Answer: Moss grows on lawns because of too much shade, high soil acidity or poor soil fertility, explains Peter Landschoot, turf grass specialist at Pennsylvania State University in University Park. By removing the trees shading the lawn, you've eliminated one of these causes, says Landschoot. Moss may invade areas that get less than three hours of direct sun per day. Next, take a soil test to determine if the pH is between the optimum 6.0 to 7.0 and if the soil has the right nutrients. If the soil test says nutrients are needed, top-dress the area with compost so the soil base is at least four inches deep and add enough lime to adjust the pH, recommends Landschoot. Once the soil nutrients and pH are corrected, follow these procedures: In spring, rake the mossy area with an iron rake to pull out as much of the moss as possible and loosen the soil. If the area gets full sun, reseed with a mix of Kentucky bluegrass; for partial shade, seed with a mix of fine fescue. Lightly rake the area, covering the seed with 1/4 inch of soil and keep the area moist, advises Landschoot.
Q&A Library Searching Tips