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Chapter 20 Installing landscape plants.


Upon completion of this chapter, you should be able to

* identify the tools used in the installation of landscape plants

* condition soil used in the installation of landscape plants

* describe the advantages and disadvantages of bare-rooted, balled and burlapped, and containerized plant material

* select the best season for transplanting

* outline procedures for the installation of trees, shrubs, groundcovers, bedding plants, and bulbs

* describe the advantages and disadvantages of organic and inorganic mulches

* explain the benefits of antitranspirants

* describe installation problems unique to the American Southwest and Southeast

The Importance of Proper Installation

High-quality landscapes begin with top-quality plant materials. Both depend upon careful installation techniques to assure the survival and growth of the transplanted stock. Landscape contractors joke about $25 plants set into $75 holes. In fact, a great deal of labor and materials are often needed to prepare a hostile planting site for a new plant.

Few sites offer a perfect combination of proper soil texture, fertility, and pH with correct drainage and optimum water and humidity throughout the post-transplant period. All are necessary for successful transplanting.

The Necessary Tools

Since the plant material to be installed includes seeds, bedding plants, groundcovers, and trees and shrubs of all sizes, a wide range of tools must be available to accomplish the installation. The hand tools most commonly used are shown and described in Appendix B.

As plant materials increase in size, hand tools must be supplemented with power tools. The tree spade makes possible the successful transplant of large trees and shrubs, Figure 20-1. It operates on a hydraulic system, with each movement controlled from a set of levers that permits the machine to be operated by anyone, regardless of physical strength. Other power tools helpful in the installation of landscape plants include the power auger, power tiller, tractor, and front-end loader.

The Soil for Installation

It is best to use existing soil of the site to assure the most successful transplanting of trees and shrubs. Research has shown that plant roots adapt faster and grow deeper under those conditions. However, the soil removed from a planting hole may be unsatisfactory in its unaltered state for use as replacement (or backfill) soil after the new plant is set. It may be too heavy with clay and need the addition of sand and peat moss to provide better aeration and flocculation (aggregation of soil particles). There may be too much sand, requiring addition of humus to retain moisture around the new plant's roots. Landscapers may have to deal with the hard caliche layer if in the Southwest, salt-saturated soil next to roadways and walks, construction debris buried by builders, and the natural stoniness of rocky regions. Rich loam with ideal pH and good drainage is not common on most sites, where the landscaper is usually one of the last developers to be called in.


The soil to be filled into the planting hole must provide a medium in which the root system of the new plant can resume growth and develop fibrous root hairs to absorb water and nutrients for the new plant. If the soil does not drain adequately, the new plant may die from a lack of oxygen. If the backfill is too sandy, the new roots of the plant will stay within its soil ball and not grow out into the new soil.

Correct soil for plant installation has these qualities:

* Loamy texture (near equal mix of sand, peat, and soil)

* Good drainage

* Suitable pH

* Balanced nutrients

These qualities may be attained by blending conditioners such as sand, peat moss, compost, leaf mold, and manure with the soil before backfilling. In some situations, the original soil may be so unsatisfactory that it must be completely replaced, although recent research suggests that this is seldom necessary. In large landscape installations, the conditioning needs should be determined in advance so that necessary quantities of the additives can be ordered and available at the planting site. All members of the planting crew should be instructed in how to prepare the backfill mix. Periodic checks by the crew supervisor will assure that the new soil is mixed correctly and uniformly.

Root Forms of Landscape Plants

Landscape plants are available in a variety of root forms. Bedding plants and groundcovers are usually grown in pressed peat pots or plastic packets that permit the root system to be transplanted intact. Trees and shrubs can be purchased as bare-rooted, balled and burlapped (B & B), or containerized plants. The advantages and disadvantages of each are compared in Figure 20-2.

Which root form is best to use depends upon the season of the year, the availability of stock, the size of the plants at the time of installation, and the budget of the project. Bare-root is a common root form for deciduous shrubs and a few trees that develop new roots quickly after transplanting.

Evergreens are most often balled and burlapped or containerized. Deciduous trees and shrubs may also be obtained in B & B or containerized forms. Vines are usually containerized.

