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Get to know grassy plants

December 1, 2012

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Ornamental grasses are taking the horticultural field by storm. They delight onlookers in landscapes as famous as England’s Kew Gardens and Fort Worth’s Botanic Research Institute. And they have found favor in home gardens of all kinds – from lavish to simple cottage style.

Why grasses?

Many are drought tolerant, low maintenance and attractive to wildlife. They thrive in settings as varied as coastal to mountaintop. Many are admired for their “flowers,” and others are sought for their coloring. Grasses add form and texture as well as a natural element to most gardens.

Not all plants called grasses are, botanically speaking, true grasses.

However, they serve many of the same purposes in the landscape. For example, some of these “impostor” grasses work well in environments where true grasses will not thrive. True grasses are in the botanical family Poaceae (Gramineae).

Other plants with straplike leaves or flowering structures that resemble true grasses include sedges, rushes and cattails. Narrow-leafed perennials often labeled as grasses include liriope and flax.

What are the distinguishing characteristics of these plants? Grasses have narrow leaves with long, straight veins running parallel to the leaf edges. Their cylindrical stems are hollow except at the solid nodes (joints).

Cattails (Typhaceae) are aquatic or marginal plants, so they are a complementary addition to water features, particularly where their growth may be easily controlled. They have solid stems and flat, narrow leaves and velvety-brown, cigar-shaped flowering structures.

Rushes (Juncaceae) typically have stems that are cylindrical like true grasses, but they lack nodes and tend to be solid rather than hollow. Sedges (Cyperaceae) also lack nodes and have solid stems, but their stems are not cylindrical. They are said to have “edges” and are normally triangular when viewed in cross-section.

Landscape designers are finding more uses for grass-like plants in home landscapes. Sedges, in particular, often work as groundcover or lawn substitutes. Although they may die back in winter, some sedges never truly go dormant in North Central Texas. Many tolerate wetter, less well-drained sites than true grasses prefer, and most perform best in some shade.

The term sedge refers to 3,000-plus species in this family, but about 1,000 of the species comprise the genus Carex. Most ornamental sedges originate from moist or wet habitats in temperate regions, so they are easily adapted to similar settings in home gardens. They are diverse in form, color, size, growth habit and use; they may form tall, dense clumps or run along the ground.

While sedge flowers are not ornamental, the plants sport attractive green, blue, yellow, brown, orange or variegated foliage.

All sedges benefit from removing winter-damaged foliage in late winter to early spring. Plant them according to nursery directions, and be prepared to provide irrigation during extreme drought, especially if they receive extended sunlight.

Sedges used as lawn substitutes or groundcovers are best mowed or trimmed in mid-May, then again in mid-November. Fertilize sedges in fall. Sedges sold in Texas nurseries include:

BLUE SEDGE

Carex glauca requires full to partial shade and moderate moisture. It will thrive in moist soils if they are well drained. Blue sedge grows 6”-12” tall and spreads 12”.

This is a well-adapted deciduous plant that boasts blue-gray foliage. Blue sedge forms clumps, which make it an attractive groundcover. Butterflies like blue sedge as a larval food source.

BERKELEY SEDGE

Carex tumuicola prefers full to part shade and moist soils. Although drought tolerant, it does require water. An evergreen, Berkeley will grow to a height of 8-18 inches. This plant’s dark green arching foliage forms 12” wide clumps that spread by creeping rhizomes. It makes a nice groundcover when planted densely to create a turf-like effect. Mowing enhances its appearance. Berkeley sedge attracts birds.

LEVENWORTH SEDGE

Carex leavenworthii performs best in shade, but will tolerate a half-day of full sun. It grows well in many soil types and grows 6” tall and wide. It is one of the best substitutes for lawn grass, but must be planted densely to achieve this effect. This evergreen is considered drought and heat tolerant.

MEADOW SEDGE

Carex perdentata is an evergreen that performs well in either moist or dry soil and is very heat and drought tolerant. Plant it in full sun or shade, but shade is preferred. This fine-textured sedge will spread rapidly, making it a good lawn substitute.

Resources: Weston Gardens, Bluestem Nursery, Encyclopedia of Grasses

For horticulture answers, call the Texas AgriLife Extension, Hood County, 817-579-3280, or visit the website, hoodcountymastergardeners.org.

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Category: Horticulture Archived