Should You Let Your Lawn Go Dormant in Summer?

Cool-season lawns brown in midsummer heat unless water holds the color. The lawn water requirement calculator returns that cost for your grass and climate, roughly 1 inch (25 mm) a week for most cool-season lawns.¹ This article covers the other side of the trade: what a dormant lawn needs, what it risks and how much water you keep.

Below you will find water use by grass type, the survival amounts extension services recommend, a season's savings in gallons, and the lawns that should keep their water.

Is it OK to let your lawn go dormant in summer?

For a healthy, established cool-season lawn, yes. Dormancy is the grass's own drought defense: the leaves stop growing and turn brown while the crowns and roots below stay alive.² Kentucky bluegrass, fescue and perennial ryegrass all brown this way in midsummer when heat or a lack of water hits them.³

Virginia Cooperative Extension says summer dormancy in the mid-Atlantic usually follows 2 or more weeks of high heat, low humidity and little rain.⁴ If the lawn entered that stretch in good shape on good soil, its suggested strategy is to stop irrigating and let the grass go dormant, then expect a quick rebound in green color once significant rain arrives.⁴

Time is the limit. Turfgrass can generally stay dormant for 4 to 6 weeks without significant damage, and lawns are at risk beyond that.² Nebraska Extension puts typical survival at 4 to 5 weeks, falling to 3 to 4 weeks when temperatures stay above 80°F (27°C).⁵

Species matter too. Tall fescue roots can reach 3 feet (0.9 m) or more if the soil allows,⁵ and Illinois Extension notes the species often stays green longer in summer, though it can push its limits and die instead of going dormant.⁶ Warm-season grasses such as Bermuda, zoysia and buffalograss are a different case. They are adapted to hot, dry summers and almost always survive, with slower growth and some color loss under extreme drought.⁴

How much water does green turf need compared with dormant turf?

Missouri Botanical Garden publishes the most direct comparison, in inches of water per week by grass.³ Green means the lawn stays green and growing; dormant means it may brown but will not die.

Weekly water to keep lawns green and to keep them alive, by grass type

Inch values are from Missouri Botanical Garden's Table 1.³ Millimeter conversions and the share column are calculated here, rounded to the nearest whole number.

The sources do not agree on one dormant number. Missouri's run 40 to 67 percent of its green figures, while the Nebraska, Purdue and Illinois guidance in the next section works out to far less. Heat, soil and the length of the dry spell decide where you land, so use the higher figures if the lawn is thinning or the dry spell passes 4 weeks.¹

The green figure is not fixed either. Nebraska Extension estimates full water use for home lawns in July at 1.5 to 2 inches (38 to 51 mm) a week in the east of the state and 2 to 2.25 inches (51 to 57 mm) in the west, against 0.75 to 1 inch (19 to 25 mm) in April and May in the east.⁵ Dormancy saves the most in the hottest weeks, when the green lawn is thirstiest.

Your own green-lawn number depends on grass and climate. The grass type water needs calculator compares species, the lawn watering by grass type chart lists them in one place, and the lawn water deficit calculator shows how far rain and irrigation fall short of what your lawn uses.

How much water keeps a dormant lawn alive?

Extension services give survival watering as a small depth at long intervals instead of a weekly rate. The aim is to keep the crowns hydrated without greening the lawn.¹

Survival watering for dormant cool-season lawns, by extension source

Weekly equivalents are calculated here as depth divided by interval. Illinois pairs the smaller depth with the shorter interval, so both ends work out to the same rate. Illinois defines extreme drought as more than 4 weeks of hot weather with no rain.

Those schedules work out to 6 to 25 percent of the 1 inch a week that keeps turf green. Purdue's 0.5 inch every 2 weeks sits at the top of that range, at 0.25 inch a week.¹ Nebraska's 0.25 inch every 3 to 4 weeks for Kentucky bluegrass sits at the bottom.⁵

Soil decides how deep a given amount goes. Nebraska's soil table shows 1 inch of water wetting about 16 inches of sandy soil, 8 inches of loam and 5 to 6 inches of clay, so a 1 to 1.5 inch rescue soaking reaches roughly 8 to 12 inches (20 to 30 cm) in loam.⁵ The same table gives infiltration rates of 0.25 to 0.50 inch an hour for loam and only 0.10 to 0.25 inch an hour for clay, so a large soaking on clay runs off unless you split it.⁵

The soil infiltration rate calculator estimates your own rate, and the cycle and soak calculator splits a soaking into cycles. If puddles form, Nebraska Extension advises stopping for one to two hours and then resuming.⁵

How much water does dormancy save in a season?

The savings are the difference in depth multiplied by the area. Use depths that land on the grass, as measured in catch cans, so sprinkler coverage is already built in.

Take a 6,000 sq ft Kentucky bluegrass lawn through an 8-week dry stretch. The green option uses Missouri Botanical Garden's 1.2 inches a week for bluegrass,³ and the dormant option uses Purdue's 0.5 inch every 2 weeks.¹

1. Lawn area6,000 sq ft
2. Green-lawn depth1.2 in/week × 8 weeks = 9.6 in
3. Dormant-lawn depth4 waterings × 0.5 in = 2.0 in
4. Green-lawn water6,000 × 9.6 × 0.623 = 35,885 gal
5. Dormant-lawn water6,000 × 2.0 × 0.623 = 7,476 gal
6. Water saved35,885 − 7,476 = 28,409 gal
7. Share saved28,409 ÷ 35,885 = 79%

About 28,400 gallons saved, 79% less water

Metric: 6,000 sq ft is 557 m². The depths are 244 mm green and 51 mm dormant, so the lawn takes about 136,000 liters green, about 28,000 liters dormant, and saves about 108,000 liters.

