Every gardener will have problems at some stage with moss on the lawn. Not only does it look unsightly, it can also be the result of poor growing conditions. Moss can be kept at bay by improving your lawn’s health and keeping it in tip-top condition.
When you’re troubled with moss on a regular basis, it’s always a sign of underlying conditions. It can be caused by poor drainage and damp conditions on your lawn. If it’s a new lawn, this may be the result of poor site preparation.
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Causes of moss
If moss appears on established lawns, causes can include poor drainage, a lack of feed, acidic soil conditions, a lack of aeration and over-use. Poor conditions encourage the growth of moss and it becomes a vicious circle.
Sparse grass cover and worn areas of the lawn, especially where children play or along walkways, can leave the grass open to attack from moss. Once the moss has taken hold, the grass won’t grow back properly until remedial action is taken, so it will get worse unless the moss is removed, and the area is treated.
Areas particularly prone to moss include shady areas beneath the trees, or patches where the soil is compacted. While wet weather and waterlogged grass can cause moss, ironically, so can drought conditions. Soils with a high clay content can dry out during a drought (or even in normal summer conditions), when the loss of moisture causes the soil to shrink.
When it becomes denser and tighter, the grass roots can tear and sustain damage. This makes it impossible for them to get the nutrients and water needed. Subsequently, the quality of the grass can suffer and this can lead to the formation of moss. Mowing the grass too close and infertile soil are other causes of moss.
Removing the moss is only the start of your lawn maintenance programme, as it will simply return if you don’t improve the underlying conditions. You can remove it either with or without the use of weed killer.
To remove it without weed killer, scarify the moss in autumn – around September and October. This means you need to carry out some vigorous raking. It’s easy to do this by hand on small lawns, but on bigger lawns, you may need to use a mechanical scarifier.
There are numerous non-chemical, bacteria-based products on the market, which are aimed at controlling moss and also feeding your lawn.
If you’re applying a moss-control product, mow the lawn first and keep it as short as possible. Then, apply the product and leave it in place for seven to ten days, before mowing again. These products are best applied between March and October. The dead moss should break down and there won’t be any need to scarify as well.
Some moss killers contain sulphate of iron – a moss treatment best applied in spring or autumn. The moss will blacken within two to three weeks and can be removed with a rake. Other moss killers are combined with a fertiliser such as phosphorus, nitrogen and potassium.
Moss killers can be applied by hand, or by using a push-along spreader. Don’t apply ferrous sulphate mixed with a carrier (known as lawn sand) at too high a rate, as this may kill the grass as well as the moss. Apply moss killer in fine weather – some varieties must be watered after 48 hours if it hasn’t rained.
Moss will be controlled, but only on a temporary basis until you resolve the underlying conditions that caused it to appear in the first place. You must now address the lawn maintenance to get your grass into better condition so that the moss doesn’t grow back.
Moss can be notoriously difficult to dispose of, especially in large amounts. It’s slow to break down, so isn’t great to use as compost, unless it’s mixed well with other ingredients. The best advice is to mix it with plenty of other ingredients – usually four times the volume of the moss. It can be very persistent, however, so even putting it in a composter is no guarantee of killing it and waiting for it to decompose. It can be stored and added gradually, with other ingredients.
Realistically, it should break down eventually, like all green things, but in practice, many gardeners report that it starts to regrow after a short time. Even when it appears to have decomposed, this isn’t always the case and it can start to reappear. The higher the temperature, the more chance there is of the moss decomposing.
To avoid the possibility of the moss spreading to other garden areas, it’s often better to throw it in the green waste bin, rather than putting it in the compost heap, to be on the safe side.
Lawn maintenance tips
Encourage lush grass growth by feeding it well and caring for it on a regular basis.
Reducing the amount of shade will help, so if there are thick trees overhanging the lawn, try having them thinned out and the height reduced to get more sunlight to the grass. In compacted areas, spike the lawn with a garden fork or a mechanical slitter to aerate the turf.
Use a multi-purpose compost to feed your lawn and avoid cutting the grass too low. If your soil is very acidic, apply garden lime at a maximum of 50 grams per square metre to reduce the acidity and discourage moss regrowth.
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