree is planted under power lines or too close to a house or building, only to become a very costly mistake later when it must be removed or an ugly problem when it is pruned to avoid power lines (Figs. 17-1 to 17-4, see pages 425-427).
When used alone for its ornamental qualities, a tree is said to be a specimen plant (Fig. 17-5, see page 427). Trees that have showy flowers, unusual foliage or form will become a focal point (Figs. 17-6 to 17-9, see pages 428-429). For this reason, it is important to use care in selecting trees. Too many unusual trees in a small space can become distracting and chaotic rather than aesthetically pleasing. If you desire a grouping of unusual trees, then compose them as you would a picture, so that they complement rather than compete with each other.
Arborists are people whose job it is to monitor the health of trees and to care for them. Arboreta are places where a collection of trees and shrubs are cultivated for scientific or educational purposes. Arboriculture is the care and management of woody plants.
Trees may be deep-rooted or shallow-rooted and may therefore affect structures around them (Fig. 17-10, see page 430). Feeder roots are nonwoody roots concentrated near the soil surface. They are responsible for much of the oxygen, water, and nutrient uptake. Feeder roots normally die and are replaced on a regular basis. Some trees also have root hairs that are responsible for a great deal of nutrient and water uptake. Others, such as many evergreens, form a symbiotic association with a type of fungus called mychorrhizae that live on and in the feeder roots. Mychorrhizae do not harm the tree but aid in water and nutrient uptake. Rototilling under a tree may eventually kill the tree because of the destruction of important feeder roots, root hairs, and mychorrhizae.
Tree root structures vary greatly, depending on soil conditions and moisture availability as well as species. A thin layer of topsoil with heavy clay subsoil restricts root growth to close to the surface, whereas deeper topsoil permits deeper root penetration. In many trees, the root mass is concentrated in the top 12 to 24 inches of soil, in a circumference that exceeds the branch spread, or dripline, by 2 to 4 times its spread or even further (Fig. 17-11, see page 431). Some trees can develop deep taproots that can access water in the soil for 30 feet or more, given adequate drainage and absence of compaction. Table 17-1 (see page 432) lists trees with deep and shallow root systems. Trees with a strong taproot system will eventually slough off their taproot in maturity, which can occur 10 to 40 years later and develop a tiered root system, with feeder roots closer to the surface and sinker roots that permeate deeper layers in the soil. In restricted root environments, such as those present in many urban settings, tree root growth is more restricted than what occurs in forested or other natural, undisturbed areas. In urban areas, even trees that form tap roots or deep root systems may lack a deep tap root if growth is restricted by compaction, a high water table, or heavy soils. These conditions also result in most of the root system developing only 2 to 3 feet below the surface of the soil.
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Tree roots can become injured if the soil around them is altered or compacted. Digging around a tree's roots and rototilling over them are sure ways to damage them and put the tree's health at risk. Adding soil over the tops of roots reduces oxygen and water availability and will be damaging to roots and trees as well. Professionals trained in the care of trees should be consulted if it is necessary to dig in the root zone of a tree. Special pruning techniques can sometimes compensate for the damage that will be caused by root zone damage. During construction, heavy equipment must be kept off the root system.
Lawn grasses compete with trees for nutrients and moisture, which can result in a droughty condition around tree roots. Grasses and trees have different fertilizer needs. Grasses are shallow-rooted and compete with trees for surface moisture. Finally, turfgrass species require sun for optimal growth. Even shade-loving species of fine fescue require some light and will not thrive in deep shade. For all these reasons, you may find it preferable to use mulch or another nonliving groundcover under trees. Irrigation of turf under trees during drought, especially in heavy soils that do not drain well, can result in a waterlogged root area that may lead to the demise of the tree.
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Shrubs may be utilitarian or ornamental, too. They are used for hedges or barriers, for screening, in mixed borders, as specimen plants, and as foundation plants (Figs. 17-12 to 17-16, see pages 432-433). The term foundation plants originated with the use of shrubs around the foundations of homes when foundations were exposed a foot or so above ground level. The term still persists to refer to plants used around the base of the home. Shrubs may be multistemmed or single stemmed. Some trees can be grown as multistemmed shrubs. Flowering shrubs will generally bloom when the plant is 1 to 3 years old. Table 17-2 (see page 434) lists ornamental shrubs for landscaping.
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Groundcovers are useful in areas where turfgrass is not practical, including sloped and shaded sites. Groundcovers are also useful in borders. Many groundcovers are low-growing shrubs. Some of them have a spreading habit to fill in an area, whereas others will spread slowly or not at all. Some groundcovers will grow as vines if they are provided with a vertical surface, although they may also require some support (Fig. 17-17, see page 436). Table 17-3 (see page 437) lists some groundcovers with ornamental qualities. For more information on vines, see chapter 16.
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SELECTING THE TREE, SHRUB, OR GROUNDCOVER
Several factors must be considered when one is selecting a woody plant for landscape use. Ornamental qualities, seasonal interest, plant habit, and mature height and spread are aesthetic, design considerations. More practical considerations are disease and pest problems, soil and site requirements, cold and heat hardiness, and propensity for dropping fruit, limbs, or other plant parts that may be messy or become a nuisance.
The requirements for optimal conditions for plants include soil conditions, temperatures, and amount of sunlight available in a particular location. To understand the requirements of a particular plant, it is helpful to be aware of the plant's natural habitat. Table 17-4 (see page 438) lists plants for problematic soil conditions.
