In the spring, remove excess thatch with a heavy rake or de-thatching equipment. This helps to open your lawn to water, air and nutrients.
For severe thatch problems, aerate your lawn and lightly topdress with about a 0.5 cm (1/4 inch) layer of soil made up of equal parts loam, sand and organic matter.
What is thatch?
Thatch is that accumulation of organic debris such as dead leaves, grass stems and roots found between the soil and the living green parts of your grass.
In healthy lawns, insects, earthworms, beneficial fungi and other micro-organisms break down thatch and aerate the soil.
Excessive watering, overfertilizing with nitrogen, and heavy pesticide use decreases the populations of soil organisms required to keep thatch levels down.
Thatch that is more than 1 cm (1/2 inch) can prevent water, air and nutrients from getting to the roots.
Source: Lawn Maintenance brochure, Health Canada, 2002.