Issue: December 15, 2007

Removing grass to make a rock landscape

I want to change to desert (rock) landscaping. What is the best method? One landscaper said that either he would put plastic over the existing grass, or the he would lift the grass. It appears to me that lifting the grass would be the most effective. Also is there a preferred time of year to do this?

Anna R.
Roswell, NM

Answer:

There is a third option- the use of a non-selective herbicide. The method (or combination of methods) to use depends on which grass you are removing and your ultimate purpose. Covering the grass with black plastic will kill the grass under it by excluding light, oxygen, and water. Lifting the grass may also effectively remove the grass from the landscape. However, if the grass is bermudagrass, it may be more difficult. It is difficult to eliminate bermudagrass by digging (lifting) it unless you dig very deeply. The plastic may work in this instance, except near the edges. Bermudagrass, with its sharp, bamboo-like, sprouts may pierce the plastic and overcome that barrier as well. Even treatment with an herbicide may take several treatments.

Use of an herbicide combined with one of the other treatments may eliminate the grass more quickly. This is especially true if the grass is bluegrass or fescue. Some people prefer not to use the herbicide, and it is possible to succeed without herbicide. However, the project will take longer and will require greater vigilance. Each time the grass begins to regrow from sprouts left in the soil, it must be removed.

I should also caution you about the use of plastic. Solid, impermeable plastic is effective, but it may create problems for plants introduced into the landscape later and for plants (trees and shrubs growing nearby). This is because the plastic reduces oxygen levels (needed by plant roots) and moisture under the plastic. Nearby trees and shrubs will probably have roots growing in the area you are treating.

If you intend to have a landscape with only rock and no plants, please consider that this landscape will be very hot in the summer. Rock landscapes remain hot well into the night. As a result, cooling costs will increase in a home or business surrounded by a rock landscape. Rock-only landscapes have been installed as a "low maintenance" form of landscaping. Many homeowners are surprised by the maintenance involved if leaves blow in from surrounding landscapes. These landscapes do not prevent weeds. Dust blown by the wind settles between the rocks and above the plastic. During rainy periods, weed seeds (blown in along with the dust) sprout in the layer of dust below the rocks. These weeds then create an unattractive landscape.

Use of porous, weed-barrier fabrics offer an appropriate compromise to the use of solid plastic. The weed barriers are porous to allow water and oxygen to penetrate, but block sunlight and greatly reduce the growth of weeds. However, even these products have problems with weeds sprouting in the dust that accumulates above the barrier.

For more gardening information, visit the NMSU Extension publications World Wide Web site at http://www.cahe.nmsu.edu/pubs/_h.

Send your gardening questions to:
Yard and Garden, ATTN: Dr. Curtis Smith
NMSU Cooperative Extension Service
9301 Indian School Road, NE, Suite 112
Albuquerque, NM 87112

Curtis W. Smith, Ph.D., is an Extension Horticulture Specialist with New Mexico State University's Cooperative Extension Service. New Mexico State University is an equal opportunity/affirmative action employer and educator.