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Shutting Off Water to Bluegrass Lawns: a Legitimate Water Conservation Possibility

By Carl Wilson, Colorado State Cooperative Extension, Horticulturist, Denver County

Water restrictions in some Colorado cities have limited the water available to irrigate lawns and raised questions about what this means for long-term lawn survival.

Plant research at Colorado State University and elsewhere shows bluegrass has excellent drought dormancy abilities and does not die if it turns brown. Bluegrass can remain brown and dormant for months and then resume growth and turn green when water is again applied.

In water-short situations, it is generally better to cut off water completely and allow bluegrass to enter drought dormancy than supply only a small portion of what is needed for healthy growth. Water-stressed lawns are more subject to damage from disease and insect attack than lawns that are watered to meet plant needs or drought dormant ones.

City-requested water reductions of 25 per cent or more will be difficult to achieve unless outdoor watering practices are altered. Over 50 per cent of annual residential water use goes to landscape irrigation leaving only 25 percent for indoor use if all 25 percent is cut indoors. Studies show that many Colorado lawns have been irrigated with 30 to 40 percent more water than is needed for healthy turf growth. Potential savings in these situations are high by simply watering to better meet plant demands.

Beyond applying water only to meet plant needs and tuning up sprinkler systems, another viable choice is turning off sprinkler zones to lawns. Viable candidates include outlying and lightly used turf areas. Another is turf in narrow strips between the sidewalk and street where trees are not present.

Narrow strips are difficult to irrigate with either automatic or hand-set sprinklers. Water always ends up on the pavement and is wasted. Keeping residential lawns near the house green while drying up these narrow sidewalk strips may be an option for many people.

Note that if street trees in city situations have little additional lawn area beyond the narrow sidewalk strip to forage for water, cutting the water supply could cause tree damage. Well-established trees and shrubs growing within residential lawns are generally healthier and tolerate some period of drought. Recently planted trees and shrubs should be hand watered if lawn irrigation is eliminated.

What about the drought dormancy abilities of other grass types? Turf-type tall fescue lawns show little drought dormancy and will thin if stressed for moisture for more than a few weeks. Bermudagrass, grown mostly in southeastern Colorado, and buffalograss are similar to bluegrass in their well-developed drought dormancy abilities.

Photo: Judy Sedbrook

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Date last revised: 01/05/2010