Right Plant for the Site
The amount of sunlight available on a particular site will determine whether a plant can thrive and grow there. Sunlight plays a crucial role in photosynthetic activity, flowering, and fruit development. Some plants can survive in a shady location but fail to flower or bear fruit. Plants that are not shade tolerant may be weak, small, or lanky. Conversely, shade-loving plants grown in full sun may suffer from leaf sunburn or simply die. Table 17-5 (see page 444) lists plants that tolerate shady growing conditions. Some trees are ornamental and do not grow too large. Such trees are ideal for small areas or patios or for growing under larger trees. A list of these is provided in Table 17-6 (see page 445). Other trees can grow quite large and provide ample shade for a yard or home. Some ornamental shade trees are listed in Table 17-7 (see page 447).
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BUYING A TREE OR SHRUB: WHAT TO LOOK FOR
When purchasing a tree, check for defects in tree structure. Some major defects to avoid are double leaders, broken leaders, girdling, or any kind of damage on the trunk or main stem. Look for damaged branches and signs of disease. The latter may be difficult to detect if you are purchasing a tree during the dormant season. Avoid root-bound plants. Purchase plants from a reputable nursery whenever possible or be prepared for inferior quality. Many nurseries have a replacement policy, so check before purchasing.
Improved cultivars are often more expensive to purchase than unimproved plants of the same species. But the extra cost is usually worth it. If you are purchasing a tree that is prone to pests and diseases, such as crabapples, research the cultivars that are disease and pest resistant. Talk to your local nursery professionals for guidance in selecting superior plants. Sometimes local nurseries do not carry the cultivar you want. Then, if possible, locate a reputable mail-order source to obtain such plants. If you purchase plants from other regions, be sure they are going to be hardy in your area. It is preferable to buy plants that have been naturally selected for hardiness in your zone or a colder zone. You should never purchase a plant from a warmer zone. The source of seed plays an important role in seed-propagated species. As much as possible, buy plants that were grown from seed collected in your soil and climate types. Deer resistance can be an important factor in tree selection in some areas. Table 17-8 lists some commonly available woody plants that deer do not like to eat.
Avoid purchasing weedy trees. Some trees are very fast-growing, but the result is a weak tree. Willow trees, for example, grow very rapidly, averaging 3 to 4 feet of growth per year. However, their branches shed readily in winds and storms, and leaves, twigs, and branches drop throughout the season. Other trees are considered weedy when they release a multitude of seeds that exhibit a high degree of germination. Unwanted tree seedlings emerge in flower beds, lawns, and vegetable gardens. Table 17-9 (see page 450) lists some trees and shrubs that can become weedy or invasive in some areas. For some species, there are improved cultivars that display superior performance and may thus not be considered weedy. It is best to consult local extension personnel or nursery professionals for guidance.
Many woody plants used for ornamental purposes have originated in the region where they are grown. Others have been introduced from Europe, Asia, Australia, Africa, and South America. The introduced plants owe a large portion of their success in exotic environments to their adaptability. However, native plants are also adaptable and may be more likely to adapt to the soil characteristics of their place of origin. Understanding the native habitat of woody plants can be key to growing healthy plants in the landscape environment. Shade-loving plants should not be grown in full sun; upland plants do not tolerate wet feet. It is important to learn where a plant originated and what the soil and climate characteristics are, especially characteristics such as soil moisture and prevailing temperatures, before selecting a tree for a specific use. In this way, mistakes that result in the loss of trees in a few years can be avoided.
If you are purchasing a tree for its ornamental fruit or flowers, be aware of fruit drop. Many trees drop their fruits and even seeds, over sidewalks, on cars, and at entryways to homes. The result is a continual mess as plant parts are tracked inside the home. If you must have such a plant, locate it farther away from the entryway and driveway, or parking area. Other trees, such as mulberries, produce fruits that birds love to eat. Use these with caution!
When selecting a shrub, the branch structure is often less important than it is for trees. Some factors to consider are weediness or invasiveness, pest and disease resistance, dwarf versus standard size (available in a limited number of species), and shade or sun preference. Most ornamental shrubs are valued for their showy flowers. Some of these, such as roses (Rosa spp.) and rose of Sharon (Hibiscus syriacus), are available in a variety of colors. Others are available only in white, such as smooth leaf hydrangea (Hydrangea arborescens) and common mockorange (Philadelphus coronarius) or yellow such as Japanese kerria (Kerria japonica), or other single colors. Some shrubs, such as Tatarian dogwood (Cornus alba), and wintercreeper (Euonymus fortunei) are available with variegated leaves (Fig. 17-18). Shrubs that are used for their "greenness" include evergreens such as yews and junipers and deciduous shrubs such as privet and boxwood (some boxwoods are evergreen) (Fig. 17-19).
BUYING A TREE OR SHRUB: HOW PLANTS ARE SOLD
Woody plants are available in several different ways: balled and burlapped, bare root, bag grown, container grown and field potted, or mechanically transplanted. The method of growing trees is directly related to the production methods used at the nursery where they are grown. Some trees cannot be grown as well in containers as in the field, while others will not obtain the desired size and height unless grown in the field. The different growing methods are discussed in more detail later.
Balled and Burlapped
Balled-and-burlapped trees have been grown for a period of several years in the ground in nurseries. They are dug up, keeping as much of the root mass intact as possible. This is generally accomplished by digging up a large area around the trunk of the tree, lifting it out of the ground, and placing it on burlap (Fig. 17-20). The burlap is tied around the root ball and the base of the trunk to move the tree with as little disturbance as possible. Trees are handled in this manner during dormancy when the ground is no longer frozen, as in late winter to early spring.
The advantages of using this method are that you have a large, established tree and do not have to wait years for it to begin providing shade or filling in an area. Balled-and-burlapped trees can be moved at any time of year, although summer-transplanted trees must be closely monitored to make sure the root ball does not dry out. The disadvantage is that balled-and-burlapped trees are very heavy. It can be costly to dig and move trees. And when they become quite large, special equipment is necessary. Some larger trees are moved with a tree spade and placed directly into a hole that has been prepared by the same equipment.
