Facts and Advice on Turf Survival in Drought

There are many questions about turf survival in drought with the on-going drought in most parts of the state. Though we understand many of the mechanisms of turf survival in drought, it’s hard to duplicate all of the potential situations on research plots across the country and it’s difficult to give definite “black and white” recommendations for every given situation. Following are facts supported by research but also some statements that are supported by experience and anecdotal evidence where appropriate.

Facts

•  Though turfgrasses perform best with enough regular irrigation during the summer to keep them green and growing, they are very capable of surviving without rain or irrigation.
   Turfgrasses perform much better under slightly dry conditions than under wet or saturated conditions. 
   Turfgrass dormancy (brown turf) is a survival mechanisms allowing survival up to 5-8 weeks without irrigation/precipitation without significant thinning upon recovery from dormancy. This would be under ideal conditions of no regular traffic, good soil, moderate temperatures, no shade, minimum thatch, etc. However, survival is affected by species, age, shade, maintenance (low mowing and/or scalping, too much nitrogen fertilizer in spring, not enough in fall), traffic, heat, etc., etc.; so optimum survival may not occur on your particular area.

Deciding to water or not

•  Many turf areas should be allowed to go dormant, especially in the Indianapolis area where water supplies or pressure are limiting.
   Turfgrasses that are trafficked during drought conditions (golf courses, athletic fields, etc) MUST be irrigated regularly to maintain performance and prevent widespread turf damage.
   Turf areas established this spring or late last fall should be irrigated because they have not developed extensive root systems.

Advice if you choose to water

•  Since all turfgrasses perform best on the dry side, water thoroughly to wet the soil to the depth of the deepest root (maybe 2-4“ into the soil) and then don’t water again until you see the turf turning a bluish-gray in the heat of the afternoon (the first sign of drought stress).
   Try to expand the number of days between irrigation cycles, you’ll likely be surprised on how long the turf can go without signs of drought stress.
   Consider purchasing a rain sensor for your automatic irrigation system to prevent watering during or after rain events. Also use the irrigation budgeting features of your irrigation system. 
   Check your irrigation system for improperly aimed sprinklers, non-turning sprinklers, evenness of distribution, etc. This is true for automatic as well as hose-end sprinklers. This will improve the efficiency of irrigation and cut down on water use.
   Aerify regularly with hollow tines to improve water penetration into the soil.
   Water between 5:00 and 8:00 am to improve efficiency because of less evaporation and wind distortion. Irrigating early in the day does not favor disease. The second best time is between 7:00 and 10:00 pm, but this tends to favor diseases.

Advice if you choose not to water

•  Stay off the turf! Limit traffic (including mowing) to minimize crushing of the turfgrass leaves and crowns.
   Water once every 4 weeks with ½ inch of water to keep turf plant crowns hydrated. This amount of water should not green up the turf, but it will increase its long-term survival.
   Avoid the temptation to apply herbicides even though weedy species may become more obvious in a dormant (brown) lawn. Herbicides are ineffective on drought-stressed weeds and can be damaging on drought-stressed turf.
   Professionals might consider applying 0.75 lbs N/1000 ft2 with a 60-75% slow release N source. This should help to speed recovery when rains resume.
   Turf should recover in 1-2 weeks after significant rainfall returns. 
   Aggressive fall fertilization may be needed after the rains return and turf recovers. Applications of 1.0 lb N/1000 ft2 in Sep, Oct, and Nov. can help thinned turf fill-in quickly.
   Overseeding may also be necessary this fall after the turf recovers. Overseed if baseball-sized patches are open in perennial ryegrass or softball-sized patches in Kentucky bluegrass Use our web page at http://www.agry.purdue.edu/turf/tool/index.html to help identify grasses.