Ornamental Grasses Cultural Instructions
Ornamental grasses can also be classified according to their growth habit (shown at right). Most ornamental grasses form clumps, rendering them noninvasive and suitable for use as specimen plants or for massing. These grasses exhibit a wide array of architectural forms, including:
As a rule, ornamental grasses are tolerant of soil conditions, although most prefer a well-drained garden loam fairly high in organic matter. Most ornamental grasses are full-sun plants and should receive at least six to eight hours of direct sun each day for best growth. Application of between one and two pounds per 100 square feet of a complete, general-purpose garden fertilizer such as 5-10-5 or 10-10-10 before planting should supply adequate nutrients for quick establishment. Once established, ornamental grasses should not be heavily fed; application of one-half to one pound per 100 square feet of a complete, general-purpose garden fertilizer is sufficient. This is equivalent to about one-fourth to one-half cup per plant. Apply fertilizer in the spring just as new growth emerges. Excessive fertility (especially in the form of nitrogen) encourages lush, weak growth unable to stand on its own. Additionally, late applications of fertilizer to warm-season grasses tend to reduce their winter hardiness.
Cool-season ornamental grasses can be planted in the spring or fall; warm-season grasses should be planted only in the spring. Fall-planted grasses benefit from a light mulch applied after several hard freezes have occurred during their first winter. Winter protection in succeeding years usually is not warranted. Spacing ornamental grasses is a matter of personal preference and intended function in the garden. For small groupings, spacing plants at intervals equal to their mature height is considered satisfactory. Grasses should be watered regularly during their first season of growth to encourage the establishment of a deep, vigorous root system. Once established, ornamental grasses usually require supplemental irrigation only during periods of hot, dry weather. This is especially true for warm-season grasses. The amount of water to apply depends on several factors, including species, exposure, soil type and size. Additionally, most ornamental grasses are remarkably pest-free and usually do not require application of pesticides.
Routine maintenance procedures include cutting back ornamental grasses in late winter or early spring to remove old, unsightly growth and to allow new growth to develop without being shaded by the old. Clump-forming grasses should be divided regularly to keep the clump “young” and attractive. Older clumps tend to die in the center, leading to an unattractive shape and appearance. Frequency of division depends on species, soil fertility and exposure, but dividing every third year is a safe rule of thumb for most species. This should be done in late fall or early spring when the plant is dormant.