Spring scarifying (verticutting)

Spring or autumn?

Autumn is the best time for heavy scarifying, because the grass recovers in cool, moist weather with few weeds competing. Spring scarifying is useful when thatch or moss is bad enough that the lawn cannot wait, or when autumn was missed. Keep it lighter than in autumn: the grass has to recover before summer heat arrives.

When

In April, once the grass is growing strongly and you have mown it two or three times. The soil should be moist but not wet. Avoid early spring, when the grass is still slow and will not fill the gaps.

How

1. Treat heavy moss with iron sulfate a week or two before.
2. Mow a little shorter than usual.
3. Set the blades so they just reach the thatch layer, not deep into the soil, and make two passes at right angles.
4. Rake out and remove all the debris.

Afterwards

Overseed thin areas straight away (see spring overseeding), feed, and water in dry spells. The lawn looks rough for two to three weeks and then thicker than before. For the heavier autumn job, see autumn scarifying.