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Tomatoes 2008
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Well-chosen plantings are necessary to achieve the desired landscape effect. There are hundreds of varieties of trees, shrubs, vines and perennials from which to choose. Remember, plants are not merely ornamental accessories; they make up masses and define space in the yard and garden. Therefore, when selecting plants, consider both their cultural needs and aesthetic values. Cultural Considerations in Selecting Plants. Several cultural issues need to be considered when selecting plants. Hardiness. This is the plant’s ability to withstand winter and summer climatic changes. It also refers to plant longevity or permanence. Usually, a fast-growing plant has a short life span and consequently needs replacing after a few years. Soil and moisture conditions. These are important parts of the plant’s environment. Some plants respond unfavorably to changes in soil or moisture. For example, some plants can tolerate extremely dry or wet conditions while others cannot. Degree of sun or shade. This depends on where the plant is located in the garden. Some plants cannot tolerate the sun, while others require full sun for best display. Maintenance. When selecting plant materials, consider the more practical aspect of maintenance. Try to choose trees and shrubs that tend to be disease and insect resistant. Aesthetic value. This includes texture, color or foliage, flower, fruit and bark. Select colors related to the house exterior, especially if the plant is used close to the house. Strongly contrasting textures can create interesting effects. Aesthetic Considerations in Selecting Plants. In addition to cultural considerations, aesthetics are a vital portion of the plant selection process. Plant size. The mature size of a plant must be considered when selections are made for the landscape plan. A common mistake is to select plants which become too large for their location. The drastic pruning which then becomes necessary adds to the cost of maintenance and may reduce the grace and beauty of the specimen. Overgrown plants which are left unpruned will alter the balance and accent of the design, and may partially hide the house which they are supposed to complement. The landscape picture is constantly changing because the plants which give it form and substance are continually growing. This presents the landscape architect with a challenge not found in most other artistic media. Great care must be exercised in selecting plants that will immediately create the desired composition and yet retain an appropriate size over many years. Plant form. Trees and shrubs used in landscaping develop many distinct forms. The more common forms are prostrate or spreading, round or oval, vase, pyramidal and columnar. Mature shrubs and trees are usually more open and spreading than young plants. For example, the head of a young oak tree may be pyramidal in shape. During middle age, the head is an irregular oval, while during old age, a large, massive oak may have a spreading vase form. Groundcovers, such as turf, low-spreading shrubs, creeping plants and prostrate vines, are essential materials in landscaping. The principal use of turf is for the lawn area. Other ground-cover plants are commonly used on banks which are too rough or steep to mow or under trees where grass will not grow well. Shrubs are woody plants which reach heights, up to 15 feet. They may have one or several stems with foliage extending nearly to the ground. The more common shrub forms include low-spreading (juniper species); round or upright (a large majority of shrubs fall into this general form); vase (Spiraea X Vanhouttei); pyramidal (Arborvitae spp.); and columnar (Juniperus spp.). Trees are woody plants which typically grow more than 15 feet tall and commonly have one main stem or trunk. The head or leafy portion of the tree develops a typical form. Examples include round or oval (most common trees such as sycamore, oak and pine); vase (elm); pendulous or weeping (willow, cherry ); pyramidal (spruce, fir ); and columnar (Lombardy poplar, Italian Cypress). Trees are long-lived and relatively inexpensive in initial cost and maintenance compared to lawns, flower beds and many other features of the design. In the past, many builders have committed costly errors by destroying trees when establishing new residential subdivisions. Most real estate developers now appreciate the value of trees and try to save them when land is graded prior to the construction of houses. Regardless of our affection for trees, we must recognize that they do not live forever. Old and improperly located trees should be removed and new, more suitable specimens should be planted. Plant texture. The texture of plant materials depends on the size and disposition of the foliage. Plants with large leaves which are widely spaced have coarse texture. A plant with small, closely-spaced leaves has fine texture. Extremes in texture which prevent harmony in the composition should be avoided. On the other hand, some variation in texture is needed to give variety. Texture can be influenced on a seasonal basis, depending on whether the plant is deciduous or evergreen. Plant color. Green is the basic color of most plant materials in the landscape picture. Variety may be secured by using plants with lighter or darker foliage tones. Accent may be