Battling the lawn moss epidemic

By | 19/02/2013
A lawn with a lot of moss

This year, moss has reached almost epidemic levels on lawns all across the UK, with very few avoiding being swamped by the troublesome and invasive Bryophytes!

Last year I published a post about how the warm winter of 2011/2012 created fantastic conditions for moss. However, almost unbelievably,  this year has been much worse!

After the second wettest year since records began, I can’t remember a week that hasn’t contained at least one day of rain since April 2012 (that’s ten months!) and I have talked about its effects several times during the year.

Some of the lawns which I maintain are on a heavy-clay base and have suffered terribly from the unusually high water table this year. This causes lawns many difficulties, including the leaching of nutrients and subsequent deterioration of the health of the grass, lack of available oxygen in the soil suffocating the grass and increased compaction due to the air pockets in the wet soil being squeezed out.

Consequently, the humble grass plant has had a tough time, struggling in wet soil and not finding enough sunshine in the cloudy skies to recover. Where the grass finds it difficult to grow, moss will inevitably find a way in.

But why has my lawn become covered with moss?

The ingress of moss on a lawn is always a symptom of grass that is struggling in some way. The best way to combat it in the long-term is to try to address this problem. Unfortunately, the weather can be one of the reasons the grass weakens and there is not much that can be done about it, but hopefully poor weather conditions are usually only temporary.

However, some lawns do cope much better than others. Here are some things you can do to keep your grass healthy and keep the moss at bay.

Moss prevention tips:

  1. Reduce the amount of shade on the lawn. This can be as simple as cutting back any overhanging trees and shrubs and trimming the tops of hedges. However, sometimes nothing can be done about a shady lawn, for example if it is behind a wall.
  2. Improve the soil conditions. Wet soil causes lots of problems for grass and moss loves it. Conversely, if the ground is too dry and excessively compacted, moss will find its way in.
  3. Check and adjust the soil pH. The acidity level in the soil is key to the availability of nutrients. Grass thrives in a slightly acidic soil, a pH of around 6-6.5. Any lower than this and key nutrients will be locked in, weakening the grass.
  4. Maintain a low level of lawn thatch. Thatch in a lawn is the layer of organic material such as leaves and debris which slowly decomposes on the lawn surface. If this layer becomes too thick it will gradually drown the lawn. Scarification is advised at least every two years to keep the levels of thatch nice and low, allowing the soil to breathe.
  5. Keep your mower blades high. One of the most common causes of moss ingress can be easily fixed by simply raising the height of your mower blades. Long grass is healthy grass! For the UK cool season grasses, 2-3 inches (50-75cm) is generally the perfect height.
  6. Keep the soil aerated. The soil is home to billions of soil-borne bacteria. These decompose organic matter and transfer nutrients into a form the grass can access. These bacteria need air and water to thrive and if your soil becomes compacted, the number of these bacteria will reduce and the grass will suffer. Aerating your lawn annually is recommended.
  7. Keep the grass healthy through a balanced fertilisation regime. Fertilising your grass throughout the year is strongly recommended because a managed lawn naturally loses nitrogen due to the lack of organic matter being recycled. Keep it fed regularly, but don’t overdo it! Little and often is best.

Following these simple tips will hopefully prevent moss from becoming a serious problem.

How do I remove the moss from my lawn?

If moss has taken hold then you’ll need to physically remove it from the lawn. To do so, follow this simple routine:

  1. Put down a moss control treatment in late winter or early spring, as long as the weather permits. A still day in February, March or September are usually best.
  2. Two weeks later, either rake it out in patches, or lightly scarify the whole lawn. The amount needed will depend on the severity of the moss infestation, but if you are not planning on overseeding, just pulling out the moss should suffice.
  3. Feed the grass with a high-quality, slow release fertiliser. This will strengthen the grass, and promote leaf growth to smother any remaining moss plants.
  4. Enjoy your moss-free lawn over the summer!

If you have any questions please don’t hesitate to get in touch.

Kris Lord
The Lawn Man

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