Planting Design Guidelines

Rather, plant masses should be composed of subgroups of numerous plants of the same species, as seen on the right side of Figure 11—56 (also see Fig­ure 9—11). ЇЬГсЛПІaЬ £
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Perennials and annuals give the landscape seasonal interest. Furthermore, a variety of plant types tends to replicate conditions similar to natural plant habitats where an interrelated combination of plants typi­cally exists. Contrasting foliage texture establishes visual interest and helps one plant type read against another, as suggested in Figure 11—75. The background is often composed of tall perennials, tall shrubs, and/or trees. Figure 11-63
Example of rows and geometric blocks of plants. One of the most critical ecological factors is sun exposure. Most designs organize plants in each of these layers to provide the maximum visual interest in the vertical cone of vision and to create the strongest feeling of outdoor space. In some
Figure 11-67
Drifts of plants are appropriately used in curvilinear and naturalistic designs. Perennials are most commonly placed as foregrounds to woody plants, though they can also be used as background in their own right. • Some plants that normally grow in a more southerly hardiness zone may be located here because this area has the warmest temperatures in early spring and late autumn, thus extending the growing season. They are best used as foreground plants in the same locations defined for perennials. Coarse-textured plants are best used as visual accents because they readily stand out among other plants. They should be used in the landscape to create the primary structure of the planting design because they are typically the largest and the most enduring plants. Use Plants in Masses Perhaps the most fundamental guideline of planting design is that plants should form a continuous mass when they reach their mature size (Fig­ures 9—10 and 11—55). • Caution should be exercised for plants that cannot tolerate cold wind expo­sure if the house is located in an unprotected spot in relation to north and northwest wind. Such a map can guide the selection of plants to fit the various soil moisture conditions. A successful planting design is one that considers all seasons and creates a landscape that is equally as attractive in December as it is in June. Another use of deciduous plants is as foreground or middle-ground plants in a planting bed, especially when the background is evergreen or structural in nature. This is the most important layer in terms of creating en­closure around outdoor rooms, as well as controlling views into, through, and from outdoor spaces. This approach to planting design is most appropriate to geometric design layouts. This is especially needed in those climatic zones where deciduous plants lose their foliage in the winter. Figure 11-76
Coarse-textured plants visually "move" toward the viewer, whereas fine-textured plants recede. Figure 11-75
Contrasting plant textures based on foliage size and shape can provide visual appeal in a planting composition. As discussed in Chapter 3, a house creates four general microclimates around its exterior based on sun and wind exposure (see Figure 3—1). Furthermore, it is desirable to mass plants so they form groups of multiple plants of the same species. Figure 11-62
The presence of the three horizontal layers of plants may vary to create different spatial effects. What about the other nine months? This is because the sun is at a relatively high angle in the sky when shining from the south at midday, thus producing a comparatively shallow area of shade to the north. However one approaches season, it is one of the most challenging aspects of residen­tial landscape design. The extent of plant variation incorporated in any given residential site is a matter of judgment. If this guideline is followed, the installation of immature nursery-stock plant materials will at first appear spotty because there will be space between individual plants. Figure 11—80 shows the graphic differences for showing plant materials in a functional diagram, preliminary design, and master plan of a selected portion of a site. As a group, coniferous evergreen plants have some of the darkest foliage of all plants, though exceptions do exist. Though the exact configuration and amount of shade in these areas varies with the shape, size, and density of a tree, the general characteristics and suitability for planting are similar to the distinct microclimates that exist around a house. Plants under a tree canopy either need to be more drought tolerant or need to be supplemented with irrigation or other means of watering during hot summer months. There are several techniques for studying seasonal shifts. There should be some balance between using some plants for repetition throughout a site (Figure 9—22) and other plants primarily to extend the plant palette (Figure 11—70). Deciduous plants can also be used in planting for their flowers. because of various ecological conditions might suggest a similar response in a resi­dential landscape located there. A frequent mistake is to design exclusively