introduced by the selection of flowering shrubs or those which produce colorful, persistent fruit. Care should be exercised in the use of particularly showy plants, such as hydrangeas or blue spruce. Such plants may dominate the landscape and destroy the balance and unity of the composition. Woody Landscape Plants Woody ornamental plants are key components in a well designed, useful landscape. This large group of plants falls into four categories: vines, groundcovers, shrubs and trees. These categories are defined as follows: Vines — Climbing or crawling woody plants without self-supporting upright stems. Groundcovers — Very low growing, spreading vines and shrubs. Shrubs — Woody plants that remain quite low and produce shoots or stems from the base with usually more than a single trunk (height of 15 feet or less). Trees — Woody plants that produce one main trunk and a more or less distinct and elevated head (height of 15 feet or more).. Vines Vines offer diverse visual qualities and are valued for the rich texture of their foliage and their decorative growth habit. They are also desired for the fragrance of their blooms or the beauty of their flowers. Some are valued for the graceful tracery of their simple stems or for the beauty of their leaf pattern. To the landscape professional, vines offer a rich source of material with which to create interesting, exciting and beautiful plantings. Depending on how they climb, vines are usually segregated into three general groups. Some vines, like Boston ivy, climb by attaching small, rootlike holdfasts to the wall as a means of support. These may be modified tendrils with small circular discs at the tips. Others vines, like English ivy, have small rootlets along the stem which firmly attach to either brick or wood. The second group of vines, such as clematis and grape, climb by attaching and winding tendrils, or leaf like appendages which act as tendrils, around the object on which they are growing. The third group of vines, including bittersweet and wisteria, climb by twining. It is interesting to note that different vines twine in different directions. As an example, bittersweet vines twine by climbing from left to right, while Hall’s honeysuckle twines by climbing from right to left. By knowing in advance how each vine climbs, the proper means of support can be selected. It should also be noted that the climbing action of many vines can be quite damaging to wooden structures, such as fences or arbors. Make sure any such structures are designed to withstand the vigorous growth of most vines. Culture. Most vines quickly revert to a tangled mass of foliage on the ground if they are not given the proper means of support and a reasonable amount of care and maintenance. The best type of support for vines is one that gives the required structural strength and stability, and at the same time has a neat appearance. Beware that holdfasts and rootlets, such as those on English ivy, can damage wood siding on a house. Like most other plants, vines require some maintenance. Pruning is necessary to remove old wood and may require several cuts to each stem so they can be untangled. Pruning is occasionally necessary to keep the plant within bounds and to guide future growth. As with other plants, vines can also be pruned to produce better bloom. Management of insect and disease pests is required for vines. This involves regular visual inspection for pest damage and, if necessary, use of environmentally-sound control measures. Carefully study the area to determine what type of vine to use. Growth rate is a critical consideration since some vines exhibit rampant growth such as grapes and trumpet vine, and they can soon become a nuisance. Groundcovers In a broad sense, groundcovers include any material that prevents rain from directly striking the ground as well as covers the ground surface so that it cannot be seen from above. Under this definition, grass, various types of paving, shrubs and even trees could be called groundcovers. In this handbook, however, groundcovers refer to low, mat-forming or trailing plants (up to 18 inches tall) other than turf grasses or plants that tolerate walking or mowing. Most groundcovers are not intended to be walked upon and may be severely damaged by pedestrian traffic. When groundcovers are carefully chosen and correctly placed, they greatly enhance the beauty of the landscape composition. In addition to their aesthetic value, they fulfill a number of other important functions include the following:
Selection. Groundcover selection depends upon the area where it will be used. When selecting a groundcover, consider the following questions. Is the area flat or sloping? Is it in sun, partially-shaded or deeply-shaded? Study soil conditions; some groundcovers prefer a moist soil rich in organic matter, while others adapt to dry, sandy situations. Consider color, texture, height and growth habit as well, since some groundcovers tend to grow rampantly and may become nuisances. Since large numbers of small, individual plants are required, one problem that may limit the use of groundcovers is the cost of installation. A well-prepared planting bed is essential to the establishment of groundcovers, but it can also be costly and time-consuming. Weed control in a newly-planted groundcover bed can likewise be difficult and labor-intensive. Culture. Significant maintenance is necessary the first 1 to 3 years or until