Managing Lawns During a Drought
Widespread drought conditions across Ohio this summer has led to unirrigated lawns experiencing stress from water deficit and turning brown in color. Many of these lawns have entered a dormancy period to survive under extreme water deficit, while areas of the lawn in shade may still be retaining green color. In the case of dormancy, the turfgrass is not dead and should begin recovering after receiving rainfall or irrigation.
What can I do if my lawn is dormant?
Irrigate
If your lawn is dormant and you want green, growing turfgrass again, water is necessary. This is easier said than done, as irrigation can be expensive and time consuming. However, if you decide to irrigate, consider a sprinkler type that applies water at a low rate. Since soils are currently very dry, water will not infiltrate the soil if applied in large amounts. Instead, the water will run off into areas downslope of your lawn. We typically recommend irrigating in the morning hours (~5-9 AM); however, when recovering from drought stress, irrigate when it is most convenient for you. Sure, evaporation is more likely at 2 PM than 7 AM, but some water is better than no water in this situation. Once you start irrigating your lawn, it's important to maintain a regular watering schedule to avoid further stress.
Stop Mowing
When a lawn is under drought stress, mowing provides another unnecessary stress to turfgrass. The physical process of cutting the turfgrass blades is considered a stress, in addition to the extra foot and/or tire traffic. Avoid mowing dormant and drought stressed lawns.
Pause Fertilization & Weed Control
We have entered the season for fertilizing the cool-season turfgrasses typical for Ohio lawns, as most of the yearly nitrogen fertilization should be applied in September-October. This application is important for lawns to recover from summer stress. Unless you have an actively growing lawn, pause fertilization until turfgrass begin to recover from drought. If drought stress conditions persist into the winter, consider skipping this year’s fall fertilizer application. Turfgrass plants must absorb fertilizer in a dissolved form. This requires water to be present for the fertilizer to dissolve and be taken up by the plant. However, dormant turfgrass plants do not actively absorb water, limiting their ability to utilize fertilizer. Fertilizer applied without regular irrigation will remain on the surface until rain occurs.
Most herbicide labels recommend applications to actively growing weeds, as herbicides become less effective when weeds are under drought stress. Drought stressed turfgrass is also more prone to injury from herbicides, reducing the selectivity of selective herbicides. Also, if you are planning to renovate your lawn this fall and want to eradicate the existing turfgrass – nonselective herbicides (e.g., glyphosate) are only effective when applied to actively growing turf and weeds (Turfgrass Establishment Series – Nonselective Weed Control).
What about seeding this fall?
The fall is also the ideal time to plant turfgrass seed, whether that is overseeding an existing stand or completely renovating a lawn. The current drought conditions make establishing turfgrass from seed difficult. Water is necessary for turfgrass seed to germinate, but you can still plant seed during these drought conditions. The seed will not begin the germination process until it begins to absorb water (i.e., imbibition). Once this process begins, the germination process is irreversible. Therefore, once seed begins receiving water, it must maintain sufficient moisture throughout establishment (Turfgrass Establishment Series – Irrigation). When planting seed, some methods can be implemented to maximize seed-to-soil contact, retaining moisture and limiting seed displacement (Turfgrass Establishment Series – Planting & Mulching).
Turfgrass species and cultivar selection is important when planning for future drought events. In general, tall fescue is more drought resistant than Kentucky bluegrass. Additionally, cultivars within species vary in their drought resistant. For example, some Kentucky bluegrass cultivars are more drought resistant than others. Groups such as the Turfgrass Water Conservation Alliance and the Alliance for Low Input Sustainable Turf certify cultivars that have demonstrated improved quality under reduced inputs. When selecting a seed blend or mix, ensure drought resistant cultivars are included.