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Bare-root trees and shrubs are dug up and have the soil rinsed from the roots. The roots are protected from drying by plastic, hydration gels or some other moisture-retaining substance. The disadvantage of this method is that a tree or shrub can only be handled in this manner during dormancy, so the window of opportunity is limited. The advantage of this method is that the bare-root plant is usually young and is light-weight, making shipping costs lower than those for other methods.
Bag-grown trees are planted in field conditions, but in geotextile fabric bags rather than in the ground. The bags are placed into holes and filled with field soil and the trees are planted in them. The bag acts as a root-pruning system (Fig. 17-21). The advantage of this method is that the root system is not disturbed when planting, and the bag permits a well-developed root system to form. The disadvantage is the bags are more costly than growing directly in the ground.
Container Grown and Field Potted
Woody plants that are grown from a cutting or seed in containers need never have their root systems disturbed. They can be transplanted any time the ground is not frozen. Both evergreen and deciduous plants can be handled this way. Smaller trees that are field-grown and dug up with their root ball may be placed into pots rather than balled and burlapped.
Some trees are simply moved from one location (in a nursery or from a site) to another. This can all be done in a single procedure. First, a tree spade is used to dig a hole at the intended site, then the tree space is driven back to the tree site, the soil is left there, and the tree is dug carried back to the intended site, and placed precisely into the hole. Trees that need to be removed for construction purposes are sometimes saved using this method. The advantage is that the tree can be saved and placed in a more suitable location. The disadvantage is that trees often do not survive transplanting due to the loss of large amounts of roots.
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HOW TO PLANT
Balled and Burlapped
When you receive the balled and burlapped tree, you should handle the plant as little as possible, being careful not to disturb the roots. Do not carry the plant by the trunk, as this will loosen it from the root ball. Support the base of the root ball when moving or carrying it. Have the hole prepared ahead of time. The hole should have a diameter about 12 inches wider than the root ball and the same depth as the root ball. Leave the burlap on the root ball but cut the string that is around the trunk and around the top of the root ball. Cut any wire that is wrapped around the ball. Place the ball along with the cloth into the hole you have prepared. Be sure no wires or strings restrict the root ball. If the burlap is not adequately loosened and the string is cut away, the tree is in danger of having its root system girdled. This results in a poorly growing tree that may eventually die because the root system cannot develop as needed to sustain the growth of the tree.
After you have gently placed the tree in the hole, backfill with some of the soil from the hole and firm it as you go to remove any air pockets. Be sure to plant the tree at the same depth as it was before. You should be able to detect the soil line on the trunk. Continue backfilling with soil to fill in the gaps around the sides of the root ball area and keep the trunk at the proper level.
You may tamp lightly on the soil around the tree to eliminate any air pockets that may have developed during the transplanting process. Do not stomp as this may compact the soil and will surely damage the fine roots and root hairs that are so vital to the tree's successful move. Make a dike around the plant about the diameter of the root ball or slightly larger, about 2 inches high, with some of the loose soil and water the plant in (Fig. 17-22).
Remove any string that may have been tied to hold the branches out of the way. Remove broken branches, second leaders, or other problematic growth at this time; otherwise, it is not necessary to prune. Stake the tree if necessary if conditions are windy. Fertilize lightly and keep the tree adequately watered. The first year is most crucial in establishing a well-developed root system. Once the root system has developed, the tree should be able to obtain the water it needs from the soil.
Bare-root trees can only be safely shipped and transplanted during their dormant season. They should be packaged in a medium that prevents the roots from drying out altogether, because even though they are dormant, they are still living organisms with some basic needs. Sawdust, mulch, potting soil, and so on can be used. The roots should be kept moist. Although plants should not be frozen, cool temperatures are preferable to warm ones as the respiration rate of the tree will be lower. Likewise, keep these trees out of full sun. Before planting, bare-root trees should be soaked in room-temperature water for 2 to 6 hours (Fig. 17-23). Check for girdling or badly kinked roots and remove them to avoid a continuation of the problem after planting, Remove damaged roots as well.
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The planting hole should accommodate the root depth. In the center of the hole, build a cone with soil to drape the roots over, spreading them out as evenly as possible out in all directions. Visually locate the soil line on the trunk and plant at the same level in the new hole. Once the tree has been properly placed, begin backfilling with native soil. Carefully backfill between roots, spreading them out vertically. Place the uppermost root slightly angled down from the soil surface. The roots should not be bent to accommodate too small of a hole, but rather, the hole should be dug wide enough to accommodate the roots. Do not cut the roots, but rather dig a long trench if necessary to accommodate long roots. Stake the tree. Fertilize and irrigate as for other types of trees.
Perhaps the first instruction for planting container-grown trees is to avoid those that are pot bound. Their roots are already growing in a circling fashion, and this inevitably leads to girdling of the trunk after planting in the ground. Also, root-bound container-grown trees often have too many roots on the outer edge of the root ball, rather than evenly distributed throughout the root ball. If you must use such a tree, then make three to four vertical slices from the top to the bottom of the root ball before planting. The slices should be about 1 inch deep.
If upon inspection of a tree after removing it from the container, the root system is well developed and not pot bound, slicing through the root system is not necessary. Water the plant well several hours to a day before removing it from the container so that the root ball holds together for handling during planting. Dig a hole of the same size as the container. It should be the exact depth of the root ball, but wider, to accommodate spreading the roots out and to provide loose, friable soil in the surrounding area where new root growth is desired. Using both hands on the bottom of the root ball, pull the roots out from the bottom to direct them to grow downward into the space provided. Be sure to place the root ball into the hole so that the soil line on the trunk is level with the top of the hole.
Trees and shrubs require varying amounts of maintenance, mainly depending on species. Pruning is required at different levels for shrubs, fruit trees, nut trees, and trees grown for ornamental purposes. It would be wise to familiarize yourself with pruning requirements of a plant before purchasing it. Low-maintenance plants are available, although extra effort may be required to identify and locate them. However, this effort will be worth it in the long run if you prefer not to spend much time working in your yard or garden.