the groundcover becomes established. This includes cultivation to control weeds and other plant invaders; fertilization to encourage fast, vigorous growth and to achieve good cover; irrigation in times of dryness; and disease and pest management. If these maintenance considerations are ignored, the resulting groundcover planting is disappointing. Groundcovers can be successfully used wherever paving, lawn or flower beds are not desired. Newly-cut banks and any slopes greater than 12 percent are best treated with groundcover plantings. Around buildings, groundcovers are superior to paving or structural controls for reducing heat, glare, noise and dust. Refer to the planting lists for groundcovers to fit any landscape need. Trees and Shrubs Because there are so many woody plants available for use in landscaping, carefully consider plants that are appropriate for your needs. Selecting Trees and Shrubs. Selection should be based on several different factors. The intended purpose should influence the selection of plants for appropriate shape, size and other physical characteristics. Trees are used for shade, ornamentation, screening and windbreaks. Shrubs are used for screens, barriers, windbreaks, ornamentation, groundcovers and wildlife shelters. Both trees and shrubs can be selected for their edible fruits or nuts. Providing shade usually requires tall, sturdy, long-living species. Density of foliage determines the amount of shading. A tree that produces very dense shade, such as a mulberry, may prevent other plants from growing beneath it. Other trees, such as a honey locust, produce light or partial shade which does not hinder the growth of other plants below it. Deciduous trees which drop their leaves in winter can be used to shade the southern windows of a home during summer, and thus allow sunlight to penetrate the same windows in winter. Screens usually require plants that produce dense foliage. Evergreen plants are usually chosen for screening. In addition, plants used for windbreaks must be able to survive rigorous climatic conditions. Barrier plantings usually require sturdy plants with dense growth and possibly with thorns or spines. Ornamental attributes are quite varied. Both trees and shrubs can be selected for their colorful flowers or fruit, interesting foliage, fall color, interesting bark, winter foliage or branches for decoration, as well as for the interesting shapes of the plants themselves. Consider the size of mature trees and shrubs and where they are to be used. Tall trees, such as live oak, cedar elm, sycamore and magnolia, are suitable for 2-story and taller buildings. They tend to dominate or hide low, flat, 1-story buildings. For attractive and proper balance with 1-story buildings, select trees that reach maximum heights of about 35 feet (see plant listings). Shrubs that outgrow their spaces can hide windows, block walkways or crowd out other plants. Shrubs can sometimes be kept small by pruning, but this requires continuous maintenance. Careful consideration of mature size reduces the need for pruning. Shape is especially important in selecting trees for ornamental and shade purposes. Tall trees with long, spreading or weeping branches give abundant shade. Small trees and trees of other shapes are useful for ornamental purposes, but they may not give abundant shade. Environmental conditions should influence the selection of plants. Size of the planting area is important, as are other site characteristics, such as full sun or shaded, wet or dry and exposure to winter winds or pollution. Selected plants should be tolerant of existing conditions and should be hardy in the appropriate climate zone. The United States is defined in a series of zones based on average minimum winter temperatures; these zones are illustrated in the USDA Hardiness Zone Map. Remember that a “hardiness zone map” does not reflect information concerning soil type, summer heat or average rainfall within each zone. It should only be used as a guideline to determine if a plant species can withstand the average minimum winter temperatures of a specific zone. While this map contains the most recently published information, the guidelines may not be accurate enough to guarantee plant survival in extreme cold. Finally, consider how much maintenance the plant requires and any possible disadvantages associated with the species, including susceptibility to diseases and insect pests; soft or brittle wood that is easily damaged by wind and ice; fruits and seeds that are large, messy, smelly or otherwise obnoxious; and plants that abundantly shed twigs and small branches. Some examples of these conditions are the slow death of Arizona ash from age and borers, the breaking of Siberian elm branches by wind and ice and the production of foul-smelling fruit by the female ginkgo. Fruit production by the mulberry, which attracts birds, can also be undesirable. Since the fruit is soft, dark, and decomposes rapidly when ripe, it is messy on walks and attracts flies and other insects for this reason choose fruitless varieties which are male, thus produces pollen for many people. Flowering tree pollen is not as allergenic. In many cities the fruitless mulberry is banned. Check local ordinances. Purchasing Trees and Shrubs. Once all selection criteria have been considered, it is time to purchase plants. Transplants are grouped into the following three classes according to the way they