Help my lawn has a moss problem
If your lawn looks unhealthy because it has moss you have to realise that you have moss because your lawn is unhealthy!
Why is moss a problem anyway?
Once you have moss though it can cause more problems for your lawn as it actively competes for growing space with the grass and depending on conditions may win. What's more, in the dry conditions of summer (if we have any...), the moss will appear to die off leaving bald patches in the lawn - unfortunately the moss is playing possum and will (or its descendents) return in the wetter Autumn to late Spring.
What is the cause of moss in a lawn?
There are a few reasons listed below along with some specific suggestions on how to address each of these moss causes.
- Moss likes moist conditions (it is 90% water itself) and so a poorly drained lawn can be an issue.
- The solution for light to medium drainage problems is to aerate your lawn. This is discussed in our article on lawn aeration. For more serious water problems you may have to think of installing a better water run-off or underground drainage system.
- If the ground is too hard then grass may have difficulty in growing/spreading and the moss can take over.
- Again the solution is to carry out a form of aeration that will reduce the compaction of the soil, such as hollow tined forking or lifting the turf very slightly with a solid tine.
Too much thatch
- Thatch, a layer of plant material below the visible grass blades keeps a lot of moisture in. If the thatch is too thick (>1cm) it can encourage moss growth.
- The solution here is to scarify the lawn as discussed in this article on lawn scarification.
Poorly fed lawn
- An unhealthy lawn cannot compete with moss in some conditions and so loses.
- Feeding the lawn a good fertilizers once or twice a year (as needed) will allow the grass to compete better against moss growth.
Grass too short
- Different varieties of grass can tolerate being cut down to different lengths. In order to flourish the grass needs to photosynthesize and if its cut too short it can't grow properly. Again losing out to moss growth is possible.
- The solution here is to cut you lawn regularly to a height suitable for your type of grass. For most peoples lawns (ones that aren't just for show) that would be at least 2cm. Never cut more than about 1/3rd of the length off of the grass in one cutting to avoid damaging the plant.
Too much shade
- Moss doesn't like direct sunlight or heat and conversely will flourish in conditions of all day shade. Chances are the variety of grass you have isn't suited to growth under long term shade and is struggling.
- The solution is to try and reduce the shade if possible combined with over-seeding using a shade tolerant grass variety which are easy to find at the local garden centre.
How to get rid of moss?
The list above is a useful diagnosis but a general good lawn care plan is a safe bet.
- Mow the lawn to the correct height for your grass type and weather conditions and then wait about 3 days.
- Moss is easily killed using an application of sulphate of iron (aka iron sulphate). This is available in a few different forms, having a noticeable effect in a day and completely killing the moss in a couple of weeks. Whilst most forms of iron sulphate will feed the grass somewhat it is a good idea to try kill the moss and feed the grass so a complex weed, feed and moss killer may be best.
- After a couple of weeks (see moss killer instructions for specifics) you can then remove the dead moss (never leave it in the lawn as it will make the thatch problem worse) and reduce the thatch problem by scarifying your lawn either using a machine scarifier or a spring tined lawn rake.
- You can now loosen the underlying soil compaction by aerating the lawn using a garden fork, hollow tined fork or powered aerator.
- You lawn probably now has lots of bare patches but this is good as its in the ideal condition to apply more grass seed to. If the lawn is shaded pick a better suited grass seed for the conditions.
- Water very well to allow the seed to take and lawn to recover from this major surgery!
Cost of moss removal?
- Pure Iron sulphate is available in a powdered form and costs £1.25 per 100m2 of lawn treated, though it is often bought in bulk. This ideally needs to be mixed with water.
- Lawn sand is iron sulphate mixed with a sand based carrier for easier spreading and typically costs about £8 per 100m2 of lawn treated.
- All in one powders will feed and weed your lawn plus kill moss. They cost around £10 per 100m2 of lawn including a spreader and about £7 per 100m2 for re-fill packets.
- Aerators start at £10 for garden fork or hollow tined fork up to £200+ for a petrol aerator.
- Scarifiers start at £5 for a spring tine rake going up to £300+ for a petrol scarifier.
Both items can be rented for a day.
Although it is easy to apply a moss killer and eliminate moss for a while it will return unless the underlying problem(s) are addressed. These can be time consuming, costly and tiring but they are part of a more general lawn care plan anyway.
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