Pruning is a very important maintenance procedure for woody plants. It is also the one that many people know the least about. Pruning is covered in detail in chapter 11, but here are some tips and guidelines:
1. Understand the basics of pruning: why it is done, when it is done, and what the effect will be.
2. Know your plant: how it responds to pruning and any particular hazards or weaknesses in that species (some respond to pruning better than others).
3. Use good-quality tools.
4. Do not top trees! It often leads to their ultimate demise because they cannot recover from the assault on their natural defense system.
Tree removal is usually performed when the tree has become hazardous. Many causes can lead to a hazardous condition. Sometimes the root system has been damaged by compaction or roots have been severed during a construction project or a tree may be declining naturally. Sometimes a tree requires removal because it is in the way of a proposed construction project. Tree removal of larger, older trees, requires the help of a professional. Special equipment such as truck-mounted hydraulic lifts are necessary. Some of the dangers include the presence of electrical power lines, houses, and other structures in the way of branches that must be dropped. Only someone properly trained in safe procedures for tree removal should perform this task.
Stumps can be left to decompose over a period of years. They may also be ground with a stump grinder, which removes the trunk, but leaves the root system, including large lateral roots near the soil surface. Eventually the roots should decompose. However, some tree roots generate shoots along their surface, even after the main trunk has been removed. It may be necessary to apply herbicide to prevent suckering if this is a problem. Herbicide can be painted directly on the stump to prevent suckering as well. The active ingredient in stump herbicides is triclopyr.
Trees may be mulched after planting to help with weed suppression, moisture retention, prevention of soil compaction, and reduced competition with turf. Mulching under a tree eliminates damage done to trunks by lawn mowers and string trimmers.
Mulch should be applied at least out to the dripline of trees. This is the circular line formed by the outermost tips of branches. Each year, as a tree grows, the mulched area should increase. However, mulch should not be in contact with the trunk. Pull mulch at least 6 inches away from the trunk to prevent bark decay. Mulch can be applied at a depth of 2 to 4 inches. If it is deeper than that, it smothers the surface roots. The mulch will slowly decompose over time and will require replacement about once a year.
If wood products are used, be sure you know the source and do not use mulch from diseased trees. If very fresh mulch is used, some feel that microorganisms in the mulch will use soil nitrogen. These microorganisms help to break down organic matter but require nitrogen for their reproduction. This situation can be avoided by adding a low level of nitrogen fertilizer to the mulched area.
It is best to relocate a tree when it is still quite small. When a tree is moved, it is necessary to retain as much of the root system as possible. Although most of the root mass can be dug up within 1 to 3 feet of the tree trunk (depending on tree size), many of the long roots will be severed in the moving process. Yet, the root ball for even a young tree can be quite heavy. A tree spade is used to move larger trees as described earlier in the section on mechanically transplanted. The tree should be cared for as with a newly planted tree, especially with respect to irrigation to ensure new root development as soon as possible. Trees are usually moved in this manner in spring or fall, when mild temperatures prevail.
How to Dig up a Shrub
If you know ahead of time that you want to relocate a shrub in your yard, then you can make preparations during the prior autumn that will reduce shock to the shrub. Prune the roots of the shrub by cutting into the soil with a shovel in a circle around the shrub. You should cut at about the same diameter as the root ball will be when you move the shrub the following spring. This root pruning technique stimulates new root growth within the cut area. In the following spring, dig the hole where the shrub will go. Water the shrub well a day or so before digging it up to ensure that the root ball will hold together. Dig up the shrub, retaining as much of the root ball as possible. Use a tarp to set the root on for transporting it to the new location. Make sure the hole you have dug is large enough to accommodate the entire root ball and then gently place the shrub into the hole. Backfill as necessary to fill in all the spaces and water and fertilize.
Trees and shrubs provide a backbone for the plantings in a home. Woody groundcovers can provide a solution for problematic areas, such as heavy shade or difficult-to-mow areas. Although all of these plants add beauty to any landscape, they also serve other functions, such as providing windbreaks, shade for the home, and habitats for wildlife. Problems can arise, however, when a tree or shrub is planted in the wrong place. This happens, for example, when trees that will mature to a large size are planted too close to power lines or buildings. Common problems with trees in urban settings are restricted root areas and damage to tree roots due to construction. Rototilling under trees to plant flowers or other plants also damages many of the important feeder roots that grow near the soil surface.
Trees, shrubs, and groundcovers should be selected for the site where they will be planted. Practices to grow and maintain a healthy tree begin with selection of a healthy plant, followed by proper training and pruning, proper cultural practices, and minimizing stress to the plant.
Trees and shrubs are available as bare-root, balled-and-burlapped, or container-grown plants. Vines and groundcovers are generally available as container-grown plants. All of these may be purchased and planted at various times of year, although the dormant season is the best time to plant a deciduous tree or shrub. Balled-and-burlapped and container-grown trees may be planted any time of year, but special care must be taken during times of high heat and low rainfall. By selecting the right plant for the site, giving consideration to root structure, maintenance needs, and selection of a healthy plant, a woody plant may become part of the landscape for a very long time. It will thus fulfill its aesthetic or utilitarian function throughout its lifetime.
* Develop a top 20 list of trees and one for shrubs that are particularly suited for your area. Include features such as size and shape, sun and shade requirements, soil requirements, and diseases or other common problems. Identify one or more aesthetic qualities about each plant.
* Research and identify native trees and shrubs that grow in challenging sites in your geographical area: wet, dry, slopes, poor soils, and shade.
* Take a plant identification walk with an instructor or woody plant professional in your area. Learn to identify plants from a distance, and take note of the conditions in which they thrive or struggle. Learn to recognize common problems of woody landscape plants: poor placement, disease susceptibility, mismanagement, and others.