are dug and/or shipped: bare-root plants, balled-and-burlapped plants (B&B), and container-grown plants. Bare-root plants. These plants have had the soil washed or shaken from their roots after digging. Plants handled this way are nearly always deciduous trees or shrubs in their dormant stage. Most mail order plants are of this class because plants in soil are too heavy to ship economically. Plants in the bare-root class are planted while they are dormant; therefore, winter planting is best for these plants. Never let the roots dry out; this is perhaps the single, most common cause of failure with bare-root plants. Keep roots in moist sawdust or wrapped in plastic or wet paper until you are ready to place the plant in the hole. Balled-and-burlapped plants. B&B plants are primarily trees and some shrubs. They are usually grown in nursery rows for some time and are root-pruned so that the root system within the balls is compact and fibrous. Such plants rapidly reestablish themselves. This method is primarily used for plants that never lose their foliage and thus are not amenable to bare-root treatment. B&B plants include broadleaf evergreens and conifers of all types. A number of deciduous trees and shrubs that have branching root systems are easily contained in a soil ball and are also sold as balled-and-burlapped plants. Plants in this class are planted almost any time the ground can be worked. Plants put out in summer will need special attention to keep them adequately watered. When selecting a B&B plant, be sure that the ball is sound and has not been broken. Avoid plants that feel loose in the soil balls. Be sure the soil ball does not dry out. These plants will usually need very little pruning at planting. Container-grown plants. These plants are usually grown in the container in which they are sold and are becoming a standard in the nursery trade. Container-grown plants can be planted throughout the year. Because of their appearance, many home gardeners are often misled into thinking that all they have to do is put these plants into the ground and forget about them. Nothing could be further from the truth. These plants may have what is called a “container habit.” Their roots are contained in a limited space and may be tightly coiled around one another in the container. Some of the larger roots may have coiled back around the trunk, thus initiating a process known as root strangulation or girdling root. To solve the container habit, split the lower half of the root system and horizontally spread the roots. This practice prunes the roots, thus encouraging new laterals, prevents girdling roots and raises the lower roots closer to the soil surface. When selecting plants, look for those with a good, natural shape without any thin spots or broken limbs. Make sure the root ball is solid and the bark has no broken places. Avoid container-grown plants if the roots are circling on the surface or coming out of drainage holes. Choose plants that are free of any insects or diseases. Generally, smaller plants cost less and may establish faster. Do not buy plants so small that they are in danger of being walked on or mowed over. Planting Trees and Shrubs. Proper installation of plants in the landscape involves much more than just digging holes and setting plants in them. The planter is responsible for developing as satisfactory a microclimate as possible for optimum plant growth and development. A healthy and vigorous plant is required if the landscape is to have the desired effect, and healthy plants need less maintenance in the years following establishment. The planting hole is important since this is the environment of the root system. Plantsmen make many suggestions about how large the planting hole should be, but generally if the hole is twice as wide in diameter and no deeper than the soil ball, the size is adequate. In general, research shows that the wider the hole is, the better the plant will grow. A traditional recommendation for preparing planting holes for trees and shrubs has been to incorporate organic matter into the backfill soil before returning it to the hole around the plants. However, recent research indicates that this can actually be detrimental to the long-term establishment of the landscape plant. By backfilling the hole with native soil, the plant is immediately forced to establish new roots in the backfill and beyond. Apparently, the addition of organic matter into backfill soil creates an interface between the amended soil and the undisturbed soil around the planting hole that is detrimental to root growth and water movement between the two soils. In tests conducted at the University of Georgia, examination of plant root systems in holes with amended soil revealed that the majority of the roots were confined to the original planting hole. Therefore, it is recommended to use only excavated soil as backfill. Place the top of the soil ball at a slightly higher level than the surrounding soil. The finished planting depth (after the soil settles) should be such that the plant is exactly the same depth after replanting as it was when grown in the nursery (Figure 7.18). When planting in a poorly drained site, set the plant so that a few inches of the root ball are above the soil level to enhance drainage (Figure 7.19). More plants are probably lost because they were planted too deeply than for any other reason. This is especially true with