for summer, a problem that is reinforced by countless plant pictures in books and magazines taken during the summer. In some northern regions, summer is, in fact, a relatively short three months or so out of the entire year. It is not easy to think in terms of a dynamic, changing land­scape. Annual, perennial, and woody plants, including a mix of deciduous, coniferous evergreens, and broad-leaved evergreens, should all be used to establish visual interest in a landscape. The reader is urged to review the var­ious techniques for establishing unity, including mass collection, dominance, repeti­tion, interconnection, and unity of three. Coarse-textured plants can also visually move toward a viewer, thus making distance across a space feel shorter, as indicated in Figure 11—76. Figure 11-61
The three horizontal layers of plants may vary in depth throughout a planting bed. • Irrigation or other means of watering are often necessary because plants dry out quickly here. provides stability and contrast to the more shifting quality of deciduous plants. The determination of shade from proposed trees is more difficult because of the initial tree size and future growth rate. Similarly, there are different areas of sun and shade exposure around and below trees. Horizontal layering of plants is also recommended within individual planting beds to furnish a feeling of depth and to create a tapestry of plant forms, colors, and textures displayed one against another. Spring, summer,

Figure 11-65
Rows and blocks of plants reinforce the character of modern and contemporary designs. • Spring flowering bulbs and shrubs located here will bloom later than those planted on the other sides of the house because there is less sun here. Likewise, these conditions tend to vary throughout a residen­tial site. The third way of arranging plants is a combination of blocks and drifts. Spring flowers, autumn fruit, and winter branch structure are often better seen when placed against a dark background, as in Figure 11—73. Ideally foliage, flowers, and fruit should alter in a continuing sequence throughout the year, not all at once in one season. Locate Plants in Proper Ecological Habitat Plants should be organized and se­lected based on the habitat where they are located. East side of house:
• This is a good location for plants that require partial sun/partial shade condi­tions, especially those that benefit from gentle morning sun and generally cool temperatures. Shade-loving plants should not be planted too far north of a shade tree, or they will be in the sun during mid-summer. Figure 11-57
A planting design should be composed of three vertical layers of plants. Plant materials should not be arranged based on the designer’s personal preferences for appearance but rather on a conscious effort to continue the design theme established early on in the design process. Studying plants in layers helps the designer to create outdoor rooms, to provide visual depth, and to establish engag­ing complexity in the landscape. autumn, and winter are the most notable seasons. Organize Plants in Layers Another concept for planting design is to think about and use plants in both vertical and horizontal layers. Figure 11-71
Annuals and perenni­als are best used as accents in strategic locations near en­trances and on prominent peninsulas of a planting bed. The middle layer is the vertical plane of planting design and is established by both shrubs and tree trunks. First, all plant materials should be drawn in the plan as mature or near-mature plants. It is frequently desirable to establish contrasts of color and texture among these horizontal layers so that each layer “reads” against the others. Plants can be located in straight lines to form rows or placed in a series of paral­lel rows to form geometric blocks, as seen in Figure 11-63. Many ornamental deciduous shrubs and trees have attractive spring flowers that merit strategic placement in a de­sign. Figure 11-79
The area of summer shade is greater on the east and west sides of a tree in comparison to the north side. Attention should be given to this layer’s density and height above the ground. The de­sign of the ground layer occurs early in the planting design process, concurrently with form composition, because planting beds occupy one of the largest areas of the ground plane of a site. Plants that are grouped together are more visually unified (the principle of mass collection) than those that are scattered about as individual elements. Thus, the landscape designer must think of both the short-term and long-term microclimatic consequences of proposed trees. Fortunately, many broad-leaved evergreen plants also have attractive foliage texture, which makes them appealing even when not in flower. This character of plants is also suitable for or­thogonal modern designs or contemporary designs where rows of plants form a com­plex pattern of overlapping lines and forms, as shown in Figure 11-65. Too much similarity among the horizontal layers makes a plant composition that is one undistinguished mass of plants with little excitement. The foliage shape, a plant’s overall growth habit, and the distance from which a plant is viewed also affect plant texture. Their relatively fixed appearance
