How to scarify a lawn

Autumn is the best time of year to pull out thatch and dead organic matter from the surface of your lawn (a process called scarification). So, in this post, I am going to go through the basics of how to scarify a lawn.

Does my lawn need scarifying?

Many lawn owners don’t fully understand why they should be scarifying their lawn, they’ve just read that it is beneficial. Learning why lawn professionals scarify is very important to know and it is worthwhile learning how to spot if a lawn needs scarification or not.

Before you do anything, get down on your hands and knees and have a look really good look at your grass. Scrape down into the sward (the surface of the lawn) and try to find the surface of the soil. A healthy lawn will have strong, green grass plants and very little dead organic matter on the surface of the soil. If you have to dig down a little way to find the soil, then a light scarification will pull any dead matter out and let the lawn breathe. If the surface of the soil is several centimetres down, and the grass is generally spongy, then you’ve got a tough job ahead!

Scarifier or lawn rake?

One thing that does annoy me is that many garden advice sources use lawn scarification as a very broad term, describing any action where you are raking the lawn. This is incorrect, as there is a big difference between lawn raking and scarification.

Lawn raking is a very light process, involving either a manual hand rake or a cheap electric machine. These are largely ineffectual at actually removing a problem thatch layer, as they are not strong enough to penetrate the soil. If they are used too much, they end up just ripping the grass to pieces, without improving it in any way.

A professional scarification machine uses a powerful motor to drive rotating metal knives into the surface of the lawn. These can remove an enormous amount of material from a lawn, while leaving the grass plants relatively undamaged. Once you’ve seen the results of a professional scarifier, you’ll want to put the lawn rake back in the shed for good!

I am often asked about buying a scarifier. They are expensive. Professional scarification machines can be hired from your local equipment hire shop, or save yourself a weekend and get in touch with your local lawn care technician.

Moss?

The process of scarification is not to specifically to pull out moss, although it does that as a result. The main aim is to improve the growing conditions for grass, so that the moss is discouraged. If you have a moss problem, then it is advisable to put down a moss control treatment at least two weeks before you aim to scarify, as this will make it much easier to remove and also prevent you from spreading the moss spores all over the rest of the lawn!

How to scarify a lawn

Okay, so you’ve got your scarification machine, you’ve applied your moss control treatment if you need to, you’ve picked a nice dry day and so are ready to scarify your lawn. The first thing to do is to make sure the blades are running at the correct height. Set the machine as high as it will go, start it up and then on a flat spot in the lawn, gradually lower the blades until they are just making contact with the soil. Go over a test area  and make sure that you are pulling out debris, but not destroying the grass! Then cover the whole lawn, up and down in the same direction (e.g. north and south or east and west), not round and round.

Once you’ve completed a full pass of your lawn, rake and bag up the debris. You can put this in your council green bin for collection or take it to your local green waste amenity tip. If your lawn contains a large amount of thatch then there will be LOTS of waste, up to an entire bin bag per square meter.

Next, check your lawn to see how it has fared, and have another dig down to see how much thatch is left. Many well-maintained lawns only need one pass so if you think that the job is done, reward yourself with a cup of tea and a sit-down. However, very few lawns are well-maintained, so another pass may well be required, and another, and another, and another! My personal record is seven passes over the same lawn and I was still pulling out thatch (and grumbling a lot).

Several passes

An important tip to remember when scarifying is to always direct the next pass at a 45 degree angle to the last. This will pull the most material out of the lawn the quickest way. It is also much better to scarify too much rather than not enough, as you can always over-seed and repair, but it is more difficult to scarify again if thatch is still left in the lawn.

Once you are satisfied with your work, it is a good idea to run a rotary mower over it to pick up any fine debris you may have missed through raking and this will also give you a nice clean finish. That is how to scarify a lawn.

To over-seed or not?

Straight after scarifying is the perfect time to overseed your lawn with new grass seed, especially if your lawn now looks like a battlefield. The lawn is thin enabling the seed to come into contact with the ground giving better germination. This will help the lawn to recover more quickly and introducing new grass will freshen your lawn, improve disease resistance and even up any inconsistencies in colour. A top dressing would also be beneficial to plant the seed, and help to level the lawn.

Problems with scarifying?

As Ursula Buchan found out, finding out how to scarify a lawn can be an extremely surprising. The machines can be heavy and awkward and the sheer amount of material that you can remove from a thatch-laden lawn can be mind-boggling. Raking it all up is tough, you’ll get tired and probably earn a number of blisters.

Achieving a good scarification result does improve with experience. I’ve scarified hundreds of lawns and can quickly tell those which are going to be difficult, and in my experience the biggest mistake you can make when scarifying a lawn is that you don’t hit it hard enough. It is much better to go over it far more than necessary and then re-seed, then leave a layer of thatch which then suffocates the lawn, preventing its recovery.

If you would like a quotation for scarifying your lawn, or even just some advice about it, and you live in the Exeter area of the UK, then please don’t hesitate to get in touch and I will be happy to advise.

Kris Lord
The Lawn Man