1. Name three ways that trees provide practical solutions.
2. What is the definition of a specimen tree?
3. The people whose job it is to monitor the health of trees and care for them are called--.
4. Describe the effect on trees of rototilling under them.
5. Landscape plants that are used around the base of a home are called--.
6. Name three places or situations in which groundcovers are particularly useful.
7. What is the main problem with fast-growing trees?
8. What are the advantages and disadvantages of balled-and-burlapped trees?
9. What are the advantages and disadvantages of container-grown and bag-grown trees?
10. What are the advantages and disadvantages of bare-root trees?
Bridwell, F. M. (1994). Landscape plants: their identification, culture, and use. Clifton Park, NY: Thomson Delmar Learning.
Dirr, M. A. (1975). Manual of woody landscape plants. Champaign, IL: Stipes.
Gilman, E. F. (1997). Trees for urban and suburban landscapes. Albany, NY: Thomson Delmar Learning.
Shigo, A. L. (1995). 100 tree myths. Denham, NH: Shigo and Trees, Associates.
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 17-1 Deep- and Shallow-Rooted Trees COMMON SPECIES DEPTH Bald cypress Taxodium distichum Deep Beech Fagus spp. Shallow Birch Betula spp. Shallow Black tupelo Nyssa sylvatica Deep Cottonwood Populus deltoides Shallow Crape myrtle Lagerstroemia indicans Shallow Hackberry Celtis occidentalis Shallow Hickory Carya spp. Deep Hornbeam Carpinus spp. Deep Kentucky yellowwood Cladastris kentuckea Deep Loblolly pine Pinus taeda Deep Norway maple Acer platanoides Shallow Oak Quercus spp. Deep Olive Olea spp. Deep Silver maple Acer saccharinum Shallow Spruce Picea spp. Shallow Sugar maple Acer saccharum Shallow TABLE 17-2 Ornamental Shrubs for the Landscape COMMON NAME SPECIES ZONES Alpine currant Ribes alpinum 2-7 American cranberrybush Viburnum trilobum 2-7 viburnum Amur privet Ligustrum amurense 4-7 Arrowwood viburnum Viburnum dentatum 3-8 Azalea Rhododendron spp. 5-9 Bearberry cotoneaster Cotoneaster dammeri 5-7 Black chokeberry Aronia melanocarpa 3-8 Bumald spiraea Spiraea x bumalda 3-8 Burkwood viburnum Viburnum x burkwoodii 5-8 Bush cinquefoil Potentilla fruticosa 2-6 Buttonbush Cephalanthus occidentalis 5-11 Carolina allspice Calycanthus floridus 4-9 Chenault coralberry Symphoricarpos x 4-7 chenaultii Chengtu lilac Syringa swenginzowii 5-6 Common box Buxus sempervirens 5-8 Common flowering Chaenomeles speciose 4-8 quince Common lilac Syringa vulgaris 3-7 Common mock orange Philadelphus coronarius 4-8 Common ninebark Physocarpus opulifolius 2-7 Common snowberry Symphoricarpos albus 3-7 Common winterberry Ilex verticillata 3-9 Doublefile viburnum Viburnum plicatum var. 5-7 tomentosum Dwarf fothergilla Fothergilla gardenii 5-8 Dwarf Korean lilac Syringa meyeri 3-7 European cranberrybush Viburnum opulus 3-8 viburnum Flowering almond Prunus triloba 3-6 Forsythia Forsythia x intermedia 5-9 Fragrant sumac Rhus aromatica 3-9 Goldflame honeysuckle Lonicera x heckrottii 5-9 Indiancurrant coralberry Symphoricarpos orbiculatus 2-7 Japanese barberry Bereberis thunbergii 4-8 Japanese flowering quince Chaenomeles japonica 5-8 Japanese privet Ligustrum japonicum 7-10 Japanese tree lilac Syringa reticulata 3-7 Judd viburnum Viburnum x juddii 4-8 Kerria, black jetbead Rhodotypos scandens 4-8 Koreanspice viburnum Viburnum carlesii 5-8 Littleleaf box Buxus microphylla 6-9 Littleleaf lilac Syringa microphylla 4-7 Mentor barberry Bereberis x mentorensis 5-8 Meserve holly Ilex x meservae 4-7 Oakleaf hydrangea Hydrangea quercifolia 5-9 Oregon grapeholly Mahonia aquifolium 5-8 Panicle hydrangea Hydrangea paniculata 3-8 Purple beautyberry Callicarpa dichotoma 5-8 Red chokeberry Aronia arbutifolia 4-9 Rhododendron Rhododendron spp. 4-8 Rockspray Cotoneaster horizontalis 5-7 Rugose rose Rosa rugosa 2-7 Sapphireberry Symplocos paniculata 4-8 Scarlet firethorn Pyracantha coccinea 5-9 Shrub rose Rosa spp. 4-5 Smooth hydrangea Hydrangea arborescens 4-9 Spreading cotoneaster Cotoneaster divaricatus 4-7 Summersweet Clethra alnifolia 4-9 Tatarian dogwood Cornus alba 3-7 Trumpet honeysuckle, Lonicera sempervirens 4-9 coral honeysuckle Vanhoutte spiraea Spiraea x vanhouttei 3-8 Wayfaringtree viburnum Viburnum lantana 4-7 Weigela Weigela florida 5-8 Winged euonymus Euonymus alatus 4-8 Winter honeysuckle Lonicera fragrantissima 4-8 Wintercreeper