The Time to Transplant

The best season for transplanting depends upon the type of material being planted. Usually, the prime objective is to transplant at a time that will permit good root growth before shoots and leaves develop. For most plants in most parts of the country, that time is early autumn. Then the roots can grow as long as the soil remains unfrozen, while the cool air temperatures encourage the above-ground parts to go dormant. Early spring, when root growth exceeds shoot growth, is the second best season. Summer is not a good season unless containerized material is used, with its intact root system. Winter is not a good season for transplanting in northern regions because the roots cannot grow. In regions where the winter temperatures are milder and the ground doesn't freeze, winter can be a satisfactory alternate season for transplanting.

Flowering bulbs have definite transplant seasons. Hardy bulbs, which bloom in the spring, must be planted in the fall. Tender bulbs, which flower in the summer and will not survive the winter, are planted in the spring, dug up in the fall, and stored indoors over winter.

Annual flowers, purchased as bedding plants, are transplanted in the spring after all danger of frost is past. In regions where the fall season is long and mild, a second planting of cool season annuals may occur after the hot temperatures of summer are past.

Methods of Installation

Trees and Shrubs

Assuming that the plants being installed are suited to the site and in good health, the next most critical factor in their success is proper planting procedure. The ultimate objective of correct installation is to minimize transplant shock (stress) and return the plant to a normal state of growth as quickly as possible. Differences in technique based on regional geography are minimal. While those differences will be noted here, the basic methods of installation described are nearly the same throughout the country. Variations in technique are more related to the root form of the plants and whether they have a spreading root system or a tap root than anything else.

Bare-Rooted Plants. These plants are likely to be small and deciduous at the time of their transplant. They should be installed in planting pits that are either flat bottomed (for plants with a tap root) or mounded (for plants with a spreading root system), Figure 20-3. Roots should be spread out from the center and over the mound to approximate their natural habit of growth. The planting pit needs to be wide enough to avoid cramping the roots, and the earth mound should be firmly packed to prevent settling. Settling would allow the plant to sink below grade level and lessen its chance of survival. There is usually a soil stain on the bark of the plant to indicate the level at which it was growing before harvest. It should not be planted deeper than that level when transplanted.

Containerized Plants. The first thing to be done when installing containerized plants is to remove the container and determine the condition of the root system. The plant may have been harvested as a bare-root plant and only recently placed in the container, not having sufficient time to produce new roots. It needs to be installed like a bare-root plant. Conversely, the plant may have been in the container too long, causing its roots to grow around themselves. This condition is termed pot-bound, and the plants will have to be either unwound before planting or given several vertical cuts through the root mass to induce new root growth that is oriented properly, Figure 20-4. Another technique used to overcome the girdling tendency in some containerized plants is butterflying. It requires the soil ball to be split halfway up its center so that the root system can be spread apart (like butterfly wings) when placed into the planting hole. If the potentially girdling roots are in the top half of the root mass, butterflying will not help. However, where applicable, the technique can promote a more natural root orientation in the new transplant. Ideally, the plants will have been grown in the container for a proper period of time and will be ready to place into their flat-bottomed pit with minimal disturbance to their established root system. Even with containerized plants that are not pot-bound, it is good to loosen the roots a bit before placing them in the pit.



Balled and Burlapped Plants. Nearly all large trees and shrubs are balled and burlapped at the time of their harvest. Some will be wrapped in biodegradable burlap that need not be removed when planted. Some will be wrapped in treated or synthetic burlap that should be removed as much as possible after the plant is set into the pit. Either type of burlap may be secured with non-biodegradable rope or twine that must be removed once the plant is in the pit. Not removing the rope or twine could result in the eventual girdling of the plant, if the ties encircle the trunk of a tree or the crown of a shrub. Girdling prevents nutrients from moving from the roots to the canopy of the plant, causing it to starve and die. Very large balled and burlapped plants may be placed in wire baskets at the nursery to prevent the soil ball from breaking. If it is possible to do without disturbing the soil ball, the basket should be cut away before planting. If that is not possible, then minimally the upper rows of wire should be cut away once the plant is positioned in the planting pit.

