Stipa gigantea blooms earlier than most grasses, its tall, handsome flower stalks rising from a 2-foot tuft of foliage from June through frost. Their airy transparency is shown off in Valerie Easton's former rockery by being set against the autumn fireworks of a staghorn sumac.

While Nelson's day job is helping 13,000 King County employees find more environmentally responsible ways to do their work, he nevertheless keeps up on all things grasslike. "Have you seen that planting of grasses at the new downtown library?" he exclaims. "In three years it'll really be something." Maybe showing off the Fourth Avenue grass garden to full advantage is the purpose for all those reflective panels on the library's exterior.

It's easy to come up with all kinds of reasons to add grasses to your garden. For one thing, they're drought tolerant. They offer late-season interest, wave in the wind, and are compatible with shrubs and perennials. Nelson points out another, compelling reason: Ornamental grasses are a lazy gardener's best friend.
 

Now in Bloom Clematis rehderiana is an autumn-bloomer that appears far more delicate than it is. The softly hairy, serrated leaves dangling with bunches of soft-yellow, bell-shaped flowers grow vigorously to cover arbors, walls and pergolas. Provide this late-bloomer with full sun, cut it back hard in early spring, and you'll be rewarded with sweetly fragrant, pale flowers from late summer through October.

"It just takes one day a year to maintain ornamental grasses," he says. "Unfortunately, that day is in late February or earliest March." Despite the wet, dark and cold, you need to go outside and cut back, transplant or divide just before grasses break dormancy and start growing. The absolutely worst thing you can do to a grass is to let the roots dry out as you move it. There's little chance of that happening in late winter.

Deciduous grasses will be lying in dead heaps, and you want to cut them back to within about 6 inches of the ground so the new foliage can get through. How to cut back those near-woody clumps of big old miscanthus? Nelson recommends loppers, a hedge trimmer or even a chainsaw, but cut it back you must or the new foliage competing with the old will make for a less-than-elegant look.

Now here's the good part: Leave the evergreen grasses alone. They never need cutting back, unless they've been freeze-damaged or have brown tips from environmental stresses. If your carexes or sedges are looking a little ratty, you can trim them back carefully, never by more than a third, keeping in mind that the goal is bang trim not buzz cut.

Another thing: Don't get carried away on your one day of maintenance and pour on the fertilizer. "Fertilizer turns grasses into dinner," says Nelson. That's because too much nitrogen causes lush growth that's susceptible to pests and diseases. Also, fertilizer discourages flowering, preventing grasses from putting on their summer and autumn show. There are exceptions. The supremely beautiful prima donna Hakonechloa macra 'Aureola' prefers plenty of supplemental watering and rich soil. At the other end of the spectrum, pennisetums are happy to be left alone in baking hot gravel.

Among Nelson's picks

• Stipa gigantea. Straw-colored 6- to-8-foot stalks; June flowers create a major presence in the garden until frost.

• Calamagrostis x acutiflora 'Karl Foerster,' or feather reed grass. Topped by a cloud of purple flowers hovering six feet in the air; turns into a dense golden screen that stands up through late winter.

• Panicum virgatum, or switch grass. Red selections such as 'Rotstrahlbusch,' have airy little flowers and glow crimson when backlit by autumn sun.

• Pennisetum orientale (soft pink) and P. alopecuroides (more robust). These tough fountain grasses offer fuzzy bottlebrush flowers and enjoy a well-drained, sunny spot.

• Miscanthus sinensis 'Gracillimus' and 'Sarabande.' These taller species make graceful hedges and screens; foliage stays elegant late into winter. Other Miscanthus cultivars, including the striking, horizontally-banded, 2-foot 'Adagio,' offer foliage in a range of sizes, colors and textures.

. . . and warnings

Invasive, running grasses such as ribbon grass (I wish I'd heard that before I planted the pretty beast) and Elymus arenarius 'Glaucus,' also known as European dune grass or beach grass.

Valerie Easton is a Seattle freelance writer and contributing editor for Horticulture magazine. Her e-mail address is valeaston@comcast.net.

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