How to Grow Grass
Grown singly or grouped for effect, ornamental grasses add variety and movement to any garden or landscape.
For many centuries, grasses have been a key component in European gardens, although until relatively recently these were limited to lawns or meadows. Since the latter part of the 20th century, ornamental grasses have been used more and more in our gardens. Even though they do not have the pretty, colorful flowers of most garden plants, they bring structure, height, texture, fall color, winter silhouettes, and—most important of all—movement. Some, such as Stipa gigantea and molinias, stand well into fall with their stems glowing golden orange, and grasses like miscanthus and calamagrostis remain attractive throughout the winter months and into the spring. The winter garden will look much more interesting if it has some grasses, because they don’t die down in fall like other herbaceous plants. The birds can also feast on the seedheads.
Grasses usually fall into one of two groups: clumpers or spreaders. Some naturally form perfectly behaved clumps, whereas others can take over your garden with their creeping rootstocks. So choose carefully. There is now a large selection of grasses available that do not self-seed or spread wildly. If in doubt, check with your supplier, or take a close look at how the plant is growing. If it makes a neat, dense clump or tussock, it should not run; if you see shoots coming up all over the pot without forming a tight clump, beware. In light sandy soils in particular, grasses, such as variegated gardener’s garters (Phalaris arundinacea), can become invasive and need to be regularly weeded out.
Where to Plant Grasses
You can use grasses as solitary feature plants, or scattered through other plants, or in larger drifts or swaths. How you do it depends on the type of grass you choose and the effect you wish to achieve. Try large drifts of Miscanthus sinensis ‘Kleine Silberspinne’—although not the tallest grass, it is still impressive. Calamagrostis x acutiflora ‘Karl Foerster’ also looks good in a mass. You could use it to create a hedgelike screen, or add depth to a bed or border by scattering it through a planting of smaller flowering perennials.
Since many grasses stand through fall, you can create a beautiful effect by siting them carefully. The flower spikes and orange stems of Molinia caerulea ‘Windspiel’ or ‘Transparent’ glow if they catch the late afternoon sun in fall. As its name suggests, ‘Transparent’, like other molinias, is almost translucent. If you position it at the front of a planting, it creates a see-through screen, and the feathery plumes brush your face as you walk past. Sound and movement add an extra dimension to a bed or border when grasses rustle in the wind. Intersperse them among traditional flowering plants for contrasts of color and shape.
Naturalistic Grass Planting
Designers in Germany and North America have developed a way of planting perennials and grasses that mimics the plants’ natural growth habits. Plants are chosen from a natural habitat with conditions similar to those in the garden. For example, if your garden is partly shaded, you should choose plants that originate from woodland margins, which will thrive in light shade with a few hours of sun each day.
Plants are placed how they would occur naturally. For example, grasses with creeping or spreading roots are planted in drifts and groups. Those that scatter themselves by means of seed are dotted around. Any bare soil is covered with ground-cover plants or mulch to suppress weeds. The result is a community of plants that are allowed to grow and evolve naturally. Caring for such a scheme involves less maintenance than traditional gardening, since plants are not supported or deadheaded, but simply tidied up when they are past their best.
Keeping Grasses Looking Good
Ornamental grasses need little attention to keep them looking good. Most evergreen grasses, including sedges and rushes, only need a trim to remove damaged leaves and old flower stems. The best time to do this is in late winter, before fresh spring growth emerges. Grasses that turn straw-colored in fall should be cut down to the ground in late winter, after you have enjoyed their frosted foliage. New growth will soon emerge. Most grasses will grow in poor soil and thrive on neglect—give them too much water, food, and fuss and they’ll die. Large grasses, such as pampas, are an exception, and need an occasional feeding with a general-purpose fertilizer to keep them vigorous. Grasses seldom need watering, except after planting and while they establish, but if their leaves roll up, it’s a sign they need a drink. Clear debris, such as old stems, using a spring-tined, or grass, rake. Work from the center of the clump and comb out any debris.