Choose According to Growth Habits
Before planting you should also understand the growth habit of the grass. Grasses can be either clump forming or rhizome forming. The latter is often called "running" grass (yes, it can be invasive and will vary from area to area - check with your country extension office before you plant). The clump forming grasses will grow in very nice, neat mounds or clumps. They tend to mix very well with other perennials and will not become invasive. They will increase in girth slowly over time.
Make sure you choose a grass the right size and shape for your landscape needs. Some ornamental grasses get extremely tall! Grasses are also available with variegated leaves - these can be horizontal or vertical bands of color, patches, stripes or spots. Textures vary from very fine and feathery to thick strap-like blades. The late summer and autumn seed heads vary widely too - from frothy or feather-like whites, pastels and deep, bright colors, to the more coarse bead-like or rope-like types. The best ornamental grass gardens will include a collection of different types that provide size, color, seed head, and texture contrast.
The rhizome forming grasses spread by underground stems and can become very aggressive and invasive. These grasses have their place but it may not be in a well-tended perennial border since they can soon take over an entire area.
Before selecting a grass, be sure to understand how it grows so you won’t be planting a future problem. Some attractive but aggressive grasses include Blue Lymegrass, Cordgrass, Ribbongrass, and Silver Banner Grass (miscanthus sacchariflorus) These can be useful for covering slopes to prevent soil erosion, but do use them with care.
Cool Season Grasses
Cool season grass will start to grow early in the spring and may even remain semi-evergreen over the winter. They also seem to do better and have better foliage when they are cool or if they are given sufficient water during drought periods. If they are not watered during drought, they tend to go dormant resulting in brown foliage.
These grasses may require more frequent division to keep them healthy and vigorous. If not, they tend to die out in the center. For the ones that remain semi-evergreen, you should only cut off the brown or winter injured foliage in the spring. Some of the more popular cool season grasses include, Fescues, Blue Oat Grass (Helictotrichon), Tufted Hair Grass (Deschampsia), and Autumn Moor Grass (Sesleria).
Warm Season Grasses
Warm season grasses will do better during warmer times of the year and remain good looking even when temperatures are high and moisture is limited. Warm season grasses do not begin to show growth until the weather becomes stable and the soils warm. The previous seasons growth usually browns out in the fall requiring the cutting back of plants to about 4-6 inches in the spring.
|Warm Season Grasses|
Japanese Silver Grass
Warm season grasses usually do not require as frequent division as cool season grasses. Some warm season grasses include Northern Sea Oats (Chasmanthium), Japanese Silver Grass (Miscanthus sp.), Hardy Pampas Grass (Erianthus and Cortaderia), Perennial Fountain Grass (Pennisetum), and Switch Grass (Panicum).
Planting and Propagating
As with any perennial, preparing the soil before planting will insure success. Prepare the bed by deep tilling and adding organic material. Ornamental grasses do not require high amounts of fertilizer. Adding about one pound of a general-purpose fertilizer (like 10-10-10) during soil preparation per 100 sq. ft. of planting bed should be sufficient.
Ornamental grasses can be planted in the spring or the fall. The advantage of spring planting is to give the plants adequate time to develop a good root system before winter. Fall planting is often not as reliable without some additional precautions, particularly in years with early or severe winters. You should try to complete fall planting during August and September. Then provide a light cover of straw or hay during the first winter for best results.
Apply the mulch after several hard frosts. Plants should be planted no deeper than their previous growing depths and should be well watered after planting. Maintaining uniform soil moisture around the plant hastens establishment. Plants planted too deep tend to develop root diseases or simply rot in the ground.
Perennial grasses can be propagated by seed sown in spring or autumn. Established clump forming plants can be lifted and split in the spring. Grasses that form rhizomes can be propagated by cutting the rhizome into sections (each with at least one growing point) and each section planted at the same depth as when it was lifted from the mother plant.
Plants should be well watered the first season after planting so they can develop a good root system. Established plants do not need regular watering, but may need supplemental watering during drought periods. The amount of water will depend on the grass species, the site, and on the quality, size and growth rate desired.
If your area is too moist, increase soil drainage by mixing in sharp sand, or stick to growing sedges or rushes and other ornamental grass types recommended for moist soils (see below).
Cultivate around grass plants to control weeds. Apply mulch to reduce the need for cultivation as well as watering. Mulching also tends to keep grasses in check that have a tendency to be heavy reseeding types.
Winter Protection and Spring Clean up
Grasses do not need to be cut down before winter. In fact, they make a stunning contrast in the winter garden when left standing, plus the foliage helps to insulate the crown of the plant. Cut back the foliage to about 4-6 inches in the spring before growth resumes. When foliage is removed, spring growth will begin earlier. Old foliage left on the plant can delay the crown’s warming and growth by as much as 3 weeks.
To divide your plants depends on how they are spaced and how they look, the appearance of the plants as well as the health should determine if it needs dividing.. Plants suffering from die-out in the center should be divided to improve appearances. Division is done in the spring before growth resumes or in the late summer or fall after the growing season. Plants that bloom late could be divided in the spring.
Ornamental grasses are not bothered by pests, but if you see Aphids, then spray the plant with water from a hose to dislodge the critters.