Thatch is the accumulation of above-soil runners, propagated by the grass. This layer should be about 1/2″ ( 1.25cm) on a healthy lawn, and kept in balance by natural decomposition, earthworms and microorganisms. Too much thatch prevents water and nutrients from reaching the grass roots. You can reduce thatch with a steel rake, or by renting a de-thatcher which does a more thorough job.
Reduce or eliminate nitrogen fertilizer and increase potassium fertilizer.
Avoid using herbicides
Avoid the temptation to apply herbicides even though weedy species become more obvious in a dormant lawn. Herbicides are ineffective on drought-stressed weeds and can be damaging on drought-stressed lawns.
Water deeply but not too often
Thorough watering encourages your lawn to develop deep root systems which make the lawn hardier and more drought-resistant. Let the lawn dry out before re-watering; as a rule of thumb, the color should dull and footprints should stay compressed for more than a few seconds. When watering, put a cup in the sprinkler zone; it should get at least one inch (2.5cm) water.
The best time for watering is early morning – less water will be lost to evaporation. Ideally, it’s better to water the first half-inch or so, then wait for an hour or two before watering the second half-inch.
Keep mower blades sharp
A dull blade makes a tear rather than a clean cut, which requires more of the plant’s reserves to heal the wound. This reduces the grass plant’s vitality which is needed to sustain the grass through the stresses of a drought.
Mow often, but not too short
Mow the lawn often enough so that you don’t cut off more than one-third of the grass at any one time. Set the cutting height so the grass is not cut too short. If mowed too closely, surface roots become exposed and root growth is slowed. This reduces the lawn’s tolerance to heat and drought. Most turf grass species are healthiest when kept between 2.5 and 3.5″ tall.
Leave clippings on the lawn
The clippings act as mulch, helping to reduce water loss due to evaporation. As long as the clippings are thinly spread, and not clumped, they will not contribute significantly to thatch buildup.
INTRODUCE LOW-MAINTENANCE DROUGHT-RESISTANT LAWN SEED TO YOUR LAWN
New “eco-lawn” grass seed is available which requires less water to grow, and which grows very slowly once it reaches heights of 3 – 4″, thus reducing the frequency of mowing. The seed can be sprinkled on bare spots and thin areas, and can be interplanted with existing lawns to gradually transition your lawn to a hardier, low-maintenance lawn. (At our home, we planted an eco-lawn this spring and are very pleased with the results. Even during this dry spell it’s still green and lush, while the old lawn in front of the house is brown and dry.)
Save and recycle all available water
You can collect and store rainwater from your roof by installing a rain barrel. Water stored in a rain barrel does not have enough pressure to run a sprinkler, but you can connect the hose to the spigot on the rain barrel and use this to hand water areas which you want to keep green.
During a drought or when water-use restrictions are in effect:
You can conserve water by temporarily withholding water from the lawn and inducing summer dormancy. The objective is to supply just enough water to keep the lawn alive until conditions improve. Although the lawn will go brown, the crown, rhizomes and roots may survive for 4 to 6 weeks without watering. In addition, the following steps will help:
Raise the mowing height 25 percent or more
Letting the grass grow a bit taller will increase the shading of surface roots and help retain surface moisture.
High fertility before or during a drought can promote injury to the grass and reduce root mass. Nitrogen rates should be kept low; feed almost as much potassium. This will produce healthy and tough tissues. If darker color is required, don’t apply more nitrogen; consider spraying foliar iron instead.
Reduce foot traffic on the lawn
As the top layer of soil dries, damage from compaction increases. Aeration is reduced and the root system has decreased access to available moisture.
Identify the ‘hot spots’ on your lawn for more focused watering
Areas near buildings and other heat-reflecting surfaces will be hotter and drier, and will require more water than cooler areas, such as spots which are shaded by trees or large shrubs. Once you identify the hot zones you can more efficiently focus the watering.
Consider replacing some turf with drought resistant trees/shrubs/flowers
In areas where a drought is extended, and likely to recur in future years, look to water-saving (and maintenance-saving) landscape alternatives. Plant native perennials, use xeriscape techniques, learn about ground covers which do well in your region, and use mulch around perennial shrubs and trees to further conserve water.
Turf should recover in 1-2 weeks after significant rainfall returns. Overseeding may also be necessary in the fall after the turf recovers.