Watering the lawn in winter
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Issue: November 8, 2008

Watering the lawn in winter.

Question:

Should I water my grass during the winter here in Las Cruces? I have conflicting views from the folks who live around me. Thanks in advance for any light you can shed on this for me.

Earl R.

Answer:

Some grasses may be brown during the winter, but they are still alive and need some moisture. Natural precipitation is usually not enough to supply even the reduced water needs of grasses during the winter in New Mexico, so some irrigation is usually necessary. Dr. Bernd Leinauer, NMSU Extension Turfgrass Specialist, has been conducting research regarding water use by grasses in New Mexico. Based on his research, Dr. Leinauer makes the following recommendations.

Lawn irrigation throughout the year (regardless of whether it is summer or winter) should be based on a turf's actual water requirement, which is determined from its water loss or ET (evapotranspiration). Knowledge of the type of grass (warm season vs. cool season) and of the irrigation system's water delivery rate is necessary to best use ET data for irrigation scheduling and to most efficiently irrigate your lawn. NMSU's Extension Service offers irrigation workshops on how to irrigate lawns based on an irrigation system's performance and on ET information available on the Internet.

NMSU operates a state wide weather station network which is accessible through the Internet and provides daily ET values. Winter ET rates (Nov - Feb) for cool season grasses (such as Kentucky bluegrass or tall fescue) in Las Cruces can be between 0.02" to 0.15" (daily) or between 2" and 3.5" (monthly). The lower end represents values for December and January, the higher end for November and February. Because of the lower day temperatures, ET rates for Albuquerque should be about 10 to 20% lower than for Las Cruces. Further north, the percentage of ET can be reduced even more. Warm season grasses (such as bermudagrass or buffalograss) are usually dormant during the winter and therefore do not need to be irrigated on a regular basis.

It is my experience that many homeowners who irrigate their lawns have no information as to the exact delivery rate (inches per minute of run time) of their irrigation system. There are a large number of sprinkler types and their delivery rate varies depending on nozzles, water flow rate and pressure. To answer your question without proper knowledge of your irrigation system's performance, I would recommend irrigating your cool-season lawn once a week in November and February, but only once every other week in December and January. Warm season grasses can be irrigated once a month to enjoy an earlier green-up compared to no irrigation during the winter. These recommendations are based on a very dry winter, without precipitation. If there is enough snow and/or rain during the winter, you may get away without any irrigation.

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.