The planting pit for balled and burlapped trees and shrubs should be flat bottomed. It should be no deeper than the height of the root ball in order to allow the plant ball to rest on a solid base. There should be no allowance for soft backfill beneath the soil ball--otherwise it will settle, making the transplant too deep, Figure 20-5. In areas of the country where drainage is poor and/or the soil is heavy with clay, it is recommended that the depth of the planting pit be less than the height of the soil ball to permit 3 to 5 inches of the soil ball to extend above grade. Pit width is a much different story. The intent is to assure that the roots grow horizontally out from the plant and eventually into the surrounding undisturbed soil. Accordingly, the planting pit should be at least twice as wide as the soil ball, and on sites where the soil is compacted, the planting hole should be increased to three or more times the diameter of the soil ball. The same applies to the width of trenches used for hedge plantings.

Correct Backfilling. Backfill is the soil returned to the planting pit after the plant is set. The soil interface is the place where the backfill meets both the soil ball or roots of the transplant and the sides of the planting hole. If the backfill soil is significantly different from either the soil in which the plant has been growing or the surrounding soil in texture, moisture content, aeration, or added amendments, the transplant may be negatively affected. For example, if the backfill is amended to become finer textured than the soil in the root ball, it creates an underground sponge that quickly pulls water away from the root ball and holds it where the plant cannot reach it. If the backfill is more conducive for root growth than the surrounding soil, many root systems will not develop properly. They will stay within the planting hole and not spread wide and deep as they should. Therefore, for most planting situations, the backfilling should either be done using soil removed from the hole or with soil that closely matches the original soil in texture and other attributes.

As backfill is added, care should be taken to avoid leaving air pockets within the planting pit. Bare-root plants should have the soil worked under and into the root mass to eliminate air space. The persons doing the installation should use their feet to tamp down the soil around the soil ball of containerized and B&B materials. Just enough pressure should be applied to eliminate the air pockets while avoiding compaction of the backfill. Balled and burlapped plants should have the fabric being buried tucked down into the pit. If permitted to extend above the backfill it will serve as a wick to evaporate water away from the plant roots and promote undesirable drying.


Watering can be done as the backfill is added, but the creation of a muddy pit that will encase the root system in a glazed shell after drying should be avoided. For trees and larger shrubs, the excess soil can be used to create a mounded ring over the root zone to catch and hold water. In large landscapes, such as golf courses, parks, or highway plantings, the soil ring may determine whether the transplants survive during the first year when moisture is especially critical. In northern regions, these soil rings should be removed at the onset of winter to avoid repeated freezing and thawing that can injure the plants at their base.

Staking and Guying. Once installed, a tree or shrub may need additional safeguards to counter the effects of strong winds, protect it from vandals or maintenance equipment, or stabilize it in sandy soils until it can support itself. Staking or guying may be used to provide those safeguards. Staking uses one, two, or three wood or metal stakes driven into the ground parallel to the trunk of a tree and down into solid, undisturbed soil. The stakes should be long enough to extend about 8 inches above their point of attachment to the tree. The point of attachment should be about 6 inches above the highest point where the trunk can be bent by a strong wind yet return to its upright position.

The stakes can be attached to the tree in several ways. The traditional way has used heavy wire looped through links of hose at the point of contact with the tree, then attached to the stakes and tightened by twisting the wire at its center until the desired tautness is attained. Although still used, the wire and hose link technique has been shown to cause injury to some plants when repeated movement by the wind causes the hose coverings to wear away the bark. That may result in a girdling condition. Currently gaining favor and acceptance are commercial ties that replace the wire and hose links. Made of tough, weather resistant webbing, the ties are flat and wider than wire, so they do not gouge the bark. They also have a slight elasticity, providing a more flexible support to the plant than the wire and hose technique. Since the webbing material cannot be twisted like wire, it should be applied with a figure-eight loop between the stake and the tree to allow for flexibility.


Using a single stake is most appropriate when the intent is to prevent a plant from being pushed off center by a strong prevailing wind. In such a case, the stake is positioned on the upwind side of the plant. For the stabilization of small trees, two stakes are often used. They are placed on opposite sides of the trunk and attached to the same point on the tree, Figure 20-6. Securing the trunk at additional levels along the stakes should be avoided because it creates additional stress points when the tree moves in the wind. However, the two stakes can be reinforced at the base with a wooden cross tie to prevent their wobbling and coming loose. On windy sites, three stakes may be used for added stability. Three stakes also offer greater protection from mower damage and may dissuade vandals.