large, balled-and-burlapped trees and shrubs, such as yaupon holly, which are often top-heavy and planted deeply so that they will not fall over. Carefully handle B&B plants when they are placed in the hole. On most species, if the soil ball is broken for any reason, many of the roots will be severed from the trunk and the plant will die. Always pick the plant up by the soil ball or container, but never by the trunk or stem. Recently, some nurseries have been using woven plastic or synthetic materials to wrap B&B plants. These materials do not rapidly decompose and can girdle roots as they enlarge after passing through the material. It is necessary to remove burlap from the soil ball of B&B and always remove plastic and synthetic materials after the plant is placed in the hole and before backfill is placed around the root ball. On all B&B plants, cut and remove any strings (plastic or natural fiber) from around the trunk after planting to prevent girdling the plant. For container-grown plants, always remove plastic or metal containers before planting. Small containers with tapered sides can be removed by turning the plant upside down and giving the top edge of the container a sharp rap. Catch the soil ball in the hands as it slips from the container. Do not let the soil ball break apart. Larger containers (5 gallons or more) should be cut away with special cutters. If plants have become overgrown in the container and the root mass is growing in a tight, compact circle around the soil ball, cut the outer roots out with a sharp knife in two or four places around the soil ball. Make the cut from the top to the bottom of the soil ball. Decomposable containers, such as papier mâché, do not need to be removed from the soil ball. Bare-root plants should have the packing material and all damaged or dead roots removed. Do not allow roots to be exposed to sunlight or to dry out before planting. It is best to keep bare roots covered with moist burlap or some reasonable substitute until planting time. After the B&B plant or container-grown plant has been placed in the hole, fill the hole around the plant with backfill until it is two-thirds full. With bare-root plants, the soil should be worked gently in and around the roots while the plant is being supported. The most satisfactory way to firm the soil and remove air pockets is by filling the hole with water. If it is not practical to use water, firm the soil by hand around the plant ball or roots. However, be sure not to use excessive force since soil compaction should be avoided. Before finishing the filling process, make certain the plant is straight and at the proper depth; then, complete the filling process with backfill. If it is an individual specimen, construct a ring of backfill 2 to 3 inches high at the outer edge of the diameter of the hole to form a water basin (Figure 7.20). Bedded plants will probably not require a water basin. Thoroughly water the plant as soon as the water basin is complete. After the water has soaked away, fill the basin with mulch. Organic mulches, such as pine needles, bark and wood chips, provide the best environment for future root development. Note that fertilizer is not added to the backfill mixture. Newly developing roots can be damaged by too much fertilizer. If soil testing indicates that fertilizer is needed, add a water-soluble material at the recommended rate during the final watering phase. Large areas should already have an established fertility level based on soil test results before individual plant specimens are planted. A fertility program should begin in late fall of the first growing season. One final activity in planting any plant is to remove all tags and strings. These items, whether made of wire, plastic or natural fibers, can potentially girdle fast-growing stems and trunks. Pruning and Supporting Newly-Installed Plants. An initial pruning may be needed immediately after planting; however, this pruning should be directed only at the removal of all broken and damaged branches (Figure 7.21). The traditional practice of removing part of the top growth to reduce transpiration and to make bring the top back in proportion to the root system (for example, bare-root trees) is no longer recommended. With newly-planted woody species, it is usually more successful to avoid heavy pruning at planting if the plants can be well-watered during their first 1 or 2 years. Pruning reduces leaf area and thus limits transpiration, but it also reduces the leaf surface area which produces photosynthates for root growth. Since the plant will not resume a normal growth rate until the original root system size is reestablished, it is better to avoid wilting by watering than by canopy pruning. This also avoids a proliferation of suckers in the inner canopy. Most shrubs do not need to be supported after planting unless the bare-root stock is quite large or if very tall B&B specimens are used. If support is needed, use the same techniques for shrubs that are described in the following paragraphs for trees. A general rule of thumb is to provide support for all bare-root trees over 8 feet in height. Also, trees that are quite large, 6 inches or more in diameter, should be supported. Smaller B&B or container-grown trees do not usually need support. There are several methods for supporting smaller trees (Figure 7.22). A single stake about three-quarters the height of the bare-root tree should be driven 2 