euonymus Euonymus fortunei 5-8 TABLE 17-3 Ornamental Qualities of Groundcovers COMMON SPECIES ORNAMENTAL QUALITY ZONES Bearberry Arctostaphylos Glossy-leaved, matted 3-7 uvaursi groundcover Bunchberry Cornus Deciduous matted 2-5 canadensis groundcover, lustrous dark green leaves, small red fruit in fall Canby Paxistima Evergreen groundcover 4-7 paxistima canbyi Cotoneaster Cotoneaster Several species of low- 4-7 species spp. growing shrubby groundcovers with arching, spreading branches Creeping Juniperus Dense, mat-like ever- 3-9 juniper horizontalis green shrub; very low-growing Creeping Liriope spicata Grass-like clumps with 5-9 lilyturf purple spikes of flowers in spring Creeping Gaultheria Evergreen, low 5-8 winter- procumbens spreading groundcover; green glossy, minty-scented leaves; fruit is large, red capsule Dwarf Stephandra Dissected, crinkly 4-8 cutleaf incisa foliage; tough, 3 stephandra 'Crispa' feet tall spreading, slightly mounded groundcover, foundation shrub; drapes over walls. Honeysuckle Lonicera spp. Fast-growing vine with 3-9 species tubular flowers of cream, yellow, red, or orange Indiancurrant Symphoricarpos Spreading, arching shrub, 3-6 coralberry orbiculatus red fruits in fall Labrador tea Ledum Evergreen, dwarf, white 2-6 groenlandicum flowers in spring Savin juniper Juniperus Evergreen, wide-spreading 3-7 sabina vase-shaped blue-green shrub Sweetgale Myrica gale Glossy blue-green 1-6 fragrant foliage, low shrub Trailing Epigaea repens Evergreen, low-growing 3-8 arbutus shrub Vinca Vinca minor Shade-loving groundcover 4-8 with small purple flowers in spring Wintercreeper Euonymus Creeping groundcover or 5-8 fortunei bushy plant with slender stems that require support to climb; leaf variegations numerous Yellowroot Xanthorhiza Matted groundcover, 3-9 simplicissima yellow bark, bright green in summer, yellow in fall TABLE 17-4 Trees, Shrubs, Vines, and Groundcovers for Problematic Soil Conditions COMMON SPECIES ZONE Dry Trees American beech Fagus grandiflora 4-9 Chinese juniper Juniperus chinensis 3-8 Colorado spruce Picea pungens 3-7 European mountainash Sorbus aucuparia 3-7 European white birch Betula pendula 3-5 Hedge maple Acer campestre 5-8 Japanese maple Acer palmatum 5-9 Norway maple Acer platanoides 4-7 Pin oak Quercus palustris 4-9 Quaking aspen Populus tremuloides 2-6 Swiss mountain pine Pinus mugo 3-7 Swiss stone pine Pinus cembra 3-6 Shrubs Alpine currant Ribes alpinum 3-7 Burning bush Euonymus alatus 4-8 Bush cinquefoil Potentilla cinquefolia 2-7 Common flowering quince Chaenomeles speciose 4-9 Dwarf Eastern white pine Pinus strobus 'Nana' 3-7 Eastern ninebark Physocarpus opulifolius 3-6 Japanese kerria Kerria japonica 5-9 Mentor barberry Berberis x mentorensis 5-9 Mountain pieris Pieris floribunda 5-7 Redvein enkianthus Enkianthus campanulatus 5-8 Rockspray cotoneaster Cotoneaster hortizontalis 5-8 Rosemary Rosmarinus officinalis 7-10 Spreading cotoneaster Cotoneaster divaricatus 5-8 Thunberg spiraea Spiraea thunbergii 4-9 Vanhoutte spiraea Spiraea vanhouttei 3-8 Yucca species Yucca spp. 4-9 Vines and Groundcovers Bearberry Arctostaphylos uva-ursi 3-7 Creeping juniper Juniperus horizontalis 3-9 Honeysuckle species Lonicera spp. 3-9 Indiancurrant coralberry Symphoricarpos orbiculatus 3-6 Scarlet clematis Clematis texensis 4-8 Wet Trees Catalpa Catalpa spp. 4-9 Dawn redwood Metasequoia 5-9 glyptostroboides Eastern arborvitae Thuja occidentalis 3-7 Green ash Fraxinus pennsylvanica 3-9 Pawpaw Asimina triloba 5-8 Pecan Carya illinoinensis 5-9 Quaking aspen Populus tremuloides 2-6 Red maple cultivars Acer rubrum 3-9 River birch Betula nigra 4-9 Sweetbay magnolia Magnolia virginiana 5-9 Sweetgum Liquidambar styraciflua 5-9 White willow Salix alba 3-9 Shrubs Arrowwood viburnum Viburnum dentatum 4-9 Blackhaw viburnum Viburnum prunifolium 3-9 Chokeberry species Aronia spp. 3-9 Eastern ninebark Physocarpus opulifolius 3-6 European pussywillow Salix caprea 3-9 Fothergilla species Fothergilla spp. 5-9 Gray dogwood Cornus racemosa 3-7 Japanese kerria Kerria japonica 5-9 Oakleaf hydrangea Hydrangea quercifolia 5-9 Redosier dogwood Cornus stolonifera (Cornus 3-8 sericea) Smooth hydrangea Hydrangea arborescens 4-9 Tartarian dogwood Cornus alba 3-8 Virginia sweetspire Itea virginica 6-9 White fringetree Chionanthus virginicus 5-9 Winterberry Ilex verticillata 4-9 Vines and Groundcovers