Extension News

Fall for Ornamental Grasses

maiden grass plumes

Note to media editors: This is the Iowa State University Extension Garden Column for the week of Oct. 5, 2007.

10/1/2007

Cindy Haynes
Extension Horticulturist
Iowa State University

Every year as we enter the fall season, I realize how much I admire ornamental grasses in the landscape. They offer color, texture, movement and a bit of sophistication to the garden. Grasses also combine easily with woody and herbaceous perennials.

Finding just the right grass, however, can be intimidating; many different species and cultivars are used in home landscapes. Below are some of the many ornamental grasses readily available and suitable for Iowa gardens.

Start Small
For smaller spots in the landscape, try adding one or more of the species below to your collection of small shrubs, herbaceous perennials or annuals.

Dwarf Blue Fescue – (Festuca ovina var. glauca) The dwarf fescues are one of the smallest of the ornamental grasses, staying under one foot tall. Several cultivars, such as  ‘Elijah Blue’, have metallic-gray foliage and mounding habits.

Dwarf Fountain Grass – (Pennisetum alopecuroides) Although some species will reach 4 to 5 feet in height, the dwarf types like ‘Hameln’ generally stay below 2 or 3 feet. Their “foxtail” like plume is an attractive feature in late summer and early fall.

Blue Oat Grass – (Helictotrichon sempervirens) This grass reaches 3 feet in height and has beautiful blue-gray, fine-textured leaf blades. It is stunning throughout most of the season and combines well with most herbaceous perennials.

Little Bluestem – (Schizachyrium scoparium) Little Bluestem is a native grass that is often underused in the landscape. Plants reach 2 to 3 feet in height and have dark-gray foliage. Look for cultivars like ‘The Blues’ for more bluish summer foliage and reddish fall color.

Go Tall
If you are looking for a grass with a little more “presence” or “stature” in the garden, the listing below will get you started.

Feather Reed Grass (Calamagrostis actuiflora var. stricta) is one of the most popular ornamental grasses grown today. Plants are 4 to 6 feet in height and have dark green leaves and narrow, tan plumes in early summer. ‘Karl Foerster’ is a popular cultivar that is noted for its adaptability and attractive plumes. Also look for ‘Overdam’, a cultivar with variegated foliage.

Switchgrass (Panicum virgatum) is a native grass that is becoming more popular in landscapes. The plants are durable, reach 4 to 6 feet in height, and are available in many different cultivars. ‘Heavy Metal’ and ‘Shenandoah’ have dark metallic summer foliage and reddish fall color. ‘Dallas Blues’ has blue-gray summer foliage that also turns a good orange-red in fall. The open plumes of ‘Strictum’ begin to bloom earlier than other cultivars, but remain showy throughout the season.

Maiden Grass (Miscanthus sinensis) cultivars also are primary players in the ornamental grass market. Their heights of 5 to 7 feet make them perfect backdrops to showcase other perennials. Many of the cultivars from this species are noted for ornamental foliage and late display of flower plumes. Look for the green and white striped leaves of ‘Variegata’ or check ‘Strictus’ or ‘Zebrinus’ for leaves with yellow stripes across the blade. Other cultivars worthy of mention are ‘Gracillimus’ for its narrow dark green leaves, or ‘Morning Light’ for its narrow greenish white leaves. ‘Silberfeder’ offers a striking display of plumes earlier in the season. Several other Miscanthus species are equally suitable for Iowa gardens. Look for Miscanthus sinensis var. pupurescens for great reddish fall color. Try Miscanthus floridulus ‘Giganteus’ if you want plants that will reach more than 10 feet in height.

Ravenna Grass (Erianthus ravennae) is often called Hardy Pampas Grass. It commands attention when in flower in late summer because it often reaches over 10 feet in height. This is a wonderful grass to add drama in the landscape, or to hide an unsightly view.

Maintenance Tips for Growing Ornamental Grasses
• Most ornamental grasses thrive in sunny sites with well-drained soils, so plan and plant accordingly. Check the labels carefully for mature size and site preferences.
• After planting, water well as needed to get plants established. Unlike your lawn, watering after establishment is needed only in times of drought.
• Ornamental grasses rarely need fertilizer. Once a year or once every other year, scatter some granular fertilizer around them in the spring. Otherwise, save the fertilizer for your lawn.
• Don’t cut back ornamental grasses in the fall. Many will stand for a large part of the winter. Even tan and dead, they are quite attractive after a snowfall.
• Clean up or cut back ornamental grasses in early spring before the new growth appears.
• Division is sometimes necessary to keep ornamental grasses thriving in the landscape. If you notice the center of your grass is not as full as before, it may be time to divide it. Division is best done in early spring when the new growth appears.

While these ornamental grasses make great additions to any garden, don’t stop with the ones on this list. Consider many of the other prairie natives like Side Oats Gramma (Bouteloua curtipendula) or Big Bluestem (Andropogon gerardii). Or consider non-natives like Tufted Hair Grass (Deschampsia caepitosa) or Moor Grass (Molina species).  Annual grasses, such as Purple Fountain Grass (Pennisetum species), work well in containers and in open spots in the landscape. By this time next year, you too will be impressed with what a few ornamental grasses can do to add interest to any landscape.

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Contacts :

Cindy Haynes, Horticulture, (515) 294-4006, chaynes@iastate.edu

Jean McGuire, Extension Communications and Marketing, (515) 294-7033, jmcguire@iastate.edu