Moss can be a very common problem in a lawn, especially after very damp winters where near constant rain has created the perfect environment for moss to thrive. This resilient little plant grows and spreads quickly and in the right conditions it can spread across the whole lawn, forming a thick, spongy mat, which as well as being unsightly can make the job of mowing incredibly difficult.
What causes moss?
Moss can easily spread into your lawn through spores in the air. Once these settle in your lawn and start to grow they can spread from one area to another through shoots from an existing plant to spores sent out over wide areas. When these find dark and damp areas they can take hold and thrive. A few causes of a mossy lawn are:
Excess thatch: Old plant stems and organic matter naturally accumulate in a lawn. This organic matter does not break down easily but it does hold water in the surface of the lawn. These are ideal conditions for moss to grow.
Weak grass: A lawn is a competition of different species. If the grass is weak and thin then moss and weeds can easily spread in and fill the gaps where grass would otherwise be. Lack of fertiliser, irregular lawn maintenance or drought stress are common causes of a weak lawn.
Shade: Especially under trees is the perfect place for moss. Lack of sunlight and nutrients make the grass thin and weak but the damp shade is ideal for moss to grow.
Mowing too short: This is never a good idea as it can cause the grass to become weak and thin, especially in the winter. If the grass is weak moss will overpower it and move in.
Compacted soil: High traffic areas or well worn lawns will suffer with moss, where the soil is compacted nutrients will struggle to reach the roots resulting in a weak grass plant and the invasion of moss.
So how do you get rid of moss on your lawn?
Step 1: Moss Killer
A good moss killer solution should be your first call. There are many different types of lawn moss killer and you should follow the label directions of your chosen solution, they commonly have the same effect of dehydrating the moss, turning it brown or black and effectively shrinking it away from the grass and allowing the grass underneath to breath, grow and spread out.
If your lawn has low moss levels then this single step may be a sufficient treatment on its own. Well done no more moss.
However, if you have a considerable amount of moss in the lawn, the moss killer may not penetrate fully into the moss and the results will be poor, with moss likely to quickly return. We recommend moving to step 2.
Step 2: Scarification
This is what we call the process of physically removing the thatch and moss from the lawn, essentially scraping it out and opening up the lawn to allow air and nutrients to reach the grass plant. You can use a variety of tools for the job:
Spring tine rake: This is ideal for small lawns where a heavy machine may be cumbersome
Electric scarifier/lawn rake: A good compromise for a small to medium lawn fitted with flexible spring tines. Faster than by hand but may need a couple of passes to achieve the best result.
Petrol scarifier: This heavy duty machine is often fitted with solid blades. Ideal for larger lawns but also more efficient. One pass is usually sufficient to remove enough moss and thatch. Can be expensive so renting may be a better option.
The aim of this process is to remove the moss and thatch from the lawn. This will allow the lawn to breath and allow air, water and nutrients to reach the rootzone, and giving the grass space to spread into.
Scarification step 1: Remove a good volume of moss
Using your chosen tool you should aim to remove a good volume of moss and thatch, setting the blades/tines so that they only just brush the soil surface. You should not aim to remove all of the moss; instead rake until you can start to see some soil beneath, while still leaving plenty of grass cover which will then be able to spread out and thicken up where the moss used to be.
Scarification step 2: Apply moss killer
Now is a great time to apply your chosen moss killer when a great deal of the moss has been removed. The solution will penetrate the moss more effectively, killing almost all of the plant.
A great method would be to apply the moss killer a month or so before scarification and then a few days after, but be sure to follow the instructions on your specific brand of moss killer to avoid overdosing.
Step 3: Aeration
This is the method of introducing thousands of holes into the lawn to encourage airflow and improve drainage. A couple of different tools can be used:
Garden fork/ handheld aerator: Ideal for the small lawn you use it to plunge the tines around 2-6 inches into the soil and roughly every 6 inches apart.This will relieve compaction but can be back breaking.
Petrol aerator: The ultimate choice can be fitted with a variety of tines, usually solid or hollow core. These remove a core of soil and leave a hole ½ inch wide. This is the best method of relieving compaction and will leave holes all over the surface around 3 inches apart, but machines can be heavy and difficult to use on a small lawn.
Using your chosen method, aim to cover the whole lawn, try and work in straight lines gradually moving from one side of the lawn to the other. The cores can then be raked up or left on the surface to naturally break down.
Aeration will greatly improve airflow and drainage, which will remove the growing conditions for moss to thrive and is a great tool to prevent moss returning.
Step 4. Lawn care & treatments – moss prevention
Now that we have eradicated the moss we can try to stop it from returning. A regular lawn care program including fertiliser and weed killer will encourage the grass to spread out and fill the gaps where the moss once was.
Feed and weed the lawn
Regular feed, roughly every ten weeks from spring to autumn will encourage a healthy vigorous lawn. Which will help keep moss at bay.
Autumn Moss treatments
A moss killer applied in autumn and perhaps again in early spring may be all that is needed to deter moss in a well cared for lawn.
Correct mowing technique
Set your lawn mower blades to a height of 1- 1.5 inches from the ground. A longer leaf blade will be stronger and healthier, leading to a thicker lawn which can not easily be invaded by moss spores.
Scarification and aeration
If your lawn has species that can produce a lot of thatch or runners (stolons) a light scarify and aerate every year will help prevent the return of moss and keep it looking its best. Prevention is better than cure, a light scarify is far easier and less destructive to a lawn than removing a thick mat of moss.
Reseeding a moss covered lawn
If the moss in the lawn was particularly heavy and the bare patches are large then some seed may need to be applied afterwards as if left thin and bare moss can rapidly spread back into the open spaces.
There is no point spreading seed on top of moss. Grass seed needs to make contact with the soil in order to germinate so simply scattering seed would be a waste. For best results heavily scarify the lawn first.
Once scarified scatter a layer of seed on the bare soil, at approx 35g per m2. Bare seed will rapidly dry out so this should be covered with a layer of soil to help hold in moisture and heat. The new seed should germinate in 7-14 days but make sure it is done in late spring or early autumn when soil temperatures are 8 degrees or higher.
If this all sounds a bit too much we can take the care of everything for you. We offer a full lawn disease treatment service that will take call of all your moss and fungus. Choose from our; Standard, Essential or Ultimate plan and we will take care of the rest.