Climbing hydrangea Hydrangea petiolaris 5-7 Creeping lilyturf Liriope spicata 5-9 Dwarf cutleaf stephandra Stephandra incisa 'Crispa' 5-8 Gray willow Salix repens 4-9 Indiancurrant coralberry Symphoricarpos orbiculatus 2-7 Labrador tea Ledum groenlandicum 2-6 Acid Trees American holly Ilex opaca 6-9 Blue ash Fraxinus quadrangulata 4-8 Eastern white pine Pinus strobus 3-9 Flowering dogwood Cornus florida 5-8 Franklin tree or Ben Franklinia alatamaha 6-7 Franklin tree Freeman hybrid maple Acer x freemanii 3-9 Green ash Fraxinus pennsylvanica 3-9 Trees Hedge maple Acer campestre 5-8 Japanese maple Acer palmatum 5-9 Kousa dogwood Cornus kousa 5-7 Norway spruce Picea abies 3-8 Pin oak Quercus palustris 4-9 Scarlet oak Quercus coccinea 5-9 Sour gum Nyssa sylvatica 5-9 Sourwood Oxydendrum arboreum 5-9 Swiss stone pine Pinus cembra 3-6 White oak Quercus alba 4-9 Willow oak Quercus phellos 6-9 Shrubs Carolina rhododendron Rhododendron 5-7 carolinianum Catawba rhododendron Rhododendron catawbiense 4-7 Corneliancherry dogwood Cornus mas 5-8 Dwarf and large fothergilla Fothergilla gardenii, 5-9 Fothergilla major Flame azalea Rhododendron 5-8 calendulaceum Highbush blueberry Vaccinium corymbosum 4-9 Japanese pieris, Japanese Pieris japonica 6-8 andromeda Korean rhododendron Rhododendron 5-7 mucronulatum Meserve holly Ilex x meservae 5-8 Mountain laurel Kalmia latifolia 5-9 Mountain pieris Pieris floribunda 5-7 Pagoda dogwood Cornus alternifolia 4-7 Pearlbush Exochorda racemosa 5-9 Red and black chokeberry Aronia arbutifolia, Aronia 3-9 melanocarpa Redvein enkianthus Enkianthus campanulatus 4-7 Sheep laurel Kalmia angustifolia 2-7 Summersweet clethra Clethra alnifolia 3-7 Viburnum species Viburnum spp. 3-8 Vines and Groundcovers Bunchberry Cornus canadensis 2-5 Highbush blueberry Vaccinium corymbosum 5-8 Lowbush blueberry Vaccinium angustifolium 2-5 Sargent's weeping Tsuga canadensis 'Pendula' 4-8 hemlock Trailing arbutus Epigaea repens 3-8 Alkaline Trees Allegheny serviceberry Amelanchier laevis 4-8 American mountainash Sorbus americana 2-6 Black walnut Juglans nigra 4-9 Blue ash Fraxinus quadrangulata 4-7 Northern catalpa Catalpa speciosa 4-8 Chinese juniper Juniperus chinensis 4-9 Crabapples Malus spp. 5-9 Cucumbertree magnolia Magnolia acuminata 4-8 Dogwood species Cornus spp. 3-7 Downy serviceberry Amelanchier arborea 4-9 Eastern arborvitae Thuja occidentalis 3-7 Eastern redbud Cercis canadensis 4-9 European alder Alnus glutinosa 4-7 Goldenraintree Koelreuteria paniculata 5-9 Trees Common hackberry Celtis occidentalis 3-9 Hawthorn species Crataegus spp. 4-7 Kentucky coffeetree Gymnocladus dioica 4-7 Ohio buckeye Aesculus glabra 4-7 Pecan Carya illinoinensis 5-9 Quaking aspen Populus tremuloides 2-6 Saucer magnolia Magnolia soulangiana 5-9 Shagbark hickory Carya ovata 4-8 Shingle oak Quercus imbricaria 5-9 Spruce Picea spp. 4-8 Sweetgum Liquidambar styraciflua 5-9 White fir Abies concolor 4-7 White oak Quercus alba 4-9 Shrubs Bottlebrush buckeye Aesculus parviflora 5-9 Butterflybush Buddleia davidii 4-8 Crape myrtle Lagerstroemia indicans 7-9 Flowering quince Chaenomeles speciosa 4-9 Hydrangea species Hydrangea spp. 4-9 Jetbead Rhodotypos scandens 5-8 Lilac species Syringa spp. 3-8 Serviceberry Amelanchier canadensis 4-8 Showy forsythia Forsythia intermedia 5-8 Smokebush Cotinus coggygria 5-7 Weigela Weigela florida 5-9 Yucca Yucca spp. 4-9 Vines and Groundcovers Australian saltbush Atriplex semibaccata 4-5 TABLE 17-5 Trees, Shrubs, Vines, and Groundcovers for Shade COMMON SPECIES ZONE Trees Canadian hemlock Tsuga canadensis 3-7 Flowering dogwood Cornus florida 5-9 Japanese maple Acer palmatum 5-8 Pagoda dogwood Cornus alternifolia 3-7 Redbud Cercis canadensis 4-9 Witchhazel Hamamelis spp. 4-8 Shrubs Gray dogwood Cornus racemosa 3-8 Hydrangea species Hydrangea spp. 4-9 Japanese kerria Kerria japonica 4-9 Nannyberry viburnum Viburnum lentago 3-7 Oregon grapeholly Mahonia aquifollium 5-8 Rhododendron species Rhododendron spp. 5-9 Yew Taxus baccata 6-7 Vines and Groundcovers English ivy Hedera helix 4-9 Vinca Vinca minor 4-8 Virginia creeper Parthenocissus quinquefolia 4-9 Wintercreeper Euonymus fortunei 5-9 TABLE 17-6 Small Ornamental Trees (Under 25 Feet) COMMON NAME SPECIES ZONES Apple serviceberry Amelanchier x grandiflora 4-9 Autumn-olive Elaeagnus umbellata 4-8 Blireiana plum Prunus x blireiana 5-9 Corneliancherry