Perennial ornamental grasses are not entirely maintenance-free when established, but nearly so. There are just a few steps to take to ensure that a grass is healthy from when it is first planted and beyond. A healthy ornamental grass grows fuller, the stems remain upright or arching, depending upon variety, and the plumes or inflorescences make a good show. Miscanthus, fountain grass (Pennisetum), feather reed grass (Calamagrostis) and switchgrass (Panicum) are common choices. They have excellent color and texture and grow well with just a modicum of care.
Choose a site for your ornamental grass; a full-sun situation is best. The University of Illinois Extension recommends turning over the soil ahead of time, preferably in the fall so the soil becomes more workable through winter's freezing and thawing. If the soil is poor, amend it with compost, loam and sand for drainage. Missouri Botanical Garden recommends applying a fertilizer such as 10-10-10 at 1 to 2 pounds per 100 square feet before planting.
Take the plant out of container. Gently loosen the roots if they've grown into the shape of the pot. Dig a hole wider and deeper than the plant by several inches. Add planting mix into the bottom of the hole, then water the planting mix. Set the ornamental grass in the hole to the same level it was in the pot. Backfill, then tamp down lightly until the hole is filled. Water the plant thoroughly.
Water the plant every few days the first week, then thoroughly once a week through its first growing season. This will help the plant establish strong roots. The University of Illinois recommends mulching lightly for the winter with hay or straw, but only after several hard freezes.
Cut back grass to about 4 to 6 inches in the spring before new growth begins. Tie up dead growth with rope or string to allow a better view for cutting. The size of the grass dictates the tool; mature grasses may need electric weed trimmers. The University of Illinois recommends fertilizing each spring with 10-10-10 fertilizer, about 1/4 cup per plant, and a slow-release fertilizer for summer growth.
Mulch with compost or leaves if your climate is cold, according to Bluestem Nursery in British Columbia, Canada. This helps to keep an even temperature. Do not mulch before ground is frozen.
Divide the grass every three to four years, according to the Missouri Botanical Garden. Lift the clump carefully so as not to damage the roots. When the clump is out of the ground, divide it as gently as possible with a sharp knife or spade, preferably into quarters. Plant one division in the same spot. Choose other suitable locations for the other divisions, and treat it as you would any new planting.