Guying is the stabilization of large trees and multistemmed plants using the hose wrapped wires or strapping material described above, but attached to anchoring devices that are driven into the undisturbed soil. If stakes are used as the anchors, they should be driven at a 45-degree angle to the ground surface and point toward the tree. If driven to point away from the tree, they can become loosened over time, Figure 20-7. Usually three guys are needed to provide the desired stability. For exceptionally large trees, underground anchors, termed deadmen, may be used to ensure that the guys do not work loose, Figure 20-8. Support wires can be twisted to the desired tautness or turnbuckles installed to accomplish the same thing. For safety, all exposed wires should be flagged with colorful tape so that no one trips over them. Whether a plant is staked or guyed, all apparatus should be removed after one year to avoid injury and prevent girdling.

Protecting Thin-Barked Trees. Some young trees are especially susceptible to injury during the first year after transplanting if they have thin bark that can be scalded by the sun or dried out by winter winds. Still other young trees are damaged by the feeding of rabbits and rodents or the gouges of lawn mowers. Vinyl tree guards can be applied after installation to protect against those types of injury. They coil around the trunks from the base upward, Figure 20-9. To avoid girdling, the coils should be removed annually and reapplied if necessary. That way they do not impede the plant's growth.


Groundcovers and Bedding Plants

Both groundcovers and bedding plants are commonly sold in strips of plastic or pressed peat moss pots or in flats. Certain plants such as geraniums or flowering perennials may also be marketed in small clay or plastic pots. Peat pots need not be removed, but other containers must be. Remember that the rim of the peat pot must be buried in the soil to prevent the wick-drying effect.

To install these plants, the entire bed is prepared rather than individual holes. This allows the groundcovers or flowers to be planted with a hand trowel or hoe rather than a spade, Figure 20-10. The soil must provide good drainage and nutrients. It should also be as weed-free as possible at the time of planting. For large areas, a garden tiller may be used to loosen the soil and incorporate the necessary conditioners. The use of a preemergence herbicide prior to planting can reduce some of the maintenance requirements of the planting.



The spacing of groundcover plants depends upon the species and the speed of coverage desired. Naturally, closer spacing will result in more rapid coverage, but it will also increase the material and installation cost. To assure even and maximum coverage, groundcovers should be installed in a staggered planting pattern, Figure 20-11.

Due to the shallow root system of groundcovers and bedding plants, the plants can dry out easily. Prior to transplanting, each plant must be watered thoroughly. As each is set into the soil, it should be watered again. Thereafter, the new planting must be watered frequently and deeply to establish the plants successfully.


Groundcovers will benefit from mulching to reduce weeds and, most importantly, aid in preventing alternate freezing and thawing of the ground. Such ground activity can result in heaving the groundcovers to the surface where their roots are exposed to the cold and drying air. To be successful, mulch should be applied to a new groundcover planting after the ground has frozen, to prevent premature thawing.


Flowering bulbs require a rich, well-drained soil. They are planted either in flower beds and borders or as masses in the lawn. They may be gently tossed by the handful into open, turfed lawn areas to be planted wherever they land, in an irregularly spaced pattern. Bulbs are planted at differing depths and spacings, depending upon their species. Table 20-1 lists the depths and spacings of some common bulbs.

Bulbs are always set into the ground with the base oriented downward and the shoot pointed upward, Figure 20-12. Many can be installed with a bulb planter.


Other bulb-like structures, called tubers and rhizomes, are installed in mounded holes that permit the structure to be oriented horizontally and the roots directed downward, Figure 20-13. As always, the backfilling step should be done carefully to assure that no air pockets form. Water collecting around the bulbs in air pockets can promote rotting.


All plants benefit from mulching after installation. Mulching refers to the application of loose aggregate materials to the surface of a planting bed. The materials may be organic or inorganic. Examples of both types and their advantages and disadvantages are listed in Table 20-2.


The benefits of mulching a newly installed plant are that:

1. Water is retained in the soil around the root system and wilting is avoided.

2. Weed growth is discouraged.

3. The aesthetic appearance of the planting is enhanced.

4. Soil temperature fluctuation is minimized, preventing winter heaving of bulbs and groundcovers. Repeated freezing and thawing of the soil around a plant's base can also damage the bark and permit the entry of pathogens or insects.

