Issue: July 14, 2007

When to trim fountain grass

We recently purchased a home in Las Cruces which has fountain grass and purple fountain grass. I have been unable to find any information on removing the dead grasses from previous years. At the Garden Stores I have received answers such as - "dig them up", leave them alone". I am completely confused and have not been able to find the info I am looking for in garden books - have bought four books which I have enjoyed but they were not helpful in regard to fountain grasses. Any info you can give me, or any suggestions as to where I might obtain this info would be very helpful.

Joan C.

Answer:

You can just leave them alone, but then the dead and old leaves remain. Grass plants with the old leaves are healthy, but don't look as good as they could. I prefer to remove the old growth in the late winter before new growth develops. You can cut the top now, but the grass will be less stressed if you wait until it is dormant. Fountain grass is a warm season grass that is dormant during the winter and begins growth after the coolest weather is past. You can trim the top any time from fall until growth resumes in the spring. I enjoy the dormant grass through the winter, so I delay until just before growth begins. Grasses have a wide variety of winter colors, shades of brown, and their billowing motion in the breezes (and winds) adds life to the dormant winter landscape.

Fountain grasses (and most other grasses) have a manner of growth that allows it to be cut back without harming the plant. The growing point (meristem) of the plant is in the crown, at the base of the plant. As long as you do not damage the crown, trimming the top should not harm the grass. This also removes the old leaves, so the fresh new growth is not concealed in the old (brown or gray) leaves.

Some fountain grasses (Pennisetum setaceum) are considered invasive and their use is discouraged. Other fountain grasses are not considered a problem. Be sure yours is not one that can escape cultivation and damage the native landscape. You can also consider many of the other ornamental grasses that add texture, motion, various summer and winter color to your landscape. Some of these grasses are also great attractants for birds and other wildlife.

Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email: desertblooms@nmsu.edu, office: 505-865-7340, ext. 113.

For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms and the NMSU Horticulture Publications page.

Send gardening questions to Southwest Yard and Garden - Attn: Dr. Marisa Thompson at desertblooms@nmsu.edu, or at the Desert Blooms Facebook.

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