If you've seen a cross-section of soil and grass roots, you would have seen the layer of organic debris known as thatch. Grass propagates by seed, but some types also produce side shoots. These help the grass spread and are either aboveground (stolons) or below (rhizomes). The finer texture lawns can have a large amount of these shoots giving it a lush appearance.
If new grass blades form at a similar rate as old ones, and die and decompose at the same rate, thatch won’t occur. If new grass grows faster than old grass decomposes then thatch will form. A thin layer of up to 1cm is perfectly fine for your lawn and will offer a degree of moisture retention. Too much will prevent air,sunlight, water, and nutrients getting to your lawn. Over fertilising is usually the leading cause.
Common signs of lawn thatch
- It has a soft and spongy feel like a carpet underfoot.
- Water is slow to penetrate and runs off it when watering.
- Brown or grey thick patches in the lawn.
- The grass is slower to grow and thinner.
- The height of your lawn edges are higher and denser.
What is lawn scarifying or dethatching?
Scarifying or dethatching are essentially the same thing and is the process of removing the thick layer of thatch from the base of the lawn,to improve overall lawn quality.
How to remove lawn thatch
There are two main methods of removing thatch. Before scarifying your lawn, set your mower to a low setting and give it a mow and remove all the clippings. Do not set the height so low that it cuts into the thatch and scalps the lawn though.
Removing with a rake
- Dethatching rakes are designed with short, curved tines that are designed to catch thethatch and pull it away from around the grass.
- They are perfect for small areas and light thatch but can be very labour intensive.
- Rake across the lawn and grab the thatch with the tines, taking care to not damage the grass. You are better to do multiple light passes rather than heavily gouging the lawn and ripping out the grass.
- Mow up the thatch and remove from the lawn.
- There are two main types of scarifying machines used for lawns, petrol and electric.With both types the method is the same.
- Set the height of the scarifier to cut into the thatch and work your way up and down the lawn, taking care to note any high points and hollows and adjusting the height of the machine accordingly.
- Be consistent with your lines up and down the lawn and your pace, not rushing over some parts and sitting over others.
- Take care not to go too deep with the tines and rip into the soil and tear out the grass.
- Rake up the thatch and remove. Lawns with thick layers of thatch may need multiple passes to rake the thatch out.
How often do you scarify a lawn?
Spring and Autumn are the best time to scarify your lawn when they are actively growing. The frequency depends on how quick new thatch forms.
The Benefits of Scarifying Lawns
- Improves airflow around your grass and into the root system.
- Improved absorption of water and less runoff.
- Improved delivery of nutrients to the root system.
- Increased sunlight to emerging grass for healthier and stronger growth.
- Greener and stronger blades of grass and a uniform look to your lawn.
- Water well after scarifying. Deeper and less often is better than shallow and often.
- Over-sow and re-seed any areas that are bare or need any thickening up. Use a starter fertiliser such as Everris New Grass and Renovation formula. It helps repair and nourish new and struggling lawns and is gentle enough to apply after scarifying.
- Excessive thatch often is caused by excessive fertilising, only fertilise at the correct rate and to the lawn's needs.