Ornamental grasses shine in the fall landscape, adding appeal through color, texture, movement and low incidence of pest problems. Unlike herbaceous perennials, many ornamental grasses have foliage that remains attractive throughout the winter months. They serve to complement the effectiveness of other plants with cold weather interest such as bergenia, English ivy and Japanese spurge. Some also have persistent seedheads that add interest to the winter landscape. Many also are valuable for use in fresh and dried floral arrangements.
Ornamental grasses require supplemental irrigation until they develop a mature root system. Once established, mature plants typically have deep root systems and can extract sufficient water from the soil to maintain growth during drought conditions. If irrigation is necessary, drip or surface irrigation should be used to reduce the incidence of foliar diseases. Many drought tolerant grasses will not grow well if over-watered. Once ornamental grasses mature, the amount and frequency of water required will vary with grass species and characteristics of the site including soil type, sun exposure and wind.
Allowing foliage to remain throughout the winter helps protect the crown from drying out and provides seasonal interest and wildlife habitat. When winter storms and other landscape care activities cause the stems to fall over, remove them to maintain aesthetic quality and avoid damage by small animals. Many gardeners enjoy experimenting with grass species and cultivars that have not proven to be completely winter hardy (ie. Japanese bloodgrass). After the soil has frozen in the late fall, cover these plants with a coarse wood chip mulch, held in place with a device such as a rose collar.
Ornamental grasses are more attractive when dead foliage is not interspersed with living tissues. Before new growth begins, remove the previous years’ foliage to within a few inches of the ground or as close to the crown as possible. Cool season grasses, such as feather reedgrass and tufted hairgrass, will resume growth earlier than warm season grasses like maidengrass and most natives. A hand clipper, mechanical weed whip or other power equipment can be used to remove old growth. Grasses will begin growing earlier if dead foliage is removed in later winter.
The need for plant division depends on the growth rate, spacing requirements and visual appearance. Some ornamental grasses can remain in place for many years without needing division. If the center of the ornamental grass clump shows little or no growth, the plant should be dug up and divided. Remove the dead center clump, divide the actively growing outer edge into smaller pieces and replant. Spring is the best time to divide ornamental grasses, when the stems are 4 to 7 inches long or shorter.
