IRRIGATING LAWNS

Just remember one simple point: Do not regularly water established cool season grasses during the summer unless you plan to do so all season. Many lawns are lost by discontinuing irrigation in midsummer.

How's your lawn looked this spring? Spring is usually a great season for cool season lawns. Now there are some decisions to be made as summer weather approaches.

The tall fescue lawns have been lush and green all spring and now a major question must be asked. Should the lawn be irrigated this summer to help it through the stressful periods? If the answer is yes, there are few points to keep in mind.

Improper irrigation of lawns results in waste, added cost, and unhealthy plants. Water should be applied only when lawns show signs of moisture stress:

• dark bluish gray colored leaves
• footprints that remain some time after walking
• wilted, folded, or curled leaves

These are indications that it is time to water. Delay in watering at first signs of wilt can result in permanent damage unless the turf is being allowed to go dormant. Do Not Water/Irrigate the lawn half way into summer and then stop irrigating. This practice will cause permanent damage to the grass. Cool season lawns, like tall fescue, will by nature of the plant go dormant during those hot dry periods as a way of protecting itself. Irrigating these grasses through these periods keeps them green and active.

Early morning is the preferred time to water because it reduces the risk of disease, water loss through evaporation, and improper water distribution. Also, the demand for water by industry and municipalities is usually low at this time of day. Many irrigation systems are set to come on just before sunrise.

Established lawns should be watered to a depth of 6 to 8 inches to encourage the roots to remain deeper in the soil. Usually, 1 inch of water per week is adequate. The 1 inch of water should be applied once every 5 to 7 days depending on the weather. A rain gauge can be used to determine how much water is being delivered in a given period of time. Clay soils are dense soils types and may accept the water slowly, thus water should be measured to prevent wasteful runoff. Water clay soils until runoff is about to occur; wait 30 minutes for the water to be absorbed; and rewater the area until the desired amount is achieved. Few lawns established on clay soils can absorb more than 1/2 inch of water per hour. Remember to adjust any automatic irrigation system to supplement rainfall so that the lawn is not overwatered.

Certain precautions should be taken if you have chosen not to irrigate throughout the summer. Slowly, ease a lush, actively growing lawn into dormancy. This can be accomplished by:

• deep and infrequent watering
• mowing high
• do not overfertilize with nitrogen.

In the absence of rain, water dormant lawns every three weeks to prevent turf loss from heat and drying. Brown, withered leaves are normal signs of dormancy, don't be alarmed by them. Turfgrasses are able to withstand prolonged drought periods.

Click here for Water Wise Lawn Irrigation Information

Mark Blevins , Horticulture Agent

http://www.ces.ncsu.edu/gaston/