During the course of a season dead grass (called thatch) and lateral grass stems build up, thus restricting light and air getting through to the grass roots.
As thatch builds it restricts any desired grass and instead moss and weeds are encouraged to take over, leading to a downward spiral in the health of a lawn.
A scarifier is in effect a vertical mower with knife blades (or wire tines) spaced out along a reel - much like a cylinder on a mower.
These vertical blades act like a vigorous comb, forcing out any build up of rubbish at grass root level.
Early autumn is the best time for a deep penetrating scarification and thorough clear out of moss and thatch. The soil is also at the best optimal temperature for grass seed germination.
Seeding in autumn also allows enough time for new seed to germinate and for the grass to establish itself well enough for one or two light cuts, with a rotary mower, before it passes into a semi-dormant state for over-wintering.
If you are carrying out any scarifying in the spring it is best to wait until the frosts have passed and the soil has warmed sufficiently so that the grass roots may recover sufficiently
Some points to keep in mind
- Its best to kill the moss first
- its advised to feed the lawn after scarifing