Watering lawns under water-conserving restrictions

Watering restrictions have recently been imposed in Las Cruces. I can only water 3 days a week and I am concerned that I won't be able to water my fescue lawn adequately in the hot summer months. I have to water every day to have a nice lawn and landscape, and I don't want it to go bad, but I don't have the money to convert to a desert landscape. What should I do?

This is becoming a common problem in the Southwest as our population and water demand grows. At the same time, we are becoming more aware of our limited water resources. Cities are reacting by passing ordinances intended to limit water use, especially in the landscape. Citizens with established landscapes are especially concerned and, as you stated, not all citizens can convert their landscape to a more water conservative landscape. I found your term "desert landscape" interesting, because it could refer to a xeriscape with abundant and attractive plant life, or it could refer to the "rockscapes" or so-called "Southwestern landscapes" which are appearing in response to calls for water conservation. I will address that later. Let's return to your specific question regarding what you can do.

If conversion to xeriscape is not financially possible, you can increase the efficiency with which you use water. Many people in New Mexico think they must irrigate daily in the hottest part of the summer. This is not always true. A properly installed and maintained fescue lawn can be irrigated every three days or less. A professional turf farmer in Southern New Mexico who grows fescue on sandy soil irrigates every three days and has attractive grass. How does he do that? The soil was prepared by rototilling deeply so that the roots could reach at least a foot deep. While rototilling, organic matter was added to the soil to increase the waterholding capacity of the soil. The grass is then properly maintained, mowing when needed, not cutting more than one-third of the leaf blade at each mowing, not over fertilizing in the heat of the summer, and not over irrigating in the heat of the summer. Fescue is a cool-season grass and should be allowed to become dormant in the summer. That means no fertilization to encourage growth when it is resting and irrigation sufficient to only keep the grass alive, not rapidly growing. By not over irrigating and fertilizing when heat stress is at its maximum, the grass is less subject to diseases.

If the soil was not properly prepared initially, it may not be possible to increase irrigation efficiency. Aeration to remove plugs of soil followed by top-dressing with compost may help. In some situations it may be necessary to rework the soil and reseed or sod. At this time consider whether a cool-season grass or warm-season grass is more desirable. Your county Extension agent can advise you as to the appropriate cool- or warm-season grasses to use.

It is also wise to see how efficient your irrigation system applies water to the lawn. Most older and, unfortunately, some new systems are very inefficient. To keep the lawn looking good, large areas are overwatered by inefficient systems. A certified irrigation auditor can help you determine how efficiently your system works. If it is inefficient, you may find that it is economical to replace it.

Reworking the lawn will require money, but continuing to apply water inefficiently will also increase your monthly expenses as water rates increase. Fines for "illegal" watering can also become expensive.

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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