To turn gallons into dollars, divide gallons saved by 1,000 and multiply by your price per 1,000 gallons. The lawn watering cost calculator does that with your own rate, and the inches of water to gallons calculator converts any depth and area.

When should you keep watering instead of going dormant?

Dormancy suits some lawns and gambles with others. The costs are a brown lawn, harder ground and more room for weeds. Illinois Extension lists appearance and weed invasion as the main downsides,⁶ and Purdue adds that dormant turf is more easily injured and may thin or die if a dry spell reaches 4 to 6 weeks with no rain or irrigation.¹

If you choose to water, deep and infrequent beats light and daily. Iowa State recommends 1 to 1.5 inches a week in a single application, or two applications 3 or 4 days apart.² The lawn watering schedule calculator turns that into days and minutes. If neither a brown lawn nor a water bill is acceptable, the turf removal savings calculator estimates what replacing part of the lawn would save.

How to care for a lawn in summer dormancy

1. Commit before the heat arrives. Breaking dormancy draws down the plant's stored reserves, and in continued heat it may not rebuild them,⁶ so choose one path for the whole summer instead of switching.
2. Mow high, and less often. Keep cool-season grass at 3 inches (76 mm) or taller. Illinois Extension suggests 3 to 4 inches (76 to 102 mm) and never cutting more than one third of the blade at a time.⁶ Taller turf shades the soil and holds in the moisture that is there.⁶
3. Skip nitrogen and weed treatments. Illinois Extension says to fertilize in early September, not summer,⁶ and Missouri Botanical Garden says midsummer weed killers can further damage the turf and work better in fall.³
4. Stay off the grass. Mowers and heavy equipment can cause substantial damage to stressed turf, which will not recover until rain returns.¹
5. Pick one survival schedule and measure it. Either give 0.25 to 0.5 inch (6 to 13 mm) every 2 to 3 weeks, or leave the lawn alone for 4 to 6 weeks and then apply 1 to 1.5 inches (25 to 38 mm) once and again 7 days later.² Do not stack the two. Place 2 or 3 rain gauges in the spray pattern to measure what lands.² The catch-can test calculator turns those readings into your sprinkler's rate, and the how long to water lawn calculator converts a depth into minutes. Count soaking rain toward the schedule; the effective rainfall calculator estimates how much of a storm your lawn can use.
6. Water in the early morning. Iowa State puts the best window at 5 a.m. to 9 a.m., and evening watering can add to disease problems.²

Should you water a dormant lawn to turn it green again?

Usually not. Once cool-season turf has browned, Illinois Extension advises leaving it dormant instead of watering heavily to force green-up, because breaking dormancy drains reserves the plant may not replace in hot, dry weather.⁶ Missouri Botanical Garden adds that watering a lawn already dormant in midsummer generally will not turn it green until fall.³

The exception is the rescue soaking after 4 to 6 weeks, where survival is the goal. Iowa State says the grass should begin to green up after the second application.² Otherwise wait for rain or cooler weather, then fertilize at the right time. Nebraska Extension puts most nitrogen for cool-season grass in fall,⁵ and Illinois Extension names early September for most lawns.⁶

How can you tell dormant grass from dead grass?

Dormant and dead turf look the same until water or rain returns. Purdue's turfgrass specialist says you cannot tell whether a dormant lawn is dying unless you water it and watch the response.¹ After the rain or rescue soaking, Virginia Cooperative Extension suggests checking within a few days, often the next day. Brush aside the brown leaf tops and look at the base of the canopy for green tissue and for new leaves coming from the growing points.⁴

Expect new leaves within about 2 weeks of the rains returning.¹ Kentucky bluegrass spreads by rhizomes and fills in quickly,⁵ and Nebraska Extension says spreading grasses can reclaim areas up to 6 inches (15 cm) across, while larger bare areas need reseeding or sodding.⁵ Perennial ryegrass and other bunch-type grasses cannot spread into voids, so weeds fill the gaps.⁵ Virginia Cooperative Extension advises planning fall reestablishment if grass is lost.⁴

Frequently asked questions

Sources

1. Merzdorf, J. (2012). Home lawn during drought: To water ... or not? Purdue University Agricultural Communication, quoting turfgrass specialist Aaron Patton.
2. Jauron, R. Watering Home Lawns. Yard and Garden, Iowa State University Extension and Outreach. Last reviewed June 2022.
3. Missouri Botanical Garden. How do I care for my dormant cool-season lawn? Gardening Help FAQs. Table adapted from Missouri Environment and Garden, May 23, 2012.
4. Virginia Cooperative Extension. Lawn Recovery from Drought. Turf and Garden Tips. Virginia Tech.
5. Schild, J.A. and Dworak, S. (2013). Water Wise: Drought Effects on Turf in the Landscape. NebGuide G2191. University of Nebraska–Lincoln Extension.
6. Illinois Extension. Managing Lawns During Drought. University of Illinois Urbana-Champaign.

Written by Daniel Reeves, PE, CID. Figures in this article were calculated from the cited sources and checked against our lawn watering calculator. Read how we calculate and our editorial policy. Spotted an error? Tell us.