For mulches to be effective, they must be applied 3 to 4 inches deep. A shallow layer of mulch does not reduce sunlight enough to discourage weed seed germination, retain moisture, or prevent changes in the surface temperature of the soil. If a more shallow layer of mulch is desired, weeds can still be controlled and water retained by spreading weed-barrier fabric around the plant base and adding 1 or 2 inches of mulch to weigh it down. The fabric prevents sunlight from penetrating and promoting weed growth. It also creates a physical barrier that weeds cannot grow through. This mulching technique works well on flat land but is less satisfactory for use on slopes, because rainwater tends to wash the mulch off the fabric surface. It must also be used cautiously on heavy clay soils because the fabric may cause the soil to hold too much water, drowning the new transplant.


Using Antitranspirants

Antitranspirants, also called antidesiccants, are chemicals that reduce the amount of water plants lose through transpiration. Antitranspirants are useful because excessive water loss can result in transplant shock. They normally act either to induce closing of the stomata or to cover the stomata with a water-impermeable coating. Several popular brand names are available. The antitranspirants are sprayed onto the plant before and after transplanting. Since most plant stomata are present in the greatest numbers on the lower surfaces of leaves, the underside of the canopy should receive thorough coverage.

Antitranspirants are of greatest benefit in the transplanting of deciduous trees and shrubs that are in leaf. They are also of benefit to evergreens, especially broad-leaved forms. Any evergreen will benefit from antitranspirants if it is transplanted in the fall, right before the dry winter period.

Problems of Arid Regions

The landscaper installing plants in the American Southwest encounters four distinct problems:

1. The soil quality is generally poor.

2. Irrigation is necessary throughout the year.

3. Higher altitudes can produce extremely hot daytime temperatures and very cool nights.

4. High winds dry out plants quickly and often damage them physically.

Arid soils generally fall into three categories: pure sand or gypsum, adobe, and caliche. Sand lacks both nutrient content and humus. Adobe is a heavy, clay like soil that holds moisture better than sand but needs humus to lighten it and improve its aeration. Caliche soils are highly alkaline due to excessive lime content. They have a calcareous hardpan deposit near the surface that blocks drainage, making plant growth impossible. The hardpan layer may lie right at the surface or from several inches to several feet below ground level. The deposits may occur as a granular accumulation or as an impermeable concrete-like layer.

Generally, these are the characteristics of arid soils:

* Lack humus

* Require frequent irrigation

* Are nutritionally poor; nutrients are continually leached out by the irrigation water

* Are highly alkaline (pHs of 7.5 to 8.5 and higher)

* Are low in phosphate; phosphate may be rendered unavailable by the high pH

* Lack iron or contain it in a form unavailable to plants

* Have a high soluble salt content resulting from alkaline irrigation waters and from manures and fertilizers that do not leach thoroughly

When installing plants in the Southwest, the landscaper must add organic matter to the soils to improve their structure. Organic matter improves the water retention capability of light, sandy soils and breaks up heavy adobe soils. The only way to improve the drainage of caliche soil is to break through it and remove the impermeable layer. The excavated soil can be replaced with a conditioned mix that will support healthy plant growth.

To catch and retain the water so vital yet so limited in arid regions, the planting beds should be recessed several inches below ground level to create a catch basin, Figure 20-14. This method traps and holds applied water, preventing loss through runoff. In addition, organic mulches should be applied to a depth of 4 inches to slow moisture loss and create a cooler growth environment for the roots. Trunk wraps and whitewash paint are also applied to the trunks of trees to prevent water loss through their thin bark due to sun scald.

Cactus plants are sufficiently different from other plants to warrant special mention. They can be transplanted successfully by following these steps.

1. Before transplanting, mark the north side of the cactus. Orient this side of the plant to the north in its new location. The plant will have developed a thicker layer of protective tissue on its south side to withstand the more intense sunlight.

2. By trenching around the cactus, lift as much as possible of the root system.

3. Brush soil from the roots and dust them with powdered sulfur.

4. Place the cactus in a shaded area where air circulates freely, and allow the roots to heal for a week before replanting.

5. Plant the cactus in dry, well-drained soil. Stake the plant if necessary.

6. Water the plant in three or four weeks, after new growth starts. Thereafter, apply water at monthly intervals.

Whenever possible, native or naturalized plants should be selected for Southwestern landscapes. They have a better chance of surviving the transplant, and they keep maintenance costs down. In situations where the soil is especially unsuitable for planting, there may be little choice but to install the plants above ground in planters.

