Moss – Causes and Control

What is Moss?


Moss is a small flowerless green plant with no roots, which grows in damp habitats and reproduces via spores released from stalked capsules.


There are around 1,000 species of moss and with the UK being a particularly wet and cool part of the world for many months of the year, the battle to keep it out of lawns is forever ongoing. It grows well in damp, cool conditions .The difference between mosses and other plants is that they do not require a root system for survival, though some produce a structure called rhizoides. It has a remarkably high drought tolerance and requires little nutrition making it easily able to out-compete lawn grass and eventually take over the whole lawn. Due to the cooler and wetter climate in the UK it thrives during the months between October and March.

What causes Moss?

Moss can soon become a problem in all kinds of lawns. There are various reasons for why this can be the case, here are some below.

  • Poor drainage
  • Acidic soils
  • Thick thatch layer
  • Poor nutrition input
  • Shade
  • Mowing height too low
  • Poor air circulation
  • Poor grass coverage
How so I control Moss and prevent it in the future? The best methods of prevention and control are simply to combat the causes of the problem listed above. Moss thrives in damp, dark spaces where it has the freedom to spread. So lets look at how we can reduce the chances of moss encroachment.
  • Regular Aeration to improve surface drainage and compaction. This will allow your lawn to cope with moisture better and dry out quicker during the autumn and winter months.
  • Moss loves growing in acidic soils. You can find out the pH level of your soils by carrying out a soil analysis test. To alter your soil pH and make them more alkaline, applications of lime will help.
  • Scarifying your lawn on a yearly basis will help keep the thatch layer under control. Thatch in a lawn acts like a sponge, holding onto moisture on the surface which moss will thrive on.
  • A poor nutritional programme for your lawn can lead to the grass struggling and becoming thin. Thin lawns are susceptible to moss as this allows the plant room to spread through moss. A good, healthy grass coverage = less moss.
  • Shaded areas caused by over hanging trees and shrubs create a perfect environment for moss, and a challenging one for grass. If possible, cut back the reason for the shade to create better growing conditions.
  • Mowing too short, and with a blunt mower blade will put the grass plant under stress allowing for moss to encroach. We advise mowing between 25-40mm in height during the growing season, and raising that up a fraction during autumn and winter.
  • A dark, damp habitat is best for moss. By improving air circulation by cutting back tress and shrubs and carrying out regular aeration will assist you in the battle against moss.
  • A lack of healthy grass coverage can lead to a moss (and weed) problem in your lawn. The best approach to containing moss development is to ensure your lawn is thick and healthy with a very good coverage of grass.
  • An alternate method of control is applying an iron based moss control/killer to dehydrate the moss to prevent it spreading, followed by scarification. Moss is an extremely difficult plant to kill completely, therefore applying an iron treatment to contain it, then removing the moss from your lawn via raking or scarifying is a very successful method. If your lawn has a moss problem, why not fill in our Contact Form to arrange your Free Lawn Survey to see how Will’s Norfolk Lawns can help.