Cornus mas 4-7 dogwood Crabapples Malus hybrida 4-8 Crape myrtle Lagerstroemia indicans 7-10 Desert willow Chilopsis linearis 7-10 Eastern redbud Cercis canadensis 4-9 Feathery buckthorn Rhamnus frangula 3-7 Florida maple, Southern Acer barbatum 7-9 sugar maple Flowering dogwood Cornus florida 5-9 Franklin tree, Ben Franklinia alatamaha 6-9 Franklin tree Fullmoon maple Acer japonicum 5-7 Goldenchain tree Laburnum x watereri 5-7 Green hawthorn Crataegus viridis 4-7 Japanese apricot Prunus mume 6-9 Japanese maple Acer palmatum 5-8 Korean stewartia Stewartia koreana 5-8 Kousa dogwood Cornus kousa 5-8 Kwanzan cherry Prunus serrulata 'Kwanzan' 6-9 Lily magnolia Magnolia liliiflora 5-8 Mimosa tree, silk tree Albizia julibrissin 6-9 Pagoda dogwood Cornus alternifolia 3-7 Purpleleaf plum Prunus cerasifera 4-9 Sand cherry Prunus x cistena 3-7 Saucer magnolia Magnolia soulangiana 5-9 Shogetsu cherry Prunus serrulata 'Shogetsu' 5-9 Smoketree Cotinus coggygria 5-8 Star magnolia Magnolia stellata 5-9 Threadleaf falsecypress, Chamaecyparis pisifera 4-8 Japanese falsecypress Trident maple Acer buergeranum 5-9 Weeping blue atlas cedar Cedrus atlantica 6-9 Weeping cherry, weeping Prunus subhirtella 'Pendula' 5-8 Higan cherry Weeping Katsura tree Cercidiphyllum japonicum 5-8 'Pendula' Witchhazel Hamamelis virginiana 3-8 TABLE 17-7 Ornamental Shade Trees COMMON SPECIES ZONE American linden Tilia americana 2-8 American sweetgum Liquidambar 5-9 styraciflua Amur corktree Phellodendron 4-7 amurense Common hackberry Celtis occidentalis 2-9 Cucumber magnolia Magnolia acuminata 4-8 Freeman maple Acer x freemanii 3-8 Ginkgo (male trees) Ginkgo biloba 4-8 Goldenraintree Koelreuteria 5-9 paniculata Honeylocust- Gleditsia 3-9 thornless triacanthos Japanese zelkova Zelkova serrata 6-9 Littleleaf linden Tilia cordata 3-7 Northern red oak Quercus rubra 3-9 Norway maple Acer platanoides 3-8 Red maple Acer rubrum 3-9 Sour gum, black gum Nyssa sylvatica 5-9 Sugar maple Acer saccharum 3-8 Tuliptree Liriodendron 5-9 tulipifera White ash Fraxinus americana 3-9 White oak Quercus alba 4-9 TABLE 17-8 Woody Plants Deer Do Not Like COMMON SPECIES ZONES Trees Ash Fraxinus spp. 3-9 Cedar Cedrus spp. 6-9 Coast redwood Sequoia sempervirens 7-9 Cypress Cupressus spp. 7-9 Douglas fir Pseudotsuga 4-6 menziesii False cypress Chamaecyparis spp. 4-8 Fig Ficus carica 7-9 Fir Abies spp. Varies Hackberry Celtis occidentalis 3-9 Hawthorn Crataegus spp. 4-7 Japanese maple Acer palmatum 5-8 Magnolia Magnolia spp. 5-9 Maidenhair tree, Ginkgo biloba 4-8 ginkgo Oak Quercus spp. 3-10 Pine Pinus spp. 2-7 Silk tree Albizia julibrissin 6-9 Spruce Picea spp. 2-7 Shrubs Barberry Berberis spp. 3-8 Bottlebrush Callistemon spp. 8-11 Boxwood Buxus spp. 6-9 Butterflybush Buddleia davidii 5-9 California buckeye Aesculus californica 7-8 Cotoneaster Cotoneaster spp. 4-7 Currant Ribes spp. 2-7 Elaeagnus Elaeagnus spp. 2-8 Firethorn Pyracantha coccinea 6-9 Shrubs Flowering quince Chaenomeles spp. 4-8 Glossy abelia Abelia x 6-9 grandiflora Heath Erica spp. 5-7 Heavenly bamboo Nandina domestica 6-9 Holly Ilex spp. 3-9 Japanese kerria Kerria japonica 4-9 Juniper Juniperus spp. 2-9 Lilac Syringa spp. 3-7 Myrtle Myrtus communis 9-10 Oleander Nerium oleander 8-11 Oregon grape holly Mahonia aquifolium 5-7 Scotch heather Calluna vulgaris 4-6 St. Johns wort Hypericum spp. 4-8 Sumac Rhus spp. 3-9 Sweet box Sarcococca 6-8 hookeriana Viburnum Viburnum spp. 3-7 TABLE 17-9 Weedy Trees and Shrubs NAME BOTANICAL NAME ZONES Amur honeysuckle Lonicera maackii 3-8 Amur maple Acer ginnala 3-8 Amur privet Ligustrum amurense 4-7 Autumn-olive Elaeagnus umbellata 2-7 Boxelder Acer negundo 3-9 Chinese elm Ulmus parvifolia 5-9 Common chokecherry Prunus virginiana 2-6 Eastern cottonwood Populus deltoides 4-9 Eucalyptus Eucalyptus spp. 7-10 (some species) European alder Alnus glutinosa 4-7 Multiflora rose Rosa multiflora 5-8 Russian mulberry Morus alba var. 5-8 tatarica Russian-olive Elaeagnus 2-7 angustifolia Siberian elm Ulmus pumila 4-9 Silver maple Acer saccharinum 3-9 Weeping willow Salix alba 'Tristis' 2-8
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|Author:||Loehrlein, Marietta M.|
|Publication:||Home Horticulture: Principles and Practices|
|Date:||Jan 1, 2008|
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|Next Article:||Chapter 18: landscape design, installation, and maintenance.|