University of Illinois Extension

Composting for the Lawn

There certainly has been a strong movement in gardening to return all that can be back into the soil, keeping perfectly good organic matter out of the waste stream, said Richard Hentschel, a U of I Extension horticulture educator.

"Applying compost is easy enough in our vegetable garden and flower beds where there is a lot of open space each spring that allows the gardener to turn the compost into the garden beds. However, what can be done with the lawn that deserves that organic matter too," said Hentschel. "Organic matter coming out of compost bins and piles can be used to top dress our lawns just like we use black dirt."

In our beds, gardeners do not worry about those occasional bigger pieces that have not completely decomposed. Gardeners will either return them to compost further or go ahead and turn them into the bed to finish being broken down right in place.

Composting

For use in the lawn, screening the compost using a homemade sieve will make your top dressing job a lot easier.

"It is easy enough to fashion your own screen using one by four or two by four lumber, creating a frame that sits over the edges of your garden cart or wheelbarrow," he said. "Use hardware cloth that has one-half inch openings and cut to size and secure to the wooden frame using nails or staples. This screen can be very basic or a work of garden art, depending on your skills."

The better composted material will likely be near the bottom and into the center of the compost bin or pile. This is the area that has seen consistent temperatures and moisture throughout the composting cycle and will be more completely broken down.

"Nearly all of that material should easily pass through the screen or will not need to be screened at all," said Hentschel. "The farther you get to the top and outside edges of the compost bin or pile, the more screening will be needed. Those areas of the compost pile will have seen lots of variation in temperatures and can have easily dried out, slowing or even stopping the composting process. All of the organic matter that does not pass through the screen should be saved and used at the next composting cycle."

Once the organic matter has been screened it is ready to be spread on the lawn. With the exception of thin grass where you have exposed soil, your topdressing should go unnoticed by the neighbors.

"It is better to apply two or three lighter topdressings a season that one heavy one," he said. "You want to encourage new crown and root development and the active breakdown of the thatch layer to allow roots to develop and grow into the soil and not the thatch layer. There will be big benefits later on as the weather turns warm and your grass stays green longer and uses less water. Organic matter holds more soil moisture while improving drainage."

After you are done topdressing, overseeding is still possible. Lightly rake the seed into the newly spread compost. Keep in mind that overseeding needs to be done for your area when the soil temperatures promote quick grass seed germination. Depending on all the things that you contributed to your compost pile, gardeners will see the occasional plant out of place in the lawn or flower beds. It is pretty common to find a tomato plant or coneflower that has germinated from seed.

"Organic matter will continue to break down in the lawn, releasing the nutrients the grass plants need to grow," he said. "A healthier lawn is better able to recover from dormancy, a hot summer drought, a seasonal disease outbreak or the badminton match from the family reunion. If a gardener sticks with topdressing the lawn, using a well decomposed compost at least once a year, good things will happen."