Figure 11-73
Deciduous plants are often used well as foregrounds while coniferous evergreen plants provide dark backgrounds. There are several other things that should be kept in mind about the planting habitat around trees:
• The sun/shade zones that exist on the east, south, and west sides of a shade tree actually extend below the tree canopy because of the sun angle. Drifts of plants should not be used in formal and modern design styles. Fine-textured plants have an opposite effect and tend to recede away from a viewer. A win­ter landscape with too many deciduous plants will lack weight and be too transparent because of the lack of evergreens (top of Figure 11—72). Deciduous plants should be used in a planting for other reasons as well. This is especially true of shrubs and small trees. Pointed leaves establish a sharp texture, round leaves produce a neutral texture, and small, needle-like foliage forms fine textures. It is common to work back and forth between these two layers, adjusting one to the other. Foliage texture is more lasting in plants than in flowers or fruit, so it has greater visual impact over time. The middle ground can be formed with low shrubs and perennials. The foreground is frequently established with ground cover and/or annuals. Rows and blocks of plants should be used in formal or axial designs where rectangular geometry prevails, as in Figure 11-64. The two opposite styles are often attractive complements to each other. Large trees can be drawn at 50 percent to 100 percent mature size because they take many years to reach full growth. • The largest areas of shade occur on the east and west sides, not the north side of the shade tree, as indicated in Figure 11—79. These equate to the ground plane, vertical plane, and overhead plane of outdoor rooms described in Chapter 2. • This is an ideal location for native woodland edge plants and most broad­leaved evergreens that require a protected transitional zone. Woody plant materials are those with perma­nent woody structure that exist in the landscape throughout the year. Figure 11-68
Example of plants in a combination of rows and

regions, it is important to use plants that are attractive during an annual dry period and other plants that respond to rain after the dry period has ended. All three layers need to be considered in concert with each other so they function as a coordinated composition. Although coniferous evergreen plants evolve with growth, they do not change dramatically from one season to the next. This requires the designer to be familiar with plants and their mature sizes. • Plants located here must be drought and heat tolerant because this is the hottest side of the house; in many ways, this is the harshest microclimate of all for growing plants near a house. Typically, one drift of plants is layered on others to form a complex pattern of heights, colors, and textures within the planting area. It is important to consider these seasonal variations because plants are not static elements. • Planting areas directly below the tree canopy are typically drier than planting areas outside the canopy because the tree foliage catches and holds some precipitation. Plant texture is the visual, tactile quality of plants and is primarily the result of foliage size. Typically, ideal growing conditions for plants can be classified into three categories of sun exposure: full sun, partial sun/partial shade, and shade. By contrast, a landscape dominated by coniferous or broad-leaved evergreens frequently tends to appear static and fixed, as if composed of inanimate objects. oompoged oF mOHipfe
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Figure 11-56
Plant masses should be composed of multiple plants of the same species. Design for Different Seasons Another consideration for planting design is to plan for different seasons of the year. Many successful

Figure 11-58
The three vertical layers of plants should be "seen" and considered when studying a design in plan view. Vertically, plants typically occupy three primary layers: ground, middle, and canopy, as seen in Figure 11-57. designs allow each vertical layer to be designed with a different configuration as long as it still fits the other two, as seen in Figure 11-59. A canopy layer may also be desired to extend the height of a planting area and to provide shade and protection over plants located below. Where the size of a planting bed allows, fore­ground, middle ground, and background layers can be formed with different heights of plants, as illustrated in Figure 11-60. The diagram is the most generalized, and the master plan is the most detailed. Likewise, deciduous trees can be used to express a sense of buoyancy and airiness when they occupy the canopy layer in a planting composition, as portrayed in Figure 11—74. As a group, broad-leaved evergreen plants are noted for their showy spring flowers and are often placed in the landscape for this quality. Coniferous evergreen plants can also provide visual weight in a planting composition. and interest, and collectively they