Planting in the Southeast

While the plants and soils of the American Southeast are definitely different from those of the temperate zoned states, the methods of plant installation do not vary greatly. What differences do exist are related mostly to the uniqueness of certain species, most notably the palms.

Palms are like grasses, only woody-like trees and shrubs. They may have single or multiple trunks. There are many different types of palms, surviving in a range of hardiness zones and settings as diverse as the seacoast and the desert. Each branch has only a single terminal bud, allowing the plant to grow only at that point. Roots are produced continuously from the base of the trunk, and they are shorter lived than the roots of temperate zone trees and shrubs. The majority of palms that are used in landscapes are grown in nurseries, not the wild. They may be produced in containers or grown in fields. Like other trees and shrubs, palms must have an adequate root and soil ball attached if they are to transplant successfully. However, because of the difference in how and where the roots are produced, the root ball of a palm is seldom as large as that of other transplants. A root ball diameter that is about two feet greater than the diameter of the trunk is generally accepted as an adequate size. To be certain, landscapers should consult the local industry standards of their geographic region since there is no single industry norm. Large palms can be moved with a tree spade. Smaller plants are handled with ball carts or carried at the root ball. To protect the tender terminal bud, the fronds of a palm are usually tied up and around the end of each branch with biodegradable twine before being harvested and moved. It is important to keep the root ball moist until the installation is accomplished, Figures 20-15 A and B.


Palms should be set at the same depth they were in the field or in their production container. If set too shallow, they may topple over. If set too deep, they may suffer nutrient deficiency. Staking is often needed to stabilize the new transplants.


The technique used is an exterior support brace, not the devices described earlier in this chapter, Figure 20-16.

Following their installation, the palms should be kept well watered and misted throughout their first season. Where conditions are excessively hot and dry, the fronds remain tied around the terminal bud for most of the first season as well to protect it from drying. The support structure may remain in place for up to a year.


Achievement Review

A. Answer each of the following questions as briefly as possible.

1. Identify the following tools, used in the installation of landscape plants. (See Appendix B for review.)


2. List the four qualities of good backfill soil.

3. Indicate whether the following are characteristic of bare-rooted (A), balled and burlapped (B), or containerized (C) plants.

a. lightweight and easily transported

b. retain the entire root system

c. severely reduced root system

d. usually the most expensive

e. plants may become pot-bound

f. permits large plants to be transplanted

g. transplant season limited to early spring

h. allows transplanting in any season

4. What is the primary objective when deciding the timing of a plant transplant?

5. Why is early autumn the most desirable transplanting season for most plants?

6. Indicate whether the following are characteristic of inorganic (A) or organic (B) mulches, or both (C).

a. reduce water loss from the soil

b. may alter soil pH

c. may temporarily reduce nitrogen content of soil

d. hazardous if thrown by a mower blade

e. do not biodegrade

f. sometimes are slightly nutritional

7. What benefit is gained by applying antitranspirants to new transplants?

B. Indicate if the following statements are true or false.

1. The root form of a transplant determines the size and configuration of the planting pit.

2. Balled and burlapped plants are installed in a pit with a mounded bottom.

3. Butterflying is used when installing groundcovers.

4. Burlap around the soil ball should be permitted to extend above the backfill to assure proper aeration to the root system.

5. Wire baskets should be removed entirely before the root ball is set into the planting pit.

6. Where soil drainage is poor, setting the plant above grade level is recommended.

7. Landscape fabric is better suited for use around plants that have been installed as containerized stock than as balled and burlapped stock.

8. For rapid and maximum coverage, groundcovers should be installed in staggered, alternating rows.

9. Staking and guying are interchangeable terms for the same technique.

10. Backfilling a planting pit with the same soil dug from the pit is recommended over the use of soil conditioned with additives.

C. Installation of plants in the American Southwest is complicated by poor soil and the lack of adequate natural water supplies. What must a landscaper do to counter these threats to plant survival?

Suggested Activities

1. Install a tree in a nearby yard, park, or school campus. Apply the information given in this chapter. If possible, install both a deciduous and an evergreen plant. Stake or guy the trees as appropriate. NOTE: Arbor Day is a good occasion to do this activity. There may be a number of planting opportunities nearby.

