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Get your lawn ready for summer

Posted 4/29/2008

There are a few things you can do to help your lawn cope with the upcoming heat if you haven’t done so yet. First, lawn areas should be aerated in preparation for the heat. Aeration will help get the roots down deeper and improve your lawn’s ability to withstand drought. Actually this should have been done earlier; but if you haven’t done it, then it should be done now. Aeration is particularly needed if you see any standing water, or runoff on slopes or heavy traffic areas. Aeration can be done safely anytime of the year, while dethatching is best done in the late fall. Secondly, follow aeration with a fertilizer high in phosphorus and potassium. Robert Morris, Extension Horticulture Specialist, normally recommends a fertilizer high in nitrogen, low in phosphorus and moderate in potassium. But following aeration is a great time to get phosphorus into the root zone. And since phosphorus doesn’t move through the soil easily, it will help to apply it after aeration. Phosphorus also improves root growth, which is why you are aerating now. The potassium is to help in drought stress. If you haven’t fertilized for quite awhile, then give a high nitrogen fertilizer as well.

The last thing you want to do in preparing for the heat is to get your mowing height up. Mow at two and one-half inches or higher for fescue lawns. When the grass grows one-third higher, mow again. If one-half or more of the grass blade is removed during mowing, too much of the grass blade is removed and stems are exposed. This stresses the plant by initiating rapid regrowth of leaves and a drastic reduction of the root system. Maintaining height helps hold in moisture and shades roots. Mowing higher will encourage the roots of the grass to go deeper, particularly if it’s done after aerating and fertilizing. A closer-cut turf results in shorter roots that are susceptible to drying out during the heat and to disease. Turf should have a finished, tailored look. This effect is not due to the height of the cut but rather the evenness of the cut and the sharpness of the mower blades. Also, leave clippings on the lawn. They will decompose, releasing nitrogen back into the soil. Clippings do not lead to thatch buildup as once thought.

Irrigation problems are the number one reason for brown lawn spots. The irrigation system must be designed, installed and maintained properly. Irrigation sprinkler heads must have head-to-head coverage (water from sprinkler heads should overlap enough to reach neighboring heads in the vicinity). This is a necessity. Sprinkler heads should have nozzles that are all the same type, not a mixture of several types on the same system, so that they put the same amount of water down on the lawn during an irrigation cycle. Mix and match heads may not do this. Mix and match heads in a lawn will waste water and affect your water bill. You can test the uniformity of your sprinklers by placing small containers like tuna cans in several locations; then run the normal water cycle and see how much water is in each can. This can help identify where you might want to add a sprinkler head or make adjustments for proper coverage.

The general guidelines for watering tall fescue for June and July are to water early in the morning between 2:00 and 5:00 a.m. 7 days a week for 12 minutes per day. This recommendation is for flat lawns where there is no runoff. If you have slopes in your lawn, you need to split the watering time into at least two run times. If you have slopes and water runs off before the recommended time is up, set your timer to come on at 2:00 a.m. to run about 6 minutes on each station. Allow enough time for all stations to run plus a few minutes extra; then set the timer to run each station again. Using this method, if you have five stations (valves) you would set the first start time at 2:00 a.m., and the second start time at 2:45 a.m. The first time you run a program like the two different 6-minute times, you should try it out in the daytime to see if this takes care of the runoff problem. If the 15-minute time between station run times is not enough to prevent runoff, you can allow a half hour to one hour in between start times. If you still have runoff, divide the total run time into three 4-minutes runs. If you have rotating sprinklers, water for 12 minutes each watering. Bermudagrass requires about one-third less water than fescue.

If you water grass a few minutes in the morning and a few minutes at night, you are encouraging shallow root growth. The roots will only go as deep as the water soaks into the soil. Applying all the water needed at one time or in two or more shorter sessions close together will allow the water to soak into the soil deeper and your grass roots will grow deeper. Deep roots will help your lawn survive our dry, hot weather much better and if you should happen to have irrigation system problems, it will not die as quickly. Call University of Nevada Cooperative Extension at 702-346-7215 or 397-2604 for more information on watering plants, or visit the Southern Nevada Water Authority web site at and click on the watering guide picture.

The University of Nevada Cooperative Extension is an outreach arm of the University that extends unbiased, research-based knowledge from the University of Nevada-and other land-grant universities-to local communities. Educational programs are developed based on local needs, often in partnership with other agencies and volunteers. For more information about the University of Nevada Cooperative Extension, please visit the website at or call (702) 397-2604 or 346-7215.

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