Ornamental grasses have been used in gardens since before the Renaissance-and are currently enjoying another. This is not surprising, given today's enthusiasm for low-maintenance gardens and an increasing awareness of the environmental benefits of native plants. Varied in form, scale and texture-from ground-hugging to gigantic, from thread-fine to spiky to pillow-soft-grasses thrive in difficult areas such as steep slopes or poor soils. Many look good grown in pots and require less care than annuals. Their design potential is most exciting for creating structure and atmosphere in the garden.
Grasses are beautiful in all seasons, undulating in the wind and catching and playing with the light. Some, such as plume grass (Saccharum ravennae), are best grown as specimen or single plants; others, such as hakone grass (Hakonechloa) or dropseed (Sporobolus), show to best advantage when grouped. A number have distinctive summer colour or variegation, and most have excellent fall and winter colour. The taller ones usually hold their form right through the winter and pair well with conifers such as yew, cedar and juniper. In spring, their delicate new growth is lovely as a backdrop for late-blooming bulbs, while in early summer they provide a foil and filler for perennials and annuals. On frosty fall mornings, grasses sparkle in the long, low sunshine. But mid- to late summer is their prime time, when they mediate and make richer the strong yellows of daisy-like perennials.
In new gardens, grasses anchor and give shape to empty space, growing to nearly their full height in their first season, but are easily moved when slower-growing woody plants are acquired. They can define a boundary, screen a patio or window for privacy, separate garden areas or create a secret place for children. They're also handsome backdrops for other plants and make excellent groundcover in sun or shade, as Gertrude Jekyll pointed out a century ago. Planted in groups, fountain grass (Pennisetum spp.), moor grass (Sesleria spp.) and Prairie dropseed (Sporobolus heterolepis)-native from Quebec to Saskatchewan and south-make no-care borders, while sedge (Carex spp.) and ornamental fescues (Festuca spp.) create excellent no-mow lawns; F. ovina is effective when used for green roofs. Miscanthus sinensis ‘Silberspinne', attractive as a single clump, is positively magical in late July when planted as a long, dense hedge-a sinuous chorus line moving in the wind.
Though grasses have been used in European garden plans for centuries, they really caught on as a design medium in North America in the 1970s, when Washington, D.C., landscape architects Wolfgang Oehme and James Van Sweden revolutionized planting ideas with their planting designs for residences and public buildings. They used grasses as a graphic medium, planted with low-maintenance perennials and naturalized bulbs to create stunning blocks of form and colour. Oehme and Van Sweden called their innovative style the new American Garden, and their plantings, which are still a delight, inspired innumerable copies. So how do you adapt these ideas for your garden?