Step 1: Scratch Out Thatch
Use a spring-tined rake to vigorously scratch out or “scarify” thatch. Treat moss and make sure it is dead before scarifying; raking live moss spreads the problem around.
Step 2: Aerate
Aerate the lawn every 2–3 years. This is easiest when the soil is moist. Drive in a fork, or on heavy soils use a hollow-tiner to remove cores of soil, every 4 in (10 cm).
Step 3: Apply Dressing
Apply top-dressing directly after aerating, spreading the mixture evenly over the surface—one bucketful will cover approximately 6 sq yd (5 sq m). Make top-dressing using 3 parts sandy loam, 6 parts horticultural sand, and 1 part peat substitute (such as composted bark or coir).
Step 4: Work it In
Work the top-dressing well into the grass and the air holes using the back of a rake or a stiff broom. To make the job easier, allow the mixture to dry slightly before brushing it in.
Step 5: Spread at Right Angles
Apply a fall lawn fertilizer at the rate recommended on the package. For an even spread, scatter half the fertilizer in one direction and the other half at right angles to it.
Step 6: Seed Sparse Areas
If the lawn looks sparse, sprinkle it with some seed. Choose a seed type to match the rest of the lawn and use about half the amount recommended for sowing a new lawn.
If not repaired, damaged edges will continue to deteriorate, and like any bare patch, they also provide an open invitation for weeds to establish. Reseeding a damaged edge is rarely effective, so try tackling the problem using this simple technique.