Reviving your lawn after winter’s freeze and thaw

COLUMBUS, Ohio—If your lawn is more brown than green or dense with dandelions, you can probably blame Mother Nature.

Those shifts in temperature we appreciated in Ohio last winter, moving from freezing to above freezing and back and forth, have taken a toll on lawns across the state.

As the underground moisture froze and thawed repeatedly, the water in the soil expanded and contracted, and that could have pushed up roots, exposing them and possibly killing them, said Todd Hicks, turfgrass pathology program coordinator with The Ohio State University College of Food, Agricultural, and Environmental Sciences (CFAES).

“Some peoples’ lawns look like they were seeded with dandelions,” Hicks said.

Other lawns came out of winter with many bare patches of soil, having never recovered from the damage done last summer and fall. Diseases, especially gray leaf spot disease, were common in Ohio and across the Midwest last year, Hicks said.

Gray leaf spot is caused by a fungus, and last summer’s heat and frequent rainfall offered “the perfect condition for this fungus to grow,” said Joe Rimelspach, turfgrass pathology specialist with CFAES.

The disease can kill off perennial ryegrass, a grass common in lawns across the state.

If homeowners tried to reseed their lawns in the fall, which is typically a good time to renovate lawns, the weather didn’t cooperate. After the warm weather ended in early October, wet and cold conditions the rest of the season prevented successful seeding, Rimelspach said.

That’s because most lawns across the state are composed of cool-season grasses—bluegrass, ryegrass, fine fescue, and tall fescue—and they grow best in mild autumn and spring weather. Last year, when the weather changed from being too hot to grow those grasses to too cold, the cool-season grasses did not have enough time to fill in before winter.

“Don’t get discouraged,” Rimelspach said. “It will be a slow process. Chances are it’s going to take you a good part of 2019 to get your lawn back in shape, back to having the lawn you really want.”

Fall is a better time to reseed than summer, he said.

Some homeowners might not ever know exactly what led to their lawn looking so bare or brown. It could have been a disease, an insect, the weather, or some combination, Hicks said.

“I tell people it’s like when a relationship ends. You can dwell on what happened and why, but it’s over. Breakups happen. You don’t have grass. It’s time to forget about why and move on.”

Below are tips on replanting:

1. Use a slice seeder, if possible, to make sure the seed has good contact with the soil, so the seed has the best chance of germinating.

2. Purchase quality seed containing as little weed seed as possible. Be sure to read the seed bag label. The label will provide a percentage breakdown of what’s in the bag. 

3. Choose a good starter fertilizer. The numbers on the bag represent nitrogen, phosphorus, and potassium levels (N-P-K). A high-quality fertilizer might have 12-12-12 (meaning 12% N, 12% P, and 12% K) or 12-24-5 (12% N, 24% P, and 5% K). The phosphorus amount is particularly important because phosphorus is a key nutrient used for root growth and development.

4. Mow the lawn so that it’s no shorter than 2 ½ to 3 ½ inches. This enables the turf canopy to stay thick and dense, which reduces the amount of sunlight reaching the soil. Without adequate sunlight, weed seeds will not germinate.

5. If you water your lawn with a sprinkler, try using a pie pan or another container to collect water to ensure that the lawn gets enough water. Place the container near the sprinkler. When the water level in the container reaches about 1 inch, the grass is sufficiently watered. It is also helpful to periodically insert an instrument, such as a hand trowel or screwdriver, into the ground to ensure that the water is reaching the roots.