We suggest the scarifying process to remove moss, thatch and other dead matter is undertaken at least once a month throughout the mowing season. Scarifying is an essential process that needs to be done to help you achieve the perfect striped lawn you've always dreamt of. Is your lawn spongy to stand on? Do you suffer in the dry summer keeping it looking green? You may well have a thatch issue! Excessive thatch levels can stop vital water, nutrients, oxygen and fertilisers reaching the grass roots starving your lawn of everything it needs to be healthy. Thatch is essentially a build up of dead material, grass clippings and leaves etc that forms a layer underneath the surface. 
You can check the thatch levels in your lawn by digging out a small sample of your lawn. You will be able to see the soil level compared to the thatch level as well as how developed your roots are. Around 5-6mm of thatch is healthy- anything above this and you need to start a thatch reduction programme. A thin layer of thatch will prevent evaporation if it is dry. A deep thatch layer will absorb fertiliser and water and prevent it getting down into the root zone which results in money wasted.
How can we get rid of thatch?
We recommend scarifying little and often! You can use a handheld rake to remove thatch and introduce air into the thatch so its more likely to break down. This is the simplest most cost effective way however as you can imagine this is going to be hard work and you're going to be left with piles of thatch to clear up after. At Allett we have come up with other solutions to make life easier for our end users and to achieve results more quickly. We have designed a number of easily interchangeable cartridges to help you get rid of thatch WITHOUT using harmful chemicals. Please check our product specifications online to see if your machine will allow you to insert the cartridges.
We have designed a Verticut cartridge in order to vertically cut down into the thatch level. This cartridge effectively lifts lateral growth (flat lying grasses) and removes moss which helps encourage tillering and new growth. The blades of the Verticut cartridge reach down into the thatch without damaging the healthy grass, which brings the dead layer to the surface to be collected and removed. Air is introduced into the sward to help break down the organic matter. Some broadleaf and grass weeds are discouraged by the closing cutting action of this cartridge. All debris is collected in the machines grass box reducing clear-up time. We would suggest verticutting at the same level you cut at and then dropping down to S if you're not achieving anything. Verticutting regularly at least once a month will help thicken up your lawn.
Another option is the Scarifier cartridge. This cartridge is gentle and can be used throughout the mowing season to keep on top of your thatch levels- we suggest once a month maybe twice. The Scarifier cartridge is Allett’s most popular cultivation cartridge and is designed to remove thatch, surface debris and dead moss. This cartridge also helps lift lateral growth upright before mowing. The rotating spring tines are relatively gentle on the lawn and this cartridge can be used most of the year without fear of damage to keep on top of thatch levels aswell as being useful to collect up leaves during the autumn. The use of the spring tine allows for safe cultivation where tree roots may be close to the surface. This is the best cartridge for beginners to turf cultivation as it is unlikely to cause damage if set too deeply but will give great results if used regularly. You should be looking to scarify on the 'S' setting on your Allett machine however you can raise this if you feel it is too aggressive and then lower it as you get to a more manageable level. You can pick up leaves using the scarifier cartridge at a higher setting - say 4 or 5. Your lawn should be moss free and firm to walk on once free of thatch- get down on your hands and knees and check between the grass blades for any moss. You should scarify in the pattern of a union jack. 
The next cartridge is the Dethatcher cartridge. It's much more aggressive than the verticut cartridge and is often used on lawns that are in serious disarray. The Dethatcher removes the densest layers of thatch effectively. The machine works by rigorously penetrating the soil’s surface in order to pick up and remove layers of thatch such as dead grass and leaves, plant stolons and weed growth. Lawns grow healthier, thicker and more luscious once this has been removed as it its less susceptible to disease. Lawns that are more susceptible to disease encourage moss growth which should be avoided. You should dethatch on the S setting however you can raise this if it is too aggressive to setting 2 or 3. You may need to re-seed some areas when using this cartridge.
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You can find a video on 'How to Scarify Your Lawn' here!