Horticulture Principles and Practices

Blooming bushes 1. Blue

Blooming bushes 1. Blue mist shrub (Caryopteris spp.)—This bush is adapted to zones 6–9 and has beautiful flowers in fall. 2. Scotch heather (Calluna vulgaris)—The species thrive best in zones 4–7 and bloom in fall. 3. Witch hazel (Hamamelis virginiana)—This fall-blooming shrub is adapted to zones 5–8. Shrubs with colorful fruits 1. American cranberry bush (Viburnum trilobum)—This species is grown in zones 3–7. 2. David viburnum (Viburnum davidii)—Adapted to zones 7–9. 3. Firethorn (Pyracantha spp.)—The shrub is adapted to zones 5–10. 4. Heavenly bamboo (Nandina domestica)—The shrub is adapted to zones 7–9. 5. Linden viburnum (Viburnum dilatatum)—Adapted to zones 5–8. 6. Red chokeberry (Aronia arbutifolia ‘Brilliant’)—This shrub is adapted to zones 4–8. SUMMARY Trees and shrubs are perennial plants. The largest plants in the landscape, trees may be deciduous or evergreen and broadleaf or narrowleaf. Principles for selecting annual bedding plants apply to selecting trees and shrubs. The critical caution is that once planted, trees remain for a long time in their spots (i.e., until they are cut down or die) and as such should be selected and located with care. Some trees and shrubs flower; they are purchased from the nursery as either bare-root, balled and burlapped, or container-raised plants. After planting, trees may be staked or guyed to hold them upright. Certain trees change color during the fall season and can be strategically located to enhance the landscape during the season. Trees provide shade, and shrubs are common hedge plants. 17.21 BULBS, CORMS, TUBERS, AND RHIZOMES Plants with underground structures (e.g., bulbs, corms, tubers, and rhizomes) have a wide variety of uses in landscape design. These plants are modified roots, stems, and leaves that have the capacity to store large amounts of water and plant food. Sometimes the term bulb is used loosely to include all of the categories of plants described. Bulbs are used to add color to the landscape. They are very effective when placed in a bed with perennial plants. They are most effective when massed. Bulbs such as tulips have a spectacular array of colors. Flowers of bulbs, as well as plant form and height, vary widely. For example, lilies are tall and should be planted behind short bulbs such as grape hyacinth. Fall-planted bulbs provide landscape color in early spring. Some bulbs are planted in spring (Table 17–12). After the fall crops have withered, summer annuals TABLE 17–12 Plant Giant allium Amaryllis Peruvian daffodil Dutch iris Tiger flower Spring-Planted Bulbs Scientific Name Allium giganteum Hippeastrum x hybridum Hymenocallis narcissiflora Iris hollandica Tigridia pavonia 17.21 Bulbs, Corms, Tubers, and Rhizomes 537

Naturalized Plant A plant introduced from one environment into another in which the plant has become established and adapted to a given region by growing there for many generations. may be planted in the same area as the bulb. Certain species of bulbs such as Crocus and Galanthus may be planted to naturalize in the lawn. In naturalizing, these bulbs are dormant in fall and summer so that the lawn can be enjoyed during that period. In winter and early spring, when the lawn is dormant, these naturalized bulbs flower to keep the space attractive year-round. Species that lend themselves to this treatment include crocus, daffodil, scilla, early narcissus, spring start flowers, and glory-of-the-snow. When a lawn is planted in this way, it should not be mowed until the bulb begins to wither, which may take eight to twelve weeks after peak flowering. 17.21.1 ESTABLISHMENT Site Selection and Preparation Bulbs prefer neutral soils that are well drained and loamy. Acidic soils (less than pH 5.9) should be limed. If necessary, the organic matter content of the soil may be increased by adding compost or sphagnum moss. The bed should be well prepared and loose since some bulbs are planted as deep as 10 inches (25.4 centimeters) in the soil. Some form of complete fertilizer (10:10:10) or slow-release bulb fertilizer should be incorporated into the soil during preparation for planting. Because bulbs generally prefer sunny and warm locations, the planting site should experience full sun for at least four hours daily and be protected from strong winds. Beds that face south or west receive adequate exposure to light. Planting Bulbs As indicated previously, some bulbs are planted in spring and others in fall. Bulbs differ widely in depth of planting (Figure 17–13). Begonias are planted shallowly (about 1 inch or 2.54 centimeters deep) and daffodils deeply (about 10 inches or 25.4 centimeters deep). It is important that planting depth be uniform in the bed to promote even flowering. Spacing is also variable. Since bulbs have more aesthetic appeal when massed, close planting is desirable. For large bulbs such as daffodils, five bulbs per square foot (0.18 square meter) is adequate; ten to fifteen bulbs per square foot (0.18 square meter) is recommended for small bulbs such as crocus. However, the deeper they are planted, the wider they are spaced. Spacing is also influenced by the garden plan. Bulbs such as daffodils are easy to orient in the soil since they show roots at the bottom. Others, such as dahlia and anemone, do not have clear upward-facing parts. If roots are hard to find, the bulb can be planted sideways. Bulbs can be planted with the aid of a trowel or spade. A bulb planter (hand and foot models are available) facilitates the planting activity. It is used to remove plugs of soil from the ground, into which the bulbs are placed and covered up. The recommended depth of planting and spacing are indicated on the packaging. The plot should be watered well after planting. cm 0 5 10 15 0 in 1 2 3 4 5 6 7 Caladium; tuberous begonia; dahlia Crocus; hyacinth Iris Canna Narcissus; gladiolus Tulip; lily Amaryllis FIGURE 17–13 Planting depth for various plants with underground swollen structures. (Source: For (b) © Dorling Kindersley) 538 Chapter 17 Installation of the Landscape