Often lawns are made up of several different cultivars or species of grass so a drought stressed lawn may also have a patchy appearance (Figure 1). Individual grass plants can recover and green up again, once the plants get sufficient water.
The obvious answer to drought stress on lawns is to apply water. Deep, infrequent watering to the depth of the root system is the ideal situation. This should be done when lawns show the first signs of drought stress, such as wilting, darkening color, and footprints remaining after walking across the lawn.
If we struggle in this exceptional heat, then surely our grass does, too! So how long does it take for grass to come back to life after excessive heat? It can take up to 6 weeks for your grass to recover, with germination taking place between 2-3 weeks after a drought.
A dormant lawn is not a dead lawn. With the right care, your lawn can survive a drought and come back lush and green as soon as the water comes back.
These grasses naturally go dormant during periods of hot, dry weather, essentially stopping active growth. Dormant grass will often look brown and dead, but the roots and crowns of the plants are still alive and will be ready to resume growth as soon as growing conditions improve.
It's no fun when you break out your shorts and sunscreen to enjoy your backyard and discover prickly, brown grass has overtaken your lawn. Thankfully, your dead grass will probably grow back with the proper care if you've caught the problem quickly (within about 3-5 weeks).
Drought stress is most noticeable on slopes and lawns established on shallow or poor soil, Patton said. "In order to keep your lawn green during hot and dry periods, at least 1 inch of water will need to be applied weekly," Patton said.
Fertilizer & Herbicide Treatments
Avoid applying fertilizer to a drought stressed lawn – it will not cause the grass to green up and can actually increase overall stress. Wait until mid- to late-August to make that fall application.
You'll often see grass looking a little bluish-purple/gray instead of bright green when it's starting to get stressed. Usually this goes hand in hand with the footprints in the lawn symptom. A golden yellow or brown lawn.
If you choose to fertilize, look for a fertilizer with a primarily slow-release nitrogen and phophorus source that will not promote rapid growth. Look for a fertilizer with a high potassium level (the third number on the bag) as this can help to enhance drought tolerance.
Increase your watering time per zone by about 50 percent. You shouldn't have to water more than 6 or 7 days a week. However, if your lawn still isn't as green as you'd like, simply repeat your watering schedule immediately following the first run-through.
However, if your lawn is heat-stressed, avoid fertilizer products. Lawn fertilizer on a heat-stressed lawn can have the opposite effect and can cause further damage to an already sensitive grass area.
After they slow down, they will begin to show signs of stress. This could be certain areas starting to brown out and look dead. That's the natural habit of our grasses, they will go dormant (not dead!) during times of heat or drought stress. This is where watering is crucial.
Restrict Mowing.
When rain is plenty, it's best to keep your grass short. But in drought, let the grass grow a bit longer. Longer blades or grass means a deeper root system; deeper roots means the grass can get to water deeper within the soil.
The best method is to use sprinklers which mimic the slow, soaking nature of a light rain. The best time to water is in the early morning, just after the sun rises. At this time of day, it is still cool and the water won't evaporate too quickly. Some homeowners panic at the sight of drought stress and overdo it.
Longer grass will keep the soil cooler and that means you're not going to use as much water. To keep your lawn as healthy as possible during a drought,” concludes Mann, “longer is better.”
The good news is that despite their delicate structure and appearance, grasses are surprisingly resilient. Most types of grass can survive extended periods of drought, and although they may look dead—visibly brown, dry and limp—they're often only dormant, awaiting the next rainstorm.
Fertilizing a dormant lawn will not harm it. However, the turfgrass may not receive the full benefit of the fertilizer application. If a granular fertilizer remains on the soil surface because of a lack of rain, some of the material may actually volatilize into the air.
Water weekly, not daily. Over a growing season, you can train your yard to be less thirsty by watering less frequently but more deeply, to encourage deeper root penetration into the soil. Shallow roots need much more frequent irrigation. Yes, plants will wilt, leaves will drop, but the plants will survive.
Water your lawn 2-3 times a week during a drought, early in the morning to minimize evaporation. Don't water in the evening or overnight, as this increases the likelihood of attracting disease or pests. If your lawn has not begun to go dormant, you should see green coloration with regular watering.
Without moisture, pasture growth slows and pastures may even become dormant. Grazing (or mowing) below 3″, and excessive hoof traffic, can accelerate drought effects and slow regrowth once it rains.
What looks dead should be green again by late spring or early summer. Lawns in cooler climates are a little different. Cool-season grasses may turn brown and look dead in summer if they're forced into dormancy due to heat and drought.
Lawn aeration is a great way to help revive brown “dead” grass; poking holes in a lawn will grant the roots unencumbered access to oxygen. Professional lawn-care services may offer this service in the spring to help revive dormant winter grass in time for the summer.