Preparing Your Lawn for a Potential Drought

Last updated 5/1/00

HOME

Preparing Your Lawn for a

Potential Drought

Zac Reicher and Clark Throssell
Purdue University Turfgrass Specialists

AGRY-2000-01
May 1, 2000

As low moisture conditions continue in Indiana and long-range forecasts show little precipitation, it is time to start preparing for a potentially serious drought. It is always difficult to predict the summer weather, but with precipitation 11 or more inches below normal over the last year, it is conceivable that water shortages and irrigation restrictions could occur. Following are some common questions and answers to consider when preparing turf for a drought.

How long will turf survive without water?
Generally, turf can survive 5 to 8 weeks of dry conditions without substantial thinning or death. However, poor soils, traffic, excess heat, low mowing and/or scalping, and improper fertility (too much nitrogen fertilizer in spring, not enough in fall) reduces the survivability of turf during drought. Turf species will also affect drought survival, with warm season grasses like zoysia and bermudagrass surviving the longest without water, followed by the cool season grasses tall fescue, fine fescue, Kentucky bluegrass, and perennial ryegrass in that order.

What can be done NOW to improve drought tolerance of the turf?
Mowing. Mow as often as needed and at the upper end of the optimum range of mowing heights for the particular species. Frequent mowing reduces scalping. Scalping depletes energy reserves in the plant, reducing its ability to withstand and/or recover from drought stress.

Fertility. Heavy spring nitrogen fertilizer applications increase shoot growth at the expense of root growth and will also deplete energy reserves. If you must fertilize, use low rates of nitrogen (0.5-0.75 lbs N/1000 sq. ft.) every 4 to 8 weeks as needed to maintain health of the turf while limiting growth surges. Slow release N sources such as sulfur- or polymer-coated urea, urea formaldehyde, methylene diurea, dimethylene triurea or natural organic nitrogen will also limit growth surges. Though potassium is thought by some to encourage drought tolerance, it is not well documented and thus don’t overdo potassium fertilization.

Irrigation. Water deeply and infrequently, keeping the soil as dry as possible. Water thoroughly to wet the soil to the depth of the root zone and then don’t water again until areas of the turf turn a slight bluish-gray. Not only will this tend to encourage deeper rooting, it will also keep shoot growth at a minimum, conserving energy reserves. Additionally, anything that we can do now to conserve water should help to make more water available later. Water early in the morning (between 4 and 9 am) and avoid watering during the heat of the day because much of the water is lost to evaporation.

Aerification. Consider aggressive aerification to reduce soil compaction and improve rooting. Use the largest available hollow tines (not solid tines) and punch between 20 and 40 holes/sq. ft.

What can be done in the middle of summer to improve turf health and reduce drought damage?
Mowing. Often we will attempt to raise the mowing height during the summer to improve stress tolerance. Though this is advantageous because it increases photosynthetic area, it will also add extra stress to the root system by adding more leaf area to support. Since the root system needs 4 to 6 weeks to compensate for an increase in mowing height, you must set the mowing heights up well before stress occurs. You are better off starting out the year with mowing heights as high as possible rather than changing mid-year.

Fertility. Maintain a minimum fertility on irrigated turf to keep growth moderate. An application of a slow release fertilizer such as sulfur coated urea to dormant turf will encourage the turf to recover faster once irrigation or rains return.

Irrigation. Rank turf areas in the order of their need for irrigation and then irrigate accordingly. Obviously, the front lawn or main entry points would take priority on a lawn as well as other high traffic areas. Irrigate these areas deep and infrequently as described previously. During a drought, most tend to water more frequently with lower rates. This tends to encourage shallow rooting as well as potentially building up salts in the upper soil profile. It is better to water thoroughly, wetting the entire rootzone and flushing any salts past the rootzone, and then don’t water again until water stress is apparent. Lower priority areas could receive no irrigation, or maybe just "survival irrigation". Survival irrigation is applying Ľ to ˝ inch water every 4 weeks to rehydrate the grass crowns, but not cause the turf to green up.

Traffic control. Even minimum traffic damages drought-stressed turf, so it is best to eliminate or at least minimize traffic. Eliminate mowing on dry turf to minimize damage from wheel tracks.

Looking ahead to minimize damage from future droughts.
Experiencing one drought will prepare us to better handle the next drought. Inventory the turf during a drought, noting deficiencies in irrigation, soil, traffic management, or other areas that caused poor performance. Plan ahead for reseeding specific areas or the entire lawn in the fall. Tall fescue is probably the best lawn grass for surviving drought while still providing an attractive lawn. If you choose to irrigate your lawn in the future, consider installing an underground irrigation system because it is the most efficient way to irrigate a lawn while minimizing water use.

More information
Much more information is available on our web page including the following publications:

AY-3: Establishing Lawn Areas From Seed

AY-7: Irrigation Practices for Homelawns

AY-8: Mowing, Thatching, Aerifying, and Rolling Turf

AY-13: Lawn Improvement Programs

AY-22: Fertilizing Established Lawns

AY-25: Purchasing Quality Grass Seed for Your Lawn

AY-27: Maintenance Calendar for Indiana Lawns

Purdue University

Cooperative

Extension Service

West Lafayette