express a sense that the landscape is indeed alive. Woody plants are also the most prominent and sometimes the only plants in a winter landscape in northern climates. This method of organizing plants is a stylization of the agrarian practices of lining plants in rows for cultivation and irrigation. The rows of plants give structure and order to the planting while the interior provides a sense of randomness. When presenting preliminary plans to clients, it is important to tell them that the plant arrangement portrayed may take several years or more to achieve. The sun/shade zones for existing trees are relatively easy to determine through actual observation or calculation from sun charts based on the size and height of the trees. Many plants respond to and often change with annual climatic cycles, even in regions that have a seemingly uniform climate. For example, plants that emphasize flowers in spring, attrac­tive foliage texture in summer, vibrant color in autumn, and interesting trunk and branch structure in winter highlight important qualities of each time of year. Most broad-leaved evergreen plants require acidic soil and shade or partial shade conditions for proper growth. The amount of sun exposure at any given location on a residential site is primarily affected by the house and both exist­ing and proposed trees. Consequently, coniferous evergreens are good plants to place as backgrounds to deciduous plants or accents (Figure 11—73), or near the ground as visual anchors in a design (Figure 11—74). It is in some ways easier to design building interiors where the elements remain relatively fixed over a period of time. It is easy to forget the presence of all three vertical plant layers when looking at a plan view of a design as in Figure 11-58. The drawing of in­dividual plants within a mass is usually reserved for the master plan. Shrub Masses On preliminary designs, it is typical to represent shrubs as masses without distinguishing the individual plants within these masses. Drifts are amor­phous, naturalistic masses of plants that are curved and/or irregular in their overall shape, as in Figure 11—66. Woody plants often form the architectural edges around the perimeter of outdoor spaces and provide the back­ground in plant beds. separated and sccrtjereti
Figure 11-55
Plants should be organized in masses. Figure 11-74
Deciduous plants can be used successfully to establish a light canopy while coniferous evergreen plants provide a dark anchor near the ground. Among woody plant materials, a balanced mix between deciduous, coniferous evergreens, and broad-leaved evergreens should be the goal. • Plants that cannot tolerate the drying effect of summer wind exposure or the damaging consequences of cold winter should be avoided in this location. Often the rows and blocks are linear and rectangular in nature. Massed plants are often healthier, too, because they protect one another from sun and wind. • Irrigation or other means of watering may be necessary because plants dry out here more quickly because of continuous sun exposure. West side of house:
• Plants grown here must benefit from the intense, hot, afternoon sun. Then plants, often perennials and/or annuals, are located in drifts within this architectural outline. With this technique, plants are typically placed in rows or blocks to form a frame around the outside of the planting area, as in Figure 11—68. Does the landscape disappear then? Undesirable: – too menu Desirable: mceses a re
individual pbrrte. Some planting areas may benefit from only one or two layers to create special visual effects, as in Figure 11-62. Consequently, woody plants should be the first plants organized in terms of process. Almost every geographic region has distinct seasons of one type or another. Such factors as sun exposure, wind exposure, soil moisture, soil composition, and soil pH all affect the growing conditions of plants. Desirable: ptonterraseed into ore group
in the section on design principles in Chapter 9. the south side, as illustrated in Figure 11—78. The appearance and health of plants is linked to seasonal fluctuations. Use a Variety of Plant Types As a general rule of thumb, it is advisable to use a variety of plant types in any planting scheme. Formal and modern design styles typically require more control and simpli­fication of a plant palette, and an informal or cottage style accommodates a broader range of plants. In general, large leaves generate coarse texture and small leaves produce fine texture. Drifts of plants are an attempt to replicate the organiza­tion of plants in natural habitats and should be used to complement designs that are curvilinear, naturalistic, or cottage style, as in Figure 11—67. Figure 11-77
An example of a sun exposure map used to determine appro­priate plant locations. • Plants that require a moderate sun/shade condition should generally not be placed here unless other means of creating shade is provided. In doing this, the designer should be aware of three broad ways of organizing plants: (1) in rows and geometric blocks, (2) in drifts, and (3) in a combi­nation of blocks and drifts.

Updated: 31.10.2014 — 22:43