to 4 inches from the center of the planting hole so that the stake will be on the southwest side of the tree trunk. This should be done before the tree is placed in the hole. Then plant the tree according to the procedures described in previous paragraphs. After planting is completed, fasten the tree to the stake with a wire or a suitable substitute formed in a loose loop. Before fixing both ends of the wire to the stake, slip a short length of rubber hose onto the wire. The part of the wire in contact with the trunk should be covered with the rubber hose to prevent injury to the bark as the tree moves in the wind. The advantage of this method of support is that the stake is close to the trunk and does not cause maintenance problems. In turf areas, stakes and guy wires outside the perimeter of the planting hole can be troublesome since they hinder mowing operations. Under no circumstances should this method of support be used on B&B or container-grown stock, because it is usually not possible to locate a stake close to the trunks of such stock before planting, and if driven through the soil ball, the stake will damage the soil ball and the roots. A more satisfactory method of supporting small trees is to use two parallel stakes driven at least 18 inches into firm soil on opposite sides of the tree about a foot beyond the planting hole. The height of the stakes after being driven into the ground should be approximately two-thirds the height of the tree. The tree is then supported by wires attached to both stakes and looped loosely around the trunk. A length of rubber hose can be used to protect the tree trunk. A third and most commonly used method, is to fasten three guy wires to stakes that have been firmly fixed in soil around the edge of the planting hole. The stakes should be equidistant from the hole and from each other. Stakes are generally used on smaller plants. They should be driven 18 to 24 inches into the ground at a 45° angle away from the tree trunk. It is absolutely essential that all three stakes be firmly fixed so that they will not pull out in high winds. The top of the stakes are notched to hold the wire. The wire is then fastened two-thirds of the way up the trunk by a loose loop covered with rubber hose. The other ends of all wires should be fastened equally tightly to the stakes without putting a strain on the trunk. The wires should be firm but loose enough to allow slight movement of the tree, a factor essential to its proper development. All support should be removed from the small trees within 1 year after planting. The tree should have become established within this period of time. It has been reported that growth and trunk strength are actually reduced if the supports are left in place for longer periods. Landscape plants require periodic maintenance to produce the best results. This includes fertilization, winterizing, mulching, watering and pruning. Fertilizing Trees and Shrubs. Ornamental trees and shrubs planted in fertile, well-drained soil or in a regularly fertilized lawn should not require annual fertilization. Trees and shrubs that are growing well don’t require extra nutrients. If trees and shrubs are growing poorly, fertilization may be helpful. Plants which are growing poorly may exhibit any or all of the following symptoms:
The cause of poor growth may or may not be evident. Transplanted ornamentals or those whose roots have been disturbed by construction within the past 5 or 10 years may be in shock. Traditionally, pruning has been recommended to bring the top growth into balance with the reduced root system; however, recent research indicates that such pruning may be detrimental. Efforts should be concentrated on maintaining the existing foliage which produces the necessary photosynthates to regenerate injured roots. Irrigation, aeration and fertilization are all recommended to keep leaves on the tree. Most trees and shrubs tolerate a rather wide range of soil acidity. They will usually make satisfactory growth without special treatment to raise or lower soil pH. However, some plants are exceptions to the above rule, such as azalea, blueberry, camellia, laurel and rhododendron. These plants grow best on acid soil with a pH of 5.0 to 5.5. These acid-loving plants may become quite yellow and grow poorly on soils with a pH of 6.0 or higher. Lowering the pH to these levels is very difficult and requires constant monitoring. Fertilizer for small trees and shrubs should be based on soil analysis. Spread fertilizer evenly under their branches in late winter or early spring. As with turf grasses, fall fertilization has been shown to be beneficial to plants that grow poorly but it should be applied early enough so trees become fully dormant before hard freezing temperatures occur. Large trees that need fertilization require large doses of nitrogen. Research indicates that complete fertilizers are usually not essential and that the growth response is primarily associated with nitrogen fertilization. On large trees, fertilizer applications should be concentrated at the dripline of the tree or beyond, which is the area directly below the outermost tips of the branches. The feeding root system of the tree is in this large perimeter and, consequently, is where fertilizer and water should be applied. Placing fertilizer in small holes in the soil has been tested and research now indicates that surface application of fertilizer is