Should you mow your lawn during a drought? What Wisconsin experts recommend

EAU CLAIRE, Wis. (WEAU) - Western Wisconsin desperately needs rain, but if you’re looking at your lawn this weekend and wondering whether firing up the mower will help or hurt, experts say the answer may be as simple as taking a walk.

If your footprints remain visible in the grass for more than about 10 minutes, UW-Madison Division of Extension says your lawn is showing signs of drought stress.

And you probably shouldn’t mow it.

That’s one of several recommendations from Wisconsin lawn experts as drought conditions expand across the state and rainfall remains well below normal in Eau Claire.

Through Aug. 13, Eau Claire received just 0.28 inches of precipitation this month, compared with a normal 1.79 inches.

So what does that mean for your lawn?

Should you mow during a drought?

First, don’t mow simply because it’s Saturday.

UW-Madison Extension recommends mowing based on how quickly the grass is growing rather than following a weekly schedule.

During cool, wet periods, that could mean mowing more than once a week. During dry summer weather, it may mean waiting two weeks or longer between mowings.

More importantly, Extension recommends avoiding mowing altogether when grass is showing signs of drought stress.

Mowing creates wounds in grass blades through which moisture can escape. Under normal conditions, that’s not a significant problem. During a drought, however, UW Extension says mowing stressed grass can cause it to turn brown more quickly.

There is an easy way to check.

Walk across the lawn.

Grass blades that are adequately hydrated should spring back. If your footprints remain visible for more than about 10 minutes, UW Extension says the grass is drought-stressed.

Other warning signs include grass developing a bluish color or blades that remain flattened after being stepped on.

If that’s happening, leave the mower in the garage.

UW-Madison Extension: Mowing Can Make or Break Lawns.

Does cutting grass shorter mean it needs less water?

It may sound logical: Less grass must mean the plant needs less water.

UW-Madison Extension says that’s not how it works.

For the cool-season grasses commonly found in Wisconsin lawns, cutting grass too short can actually make it less tolerant of drought.

Extension recommends maintaining grass at about 3 inches and says a height of 3 to 4 inches can help lawns withstand dry conditions.

Taller grass develops deeper roots, giving the plant access to more moisture in the soil. It also shades the soil and dries out more slowly.

UW Extension says common Wisconsin lawn grasses, including Kentucky bluegrass, perennial ryegrass, and fine fescues, can suffer when they are cut too short.

During summer, Extension says 3 inches should be considered the minimum mowing height and suggests homeowners consider going even higher when rainfall is lacking.

UW-Madison Extension: Watering Your Lawn

Don’t give your lawn a drastic haircut

There’s another rule to remember when you do mow: Don’t remove more than one-third of the grass blade at a time.

For example, if you want to maintain a lawn at 3 inches, don’t wait until the grass reaches 6 inches and then cut it back to 3.

UW Extension recommends adjusting mowing frequency to grass growth so no more than one-third of the leaf is removed during a single mowing.

Leaving grass clippings behind is also OK.

Extension says clippings will filter back into the lawn and decompose rather than causing thatch. The clippings also return nutrients, including nitrogen, to the soil.

My lawn is brown. Is it dead?

Not necessarily.

One of the more important things to understand about Wisconsin lawns is that brown grass can still be alive.

Kentucky bluegrass, the most common lawn grass in Wisconsin, can enter what is called summer dormancy during drought.

The grass allows its leaves to die and turn straw-colored while keeping the crown — the growing point near the soil surface — alive.

UW Extension says Kentucky bluegrass can survive in that dormant condition for two to three months. When sufficient moisture returns to the soil, the crown can begin producing new leaves and the lawn can turn green again.

Prolonged drought combined with excessive heat can eventually kill grass, however.

Should you water a brown lawn?

Homeowners essentially have a choice before a lawn becomes dormant: water sufficiently to maintain active growth or allow established grass to go dormant.

UW Extension says lawns that are being maintained green generally need about 1 inch of water per week from rainfall and irrigation combined, although the amount can vary with weather and soil conditions.

If you water, experts recommend doing it less frequently but thoroughly enough for moisture to reach the grass roots.

Frequent, light watering can encourage shallow root growth, making grass more susceptible to drought. It can also contribute to disease and weed problems.

Early morning is generally the best time to water because less water is lost to evaporation and grass blades can dry during the day.

But once an established lawn has already turned brown and gone dormant because of dry weather, UW Extension advises against using large amounts of water to make it green again while summer heat continues. That process can stress the grass.

During a prolonged drought, Extension says a small amount of water about every two weeks can be used to keep the grass crowns hydrated.

Local watering restrictions should always take precedence over general lawn-care recommendations.

Menomonie has had a full lawn irrigation ban in place since July after high water demand contributed to a low-pressure event in the city’s municipal water system. The City Council is considering extending that ban through Oct. 31.

Don’t fertilize your way out of a drought

This is also probably not the time to reach for the fertilizer.

UW Extension does not recommend nitrogen fertilization during drought conditions.

Nitrogen encourages grass to grow faster. Faster-growing grass requires more water — exactly what a drought-stressed lawn doesn’t need.

For Wisconsin lawns, Extension says around Labor Day is a key time for nitrogen fertilization.

The same general advice applies to many herbicides. Extension recommends waiting until fall for broadleaf weed control because weeds can be less susceptible to herbicides during hot weather, while stressed lawn grasses can potentially be damaged.

The bottom line: Let the grass tell you what it needs

For homeowners trying to decide what to do this weekend, the simplest advice may be to stop looking at the calendar and start looking at the grass.

UW-Madison Extension: Summer Lawn Care Strategies

If the lawn is growing normally and isn’t showing drought stress, mow it high and remove no more than one-third of the blade.

If footprints remain visible, the grass has stopped growing, or the lawn is already brown and dormant, mowing may do more harm than good.

And a brown lawn isn’t necessarily a dead lawn.

Sometimes during a Wisconsin drought, the best thing you can do for your grass is simply leave it alone.