Either you have a drainage problem or poor nutrition.
With moss on your lawn you will need to remove as much of the moss as possible before you start to take action to prevent it from coming back again.
Aerating the lawn will help to solve the problem.
There are various ways that this can be done.
The best way to aerate your lawn is with a coring machine that actually pulls small plugs of approximately 2 inches from the lawn.
It is possible to hire these machines or get a professional to do the job for you.
Alternatively you can aerate your lawn by using a garden fork and punching holes throughout the affected area.
This can be quite time consuming and tiring.
Another way to improve your lawn is to rake the lawn vigorously, and in doing so you will be removing the moss and any old grass clippings and other debris that is lying around.
This procedure is called scarifying.
You can then use a lawn specific moss killer to kill off any moss that is left.
It is important that you get a moss specifically formulated for lawns as ordinary moss killers can also kill your lawn.
As the moss dies it will turn black and the lawn might look unsightly for a while but once the moss has died you can scarify it again to remove the dead matter.
Scarifying the lawn will allow the water and fertilizer to reach the roots of the grass and improve the quality of your lawn.
In areas of your property where there is little or no sunlight and quite a lot of dampness, you might need to consider if it would be better to transform it into a garden that will cope better with the conditions than lawn.
