Thatch

Gardeners know about plants becoming pot bound and needing to be re-potted now and then. Lawn grasses can be said to become pot bound as well.

As lawns grow and spread they produce a layer of thatch just above the soil. Thatch consists of intermingled living, dead and decomposing plant parts. It is a natural part of the living turf and generally desirable, if less than 6mm thick.

Contrary to popular belief, it is not formed from the grass leaves that fall into the lawn turf after mowing but a mixture of living and dead grass stems, crowns and roots.

Thatch forms for several reasons, but the most important is improper fertilisation. When grass is growing properly, it forms new roots, stems, and leaves as the old ones die.

As long as new grass is formed at about the same rate as the old dies, there will be no thatch accumulation, but when the grass grows faster than the old material can be destroyed, thatch accumulates.

If the thatch becomes overdeveloped, the soil beneath can become compacted, making it difficult for roots to grow, and limiting the movement of air, moisture and nutrients through the soil. This layer of matter can also form an ideal environment for disease and insects.

If your turf is spongy and soft when you walk on it, and you can see a thick layer of brown, spongy material when you look into the turf, you may have a problem with thatch.

To control and cure the problem:

Make sure you fertilise your lawn properly. Too much fertiliser will encourage thatch accumulation.

Also, proper watering will encourage the roots to grow deeply and prevent your soil from becoming compacted.

Occasional raking and brushing should prevent its build-up, but scarification is essential for the removal of excessive thatch and early autumn is the best time for this treatment when the production of side shoots will be stimulated, resulting in a denser, healthier lawn the following spring. The extra protection afforded by an annual top dressing may be necessary.

If your lawn suffers with excess thatch then we will suggest that it is thinned by scarification.

Click here to learn more about scarification.