The cool, wet weather this spring has helped produce lush, green lawns across Iowa. This spring's weather has also provided ideal growing conditions for mosses and mushroom (toadstools).
Mosses are small, thread-like plants that form mats on the soil surface. They are adapted to a wide range of environmental conditions. Mosses can be found in moist and dry sites, sun or shade, and in acidic and alkaline soils.
The appearance of mosses in a lawn is usually a sign of poor growing conditions. Conditions that encourage moss growth include excessive shade, low fertility, poor drainage, compacted soil, or any combination of the above.
Mosses can be temporarily removed by hand raking. (Mosses don't have true roots and rake up easily.) However, the underlying conditions responsible for the moss development must be corrected to achieve permanent control.
In shady locations, prune low-hanging branches of trees and shrubs to allow more light into the area. Plant shade tolerant grasses in shady areas. Fine-leaved fescues, such as creeping red fescue, hard fescue, and chewings fescue, can tolerate considerable shade. If turfgrasses won't grow, shade tolerant groundcovers may be the answer.
Conduct a soil test to determine fertilizer requirements. Most lawns should be fertilized at least once or twice a year to maintain a healthy, vigorous lawn. Apply lime only when recommended by a soil test.
Areas that are constantly wet because of poor drainage may need to be regraded so that water will drain away properly. In some situations, tile drainage may be necessary to correct the problem.
Compacted soils can be improved by aerating the lawn with a core aerifier in spring or fall. Core aerification should improve water infiltration and promote drying of wet soils.
Mushrooms (toadstools) are the reproductive or fruiting structures of fungi. Their appearance is usually indicative of decaying tree stumps or roots in the soil.
While mushrooms in the lawn may be somewhat annoying, most cause no damage to the grass. There is nothing that can be applied to the ground that will prevent them from coming up. Simply mow them off or rake and discard them when they appear. Eventually, the mushrooms will stop emerging with the arrival of warmer, drier conditions. However, they may continue to appear periodically over the next several years during favorable environmental conditions. The mushrooms will disappear permanently when the organic matter in the soil has been exhausted.
This article originally appeared in the June 8, 2001 issue, p. 67.