When we last left our lawns, back in fall, some weren't looking so good. Last summer's extended drought, coupled with higher than normal temperatures for longer than usual, stressed the grass. That was especially true in areas that never receive tree shade. Many homeowners elected not to water, knowing that grass usually does recover from lack of rain. A month without water is usually "not too much of an issue, depending on the time of year," says Lisa Johnson, horticulture educator at Dane County UW-Extension. "But last summer was very hot and for a longer period."
As the snow finally recedes this spring, homeowners will get a better idea of the state of their lawns. How to fix them? If you have large dead areas, now could be a good time to re-evaluate the idea of turf and look into native plantings or a rain garden. If you want to rebuild your turf, read on.
First, suggests Johnson, people should "evaluate what is in those spots - some turf? Crabgrass? Or other weeds?" If there is some turf coming up green, you may have some surviving grass, probably Kentucky bluegrass, and it may reestablish. However, it may also need your help.
Rake up the area and add soil, then reseed. Johnson says the usual time would be "starting about the middle to the end of April, but this year it's been a little colder." The situation to avoid is getting the grass seedlings going and then experiencing a good freeze. Johnson recommends waiting until the latter part of April this spring.
Read the grass seed bag
Many different mixes will work, says Johnson, but she also advises against buying a very inexpensive generic grass blend: "With grass seed, you tend to get what you pay for."
If the area tends to be dry, she recommends a blend that has more fescue than bluegrass; normal conditions would call for more bluegrass than fescue. Avoid blends with annual or perennial rye, though a blend with a small amount of perennial rye would be acceptable.
Coddle your creation
Covering the new area with straw is helpful as a mulch. (Make sure that the straw is free from weed seeds.) More expensive are biodegradable seed mats (these do not actually contain the seeds), which may be necessary to hold seed in place on slopes. Most important, however, is watering: Make sure the seeds do not dry out. Start watering right away. Johnson points consumers to the directions on the seed bag for correct watering procedure, but says it usually requires an inch of water a week. Once a day for 3-5 minutes is another rule of thumb.
Grass might begin sprouting quite soon or take up to a month, depending on the temperature, but continue to keep the area uniformly moist but not mushy. Keep watering after sprouts start to appear, because different seeds in the blend will germinate at different times.
Aerating compacted soil may help the root system of your grass. Compacted soil means grass develops a shallow root system, which makes it less resistant to drought. Johnson recommends aerating lawns every two years; however, she adds that aeration does not go very deep. Note that aeration should be done before reseeding.
What kind of grass?
UW-Extension turfgrass specialist Doug Soldat studied the effect of the drought on local lawns. He found that fine fescue did not do well in last summer's drought, even though it is often planted with a "strong reputation for being drought tolerant." He does not recommend reseeding with fescue except in very shady areas. Overall, fine fescue does better in lawns that are highly cared for by lawn professionals. Fescue will not fill in dead spots as does Kentucky bluegrass.
Soldat found that Kentucky bluegrass did better than expected in the drought conditions of 2012. Kentucky bluegrass is commonly used for lawns in Wisconsin, and, although it will turn brown in dry conditions, it has a more robust root system and will come back. Reseeding with Kentucky bluegrass is a good option. It germinates slowly (up to three weeks), however.
The main things to remember about spring restoration, says Soldat, is that this is when weeds are also intent on re-establishing themselves. He warns that using a pre-emergent herbicide to prevent crabgrass will also prevent grass seed from growing.
Perhaps more crucially, digging to prepare the seedbed also creates a welcome mat for weeds. Soldat recommends prepping the soil with a slit seeder: "It cuts slits in the soil about an inch apart, and digging up only a tiny area gives the grass a competitive advantage."
Lastly, Soldat notes that "the reason the grass died in that spot is that soil was not good enough for that grass. You want to improve the soil health; otherwise the next time there's a drought, the grass will die there again." He recommends core aerating and also spreading compost to build up the soil health over time, about 1/4 inch in the spring and again in the fall.
For Soldat's report, see here (PDF).