sufficient. Depending on the reason a large tree is doing poorly, fertilization might be needed each year. However, a feeding program must be combined with proper cultural practices. For example, neglecting necessary insect or disease control and failure to remove dead wood from a large shade tree will negate the positive effects of fertilization. Fertilizer is not a substitute for water during drought. A moderate growth rate and good green color are all that is desired of woody plants. Excessive vigor, evidenced by lush green leaves and long shoot growth, is undesirable. Such plants require more maintenance, are more susceptible to winter cold injury and are more likely to be broken during wind or sleet storms. These plants also will usually have a shorter life than woody plants with moderate growth rates. Mulching Plants. For year round benefits, apply a 2-inch mulch of compost, shredded bark or wood chips around shrubs, roses and recently planted trees. This mulch will conserve moisture, help suppress the growth of weeds and grass and moderate soil temperatures. A 2-inch layer should be used under the branches of shrubs and roses of all ages. A circular area of mulch should be maintained for at least 3 or 4 years around newly-planted ornamental trees. It should extend at least 3 feet from the trunk and be renewed as often as necessary to maintain a layer 2 inches thick. A circle of mulch will make it easier to mow around young trees without damaging the bark. Both organic and inorganic mulches can be useful in the landscape. Some of the more readily available and more commonly used mulches include sawdust, compost, pine needles, rock, gravel and woven plastics. Watering the Landscape. Of the tremendous amounts of water applied to lawns and landscape, much of it is never absorbed by the plants and put to use. Some water is lost to runoff by being applied too rapidly, and some water evaporates from exposed, unmulched soil. But the greatest waste of water is applying too much too often. By simply using effective and efficient watering methods, irrigation requirements can be cut by 10 to 30 percent, plus landscape beauty and quality can be increased dramatically. Correct watering of plants is vital for developing and maintaining a landscape planting. Lack of water can cause a plant to wilt and ultimately dry up and die. Excessive water can cause root rot; the plant wilts because it is oxygen-starved and, consequently, is unable to absorb moisture. As a rule, plants are capable of withstanding moderate drought more easily than too much moisture. For this reason, it is important to water thoroughly, yet allow the soil to become fairly dry between waterings. Wilting is a condition brought about in plants when roots are unable to supply sufficient moisture to the stems and leaves. Wilting for short periods will not harm plants; however, over a prolonged period it will cause permanent damage. Sometimes a plant will wilt on a hot day because moisture is evaporating from the leaves faster than the roots can supply it. If there is ample soil moisture, the plant will absorb water in the evening to firm up the stems and leaves. However, when the leaves remain wilted the following morning, watering is recommended. It is difficult to make broad recommendations about when to irrigate due to tremendous variations in climatic conditions. However, when there is an extended period without rain during summer, newly-planted trees and shrubs should be deeply watered once a week. By allowing the soil surface to dry out somewhat between waterings, major root development is encouraged at greater depths where soil moisture is highest. Plants watered frequently but lightly are more apt to proliferate roots close to the surface, making them more vulnerable to wilting. This happens with automatic overhead sprinkler systems that are designed only to moisten the surface and run for a short period of time each night. Remember that environmental conditions are the primary factor affecting plant water needs. During cool seasons, less watering is necessary because evaporation from the leaves and soil is slow. Water use under clear blue skies can be twice as high as use under cloudy conditions. The best time to water is in the morning or evening when air temperatures are lower than they are at midday. In the evening, wet foliage can encourage fungus or mildew, making plants unsightly and jeopardizing their health. Be prepared to control diseases if you irrigate at night. Lawns. Most lawns receive twice as much water as they require for a healthy appearance. The key to watering lawns is to apply the water infrequently, yet thoroughly. This creates a deep, well-rooted lawn that efficiently uses water stored in the soil. To know when to water the lawn, simply observe the grass. Wilting and discoloration are signs of water stress. At the first sign of wilting, you have 24 to 48 hours to water before serious injury occurs. Apply 1 inch of water to the lawn as rapidly as possible without runoff. Watering only when needed and watering thoroughly produces a deep-rooted lawn which is more water efficient and drought enduring. Trees and Shrubs. All trees and shrubs need more frequent watering from planting time until becoming well rooted, which may take two growing seasons. Once established, water-efficient plants can then be weaned to tolerate less frequent watering. Proper weaning develops deep roots and makes