How to Care for Ornamental Grasses

Ornamental grasses have increased in popularity among home gardeners because of the way they look and their low-maintenance needs. Like all garden plants, though, they require some seasonal care, and knowing when to provide that care is just as important as knowing what care to provide.

Cool-season evergreen or semi-evergreen ornamental grasses, such as blue fescue (Festuca glauca), which is hardy in U.S. Department of Agriculture plant hardiness zones 4 through 8, can be groomed by removing brown foliage by hand or with a rake in spring. Cut back no more than one-third of each plant.

The best time to cut back warm-season ornamental grasses, such as Miscanthus varieties (Miscanthus spp. and cvs., USDA zones 4 through 9, depending on the variety) is in late winter or early spring, right before their new growth resumes. If your ornamental grasses do not provide winter interest or present a fire hazard, then consider cutting them back in fall as soon as they turn brown.

Because grasses often have sharp-edged blades, wear gloves to protect your skin from cuts.

Gloves

Twine or tape

Measuring tape

Sharp garden shears, string trimmer or power hedge trimmer

Bundle the tops of an ornamental grass plant's blades together in your gloved hand. Secure the blade tops together with twine or tape.

Cut back the grass blades to a height of 4 to 6 inches by using sharp garden shears for that task. In a small area with several clumps of grasses requiring a "haircut," however, a string trimmer can be used in lieu of garden shears. Using a power hedge trimmer to cut back well-established plants is another option.

It is time to divide ornamental grass plants when they become too large or their centers are dying. Divide both cool- and warm-season ornamental grasses in spring.

When dividing a small plant, dig up its entire root ball with a trowel or shovel. Carefully separate the root ball clump, into smaller pieces -- with grass blades attached to each piece -- by using your gloved fingers or a sharp pair of pruners. Then replant the divisions at the same soil depth at which they grew previously, and water their soil well.

Divide a larger established ornamental grass plant in the same way you divide a small plant. Divisions taken from the outer edges of a large clump, however, have the most vigorous root systems that are ideal for replanting.

Long-sleeved shirt

Long pants

Gloves

Sharp garden shears or string trimmer

Sharp spade, ax or saw (optional)

Sharp shovel

Pruning shears

Wearing a long-sleeved shirt and long pants will protect your arms and legs from grass blade cuts.

Cut back an ornamental grass plant that you want to divide, making it 4 to 6 inches tall. Using sharp garden shears or a string trimmer for that task.

Cut the plant clump into four sections. Using a sharp spade, ax or shovel usually works, but using a saw may be necessary to cut through the tough mass of roots of an overgrown, mature clump.

Dig each section out of the ground. Trim off and discard the dead core material of the sections by using pruning shears.

Replant the sections as soon as possible, placing them at the same soil depth at which they grew previously. Water their soil well.

Ornamental grasses do not require soil high in fertility to thrive. In fact, too much nitrogen can cause them to flop. If ornamental grasses' vigor and leaf color are poor, then apply a 10-10-10, granular fertilizer to them in spring, using 1/4 cup per plant. Scatter the fertilizer on the ground around each plant, and water the soil well.

Although ornamental grasses are seldom bothered by pests, any mites or aphids detected on them may be blasted off with a strong stream of water.

Newly planted ornamental grasses require water on a regular basis for one year, until they become established. Once established, most ornamental grasses do well without extra irrigation except during times of drought.