All established lawns build up thatch over time.
Thatch is not an unnatural occurrence. Rather it is natural consequence of the grass life cycle. As grass ages and dies, it begins to compost and become absorbed by the soil. The composted grass provides nutrient for the soil, in turn encouraging new growth.
In a healthy lawn, the typical level of thatch should not present a problem. Indeed, it provides a natural cushion as well as additional nutrients as it decomposes.
Before dealing with the excess thatch best practice is to aerate the lawn. The best times for undertaking this task are mid to late spring, or early fall both of which allows the lawn to recover during the best growing seasons.
Most lawns will benefit from periodic aeration. However, a heavily thatched lawn may particularly suffer from compacted soil, which reduces growth.
You should aerate at least once a year, perhaps even twice if the soil contains a high level of clay.
Aeration is the process of creating holes in the lawn allowing the soil to loosen. The holes are regularly spaced and can be created either by spikes or by removing plugs.
We have created a detailed guide on aerating lawns for your benefit.
Dealing with Excess Thatch
Once your lawn has been aerated, it is sensible to dethatch your lawn.
Occasionally, thatch does build up to excessive levels and your lawn will need some help in removing it. Too much thatch can stifle new growth and cause bare patches to appear.
We provide a detailed guide on the best way to dethatch your lawn.
Lawn Grass and Thatch
Thatching can expose areas of your lawn where there is no longer grass. This is a sign of problems. When a lawn is healthy, the grass develops side shoots, which fill grassy voids. This is particularly a problem with ryegrass lawns.
Bentgrass lawns suffer most from thatch and the process of aeration and dethatching should bring the lawn back to new in only a few week.
Fescue lawns often appear as though they are suffering from thatch, but if you dethatch such lawns in the same way as bentgrass lawns you can create a great deal of damage from which the lawn may not recover. Older, mature lawns were often a blend of fescue and bentgrass and although mature may well suffer from such thatch problems.
After Aeration and Dethatching
Overseeding after aeration can return your lawn to a healthy state. Image source Nuleaflawncare.com
A newly aerated and dethatched lawn can look in a poor state. However, do not worry. By following these steps, the lawn will quickly return to full vibrancy.
- Break up and spread the plugs from the aeration process on the lawn. They will quickly be reabsorbed into the soil.
- Soak the lawn well to provide a nurturing environment for new seed.
- Add a thin layer of phosphorus based fertilizer.
- Scatter new seed over the newly prepared lawn. This should help the grass recover any thinning or bare patches discussed above.
- Add a thin layer of mulch to protect the seed and provide them with additional nutrients during their germination phase.
- Water the whole lawn again.
- Leave the lawn for two to three weeks before walking on it again to allow the germinating seed to take hold and for the lawn to recover fully from the dethatching process.
- Keep the lawn regularly watered during the initial growing phase to encourage both the absorption of the plugs and the healthy germination of the new seeds.
Remember, a newly seeded lawn needs care and patience. Rushing the process can render the new grass weak and not uniform.
Other Causes of a Patchy Lawn
It is worth noting that a patchy lawn may well not be down to excess thatch. Other causes of problems include too much shade, too much moisture or simply down to a high level of foot traffic, which simply wears the lawn down faster than it, is able to recover.
Unfortunately, aeration and dethatching may not solve these problems, the solution for which will depend upon the particular diagnosis of the problem.