the plants more drought enduring. As with lawns, water established trees, shrubs and groundcovers infrequently, yet thoroughly. In the absence of rain, most trees and shrubs benefit from a once-a-month thorough watering during the growing season. Remember, normal lawn watering is not necessarily a substitute for thorough tree and shrub watering. The feeding root system of a tree or shrub is located within the top 12 to 18 inches of the soil and at the “dripline” of the plant. The dripline is the area directly below the outermost reaches of the branches. Apply water and fertilizer just inside and a little beyond the dripline, not at the trunk. An effective way to water trees and large shrubs is to simply lay a slowly running hose on the ground at the dripline. Move the hose around the dripline as each area becomes saturated to a depth of 8 to 10 inches. For large trees, this watering technique may take several hours. Learn the cultural requirements of plants being grown. Different plants have different water needs; good reference books should provide information on various water requirements. For example, azaleas require more moisture than cacti. It is particularly important to irrigate evergreen plants during winter. Evergreen leaves continue to lose water during winter, especially when the temperature is above 40°F. If the soil is dry, the plants may become desiccated, turn brown and die. Therefore, water shrubs several times during winter if soil moisture is low. Irrigation Systems. The goal of any irrigation system is to supplement natural rainfall in order to give plants a sufficient amount of water without waste. By zoning an irrigation system, grass areas can be watered separately and more frequently than groundcovers, shrubs and trees. Both sprinkler and drip irrigation can be incorporated to achieve water conservation in the landscape. Sprinkler Irrigation. Sprinkler irrigation is the most commonly used method
of landscape watering. The two most common types of sprinkler irrigation systems
are the hose-end sprinkler and the permanent underground systems. Even though a
permanent sprinkler system is more water efficient than a hose-end sprinkler,
both systems require little maintenance and apply large volumes of water in a
short time. Drip Irrigation. In the future, drip irrigation may become the most common and efficient way to water a landscape. Presently, drip irrigation is not as widely used as a sprinkler irrigation. Fear of the “unknown” is probably the biggest reason drip is not used more often. New equipment, which is more user friendly, has been developed in recent years. In fact, watering lawns with subsurface drip irrigation is being more widely accepted and used in home and commercial landscapes and sports turf. Drip irrigation slowly applies water to soil. The water flows under low pressure through emitters, bubblers or micro-spray heads placed at each plant. Or, the emitters are fastened inside a hose (called tubing) by the manufacturer. The goal is to water the entire root zone of a plant or bed of plants, instead of watering individual plants. These products are called tape-type drip or in-line drip tubing. Regardless of the type of drip products used, water applied by drip irrigation has little chance of waste through evaporation or runoff. Seeking professional irrigation advice and experimenting with available drip irrigation products in small sections of the landscape are the best ways to become familiar with the many benefits of this watering technique. Mowers and Flexible-Line Trimmers. Injury and infection started by wounds from lawn mowers and flexible-line trimmers can often be the most serious threat to tree health on golf courses, parks and landscapes. Most arborists and tree pathologists have been aware of this problem for some time. Extensive research has been conducted on the importance of caring for tree wounds. This research has led to significant adjustments in pruning, cabling, bracing, injection and cavity treatment. Lawn mowers cause the most severe injury during periods when tree bark is “slipping” in early spring during leaf emergence and in early fall during leaf drop. If the bark slips, a large wound is produced even when the injury was minor. Most tree injuries occur when a power mower is used to trim close to tree trunks. This can be avoided by removing turf around trees or by hand trimming. Care must also be used to avoid harming trees with flexible-line trimmers. They can do a great deal of damage to the bark, particularly on young trees. Injury usually occurs at the root buttress since it flares out from the trunk and gets in the path of the mower. However, injury is also common anywhere from the roots to 1 foot above ground. Although large wounds are most serious, repeated small wounds can also add up to create problems. While the wound itself is serious enough, the wounded tree must also protect itself from pathogens that invade the wound. These microorganisms often attack the injured bark and invade adjacent healthy tissue, greatly enlarging the affected area. Trees can be completely girdled from microbial attack following lawn mower wounds. Decay fungi also become active on the wound surface and often result in structural deterioration of the woody tissues beneath the wound. Many wounded trees which are not girdled may eventually break off at the stem or root collar because of internal decay.
02/01/2009 |