2. To demonstrate the benefits of landscape fabric in weed control, fill three greenhouse flats with nonsterile soil. Cover one with a thin layer of organic mulch, one with a sheet of landscape fabric and a thin layer of mulch, and leave one without any coverage. Give all the same amount of sunlight and water over a period of several weeks. Observe the number of weeds seen in each flat.

3. To observe the effects of girdling, use a small containerized woody plant for this demonstration, which will require some time for the effects to be noticed. Using a sharp knife, carefully cut through the bark, encircling the main stem or trunk. Remove about a 1/2-inch wide strip of bark around the entire base. Be careful not to cut any deeper than is necessary to peel off the strip of bark. This duplicates the type of damage done to a plant by rodents or other means. Keep the plant watered. You may even choose to add fertilizer to the soil. Over time you should notice that the plant does not will because it can still take up water. However, the leaves will begin to show signs of discoloration and other indications that it is not receiving the nutrients from the soil because part of its vascular system has been destroyed by the girdling. Eventually the plant will starve and die.

Jack E. Ingels

State University of New York

College of Agriculture and Technology

Cobleskill, New York
Table 20-1 A Guide to Bulb Installation

Plant                  Depth to Top of Bulb   Spacing

Amaryllis              Leave upper 1/3        One bulb per pot
                         of bulb exposed
Anemones               2 inches               12 inches
Bulbous iris           2 inches               12 inches
Caladium               2-3 inches in North    As desired for effect
                         /1 inch in South
Calla lily             Leave upper 1/3 of     One bulb per pot
                         bulb exposed
Cannas                 3-4 inches             1 1/2-2 feet
Crocus                 3 inches               2-4 inches
Daffodil               4-5 inches             6-8 inches
Dahlia                 5-6 inches             2-3 feet
Elephant ears          Just below soil        As desired for effect
Gladiolus              3-4 inches             6-8 inches
Grape hyacinths        3 inches               2-4 inches
Hyacinths              4-6 inches depending   6-8 inches
                         on size
Lilies                 Two to three times     1 foot
                         the thickness
                         of bulb
Paperwhite narcissus   Just below soil        One or two bulbs
                         surface                per pot
Ranunculus             2 inches               12 inches
Snowdrops              3 inches               2-4 inches
Summer hyacinths       4 inches               6-8 inches
Tuberous begonia       Just below soil        6-8 inches
Tulips                 4-5 inches             6-8 inches

Table 20-2 Characteristics of Common Mulches

         Organic Mulches                    Inorganic Mulches
(peat moss, wood chips, shredded      (marble chips, crushed stone,
  bark, chipped corncobs, pine        brick chips, shredded tires)

* reduce soil moisture loss         * reduce soil moisture loss
* often contribute slightly         * do not improve soil nutrition
  to soil nutrition                 * seldom alter soil pH
* may alter soil pH                 * are a hazard if thrown by a
* are not a mowing hazard if          mower blade
  kicked into the lawn              * are nonflammable or
* may be flammable when too dry       fire-resistant
* may temporarily reduce nitrogen   * have no effect upon nitrogen
  content of soil                     content of soil
* require replacement due to        * do not biodegrade
  biodegradation                    * may retain excessive amounts
* may support weed growth as they     of solar heat

Figure 20-2 Root forms of landscape plants

Root Form       Advantages               Disadvantages

[ILLUSTRATION   * Comparatively          * Severely reduced
OMITTED]          inexpensive              root system
                * Lightweight and easy   * Transplant season
                  to transport             limited to early
                * Dormant at the time      spring
                  of planting            * Usually small,
                                           requiring time
                                           to mature

[ILLUSTRATION   * Larger material can    * Usually the most
OMITTED]          be transplanted          expensive
                * Less damage to the     * Soil ball adds
                  root system              weight and bulk
                * Can be transplanted    * For large plants,
                  throughout spring        costly installation
                  and fall                 equipment is

[ILLUSTRATION   * Less expensive than    * Seldom available in
OMITTED]          B & B material           large sizes
                * Root system intact     * Can become
                * Can be transplanted      root-bound if kept
                  throughout spring,       in containers too
                  summer, and fall         long
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Title Annotation:SECTION 2 Landscape Contracting
Author:Ingels, Jack E.
Publication:Landscaping Principles and Practices, 6th ed.
Date:Jan 1, 2004
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