The Truth About Moss

Moss is a familiar enemy to most lawn care technicians in the UK. The unfortunate truth is that our climate is perfect for it. Dark, wet winters allow moss to flourish; dominating any turfgrass species that are attempting to make it through the season. This guide will help you understand the many reasons why moss might keep returning to your lawns and will help you tackle the problem in the long term.

What is moss?

Mosses are ancient plants that evolved 200 million years before the appearance of flowering plants such as grass. Mosses are not like the other plants that we grow in the garden; they do not have roots; preferring to take all their water and nutrients directly through the leaf. They also have the unusual ability that allows them to rehydrate after drying out, a useful trait to have if you want to survive the summer!

Why does moss grow so well in some lawns?

Moss grows very well in damp, shady conditions so most British lawns will struggle to avoid moss growth in the winter months. Moss does not actually harm the grass plants but it will outcompete the grass if conditions are right. It is often said that presence of moss is an indicator of poor lawn health, this is true because if the grass is not healthy then it will not be able to compete with the moss.

Reasons for poor lawn health (and good moss growth) can be one or more of the following…

  • Waterlogged or very wet soil
  • Compacted soil
  • Shaded areas
  • Lack of adequate nutrients
  • Leaves not swept away
  • Increased stress levels (e.g. fertiliser scorch, herbicide applications, severe mowing)

It is no surprise then that if you don’t try to make the lawn less habitable for moss it will return each year.

What treatments are available for moss?

Fertiliser treatments

Iron sulphate has been used for many years as an economic and effective treatment against moss growth. It also has the added benefit of greening up the lawn making it highly popular as a winter treatment. Iron sulphate can be applied in granular or liquid form, there are benefits to both methods but a liquid application will give the fastest results due to the direct action on the leaf. Granular fertilisers such as Black and Green or First and Last +8%Fe allow higher levels of iron to be applied and a longer lasting blackening/green-up effect to be seen.

Other granular moss-treatment products have recently become popular that do not contain iron sulphate. These products often have high potassium content and require application at rates of 1,000 kgs per hectare (100g per square metre) or more. Beneficial bacteria and fungi are also added to speed up the natural decomposition of dead moss, reducing the need for scarification. The success of these products is varied and trials carried out by our customers in the autumn were not conclusive. Further trials will be carried out in the spring, if you are interested in joining the trial please contact us.

Physical treatments

Scarification is an excellent way to remove moss from lawns as well as thatch. It also plays an important role in maintaining lawn health year after year. The physical removal of moss will not prevent it from growing back but does allow the grass a chance to take hold. Scarification must be done in the spring or early autumn to allow the lawn sufficient time to recover otherwise the moss will just grow back.

Preventative measures

“Prevention is better than cure”, isn’t that what they always say? If a lawn struggles with moss every winter then addressing the underlying cause is the only way to prevent further problems.

  1. Increase lawn vigor. Apply adequate fertiliser to the lawn throughout the year to enable strong, disease-resistant growth.
  2. Scarify. Remove thatch buildup from the lawn to reduce the chance of fungal diseases and allow better access of air to the soil and roots. A high nitrogen fertiliser such as Ultimate 22-5-10 +2.5%MgO will encourage the lawn to thicken rapidly after scarification.
  3. Aerate. This has numerous other benefits for lawn health but it will also relieve soil compaction and facilitate better drainage creating a dryer soil surface.
  4. Mow correctly. Mowing at a very low height or cutting too much in one go will affect lawn health. It is also important to make sure mowing blades are sharpened regularly.
  5. General garden maintenance. Fallen leaves, large trampolines and over-hanging trees all affect lawn health. Encourage your customers to sweep leaves regularly, move trampoline and other garden furniture once a week and cut back or prune any overhanging trees or shrubs.

At GreenBest we’ve been doing business with lawn care professionals for almost 20 years, there isn’t much we haven’t heard! If you would like to discuss any of the topics covered above please get in touch by calling us on 01963 364788.

Daisy Lacey BSc(Hons)
Sales and Product Development
GreenBest Ltd

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