If you’ve ever tried to rake through a neglected lawn, you’ll know that it’s an almost impossible task – the lawn having seemingly become one big matted mess. The cause of this tangled web of woe is thatch, or too much thatch, to be precise.
Thatch is a tightly wound organic layer of dead and living stems, leaves and roots, which builds up between the layer of actively growing grass and the soil underneath it. It occurs because some parts of dead grass are slow to decay and rot (thanks to a compound called ligin), so when new stronger plants grow in place of the dead grass, a build up occurs.
It’s quite easy to identify a thatch problem. Viewed from the side, thatch looks like a thick brown/green layer wedged between the grass and soil. Of course, if you don’t fancy taking a chunk out of your lawn to do the side-on test, try walking on it barefoot – if is feels very spongy then the lawn could have a thatch problem. Finding that you can’t easily pull a rake through the grass without it getting stuck or lifting away the grass layer from the soil (a bit like rolling a carpet up) is also an indication of a serious thatch issue.
The effect that thatch will have on a lawn depends on how thick it is. Usually, anything more than ½ an inch is bad news. One of the biggest problems caused by thick thatch is extensive root accumulation, which can be vulnerable to desiccation in warm weather (this is because thatch heats up and dries out quickly), or lack of oxygen in wet weather (thatch holds excess water well). Mower scalping is another major problem, along with an increase in pests, including organisms and insects that can cause disease.
Thatch isn’t all bad though – in fact, anything up to ½ inch thick can be beneficial for lawns as it can insulate against extreme temperatures as well as variations in soil moisture. It’s also great at giving sports turf a bit of extra protection and resiliency.
So what can you do about thatch? Controlling thatch is actually quite easy. Each year in late spring and early autumn cut your grass a little shorter than usual, and then start raking! You’ll need to give your lawn a deep rake, though, so if you’ve got a large garden you may want to get a landscaper in to do it. An aerator will also really help in the control of thatch, and can be done at the same time.