In recent years the winter months have been some of the coldest and wettest on record. This has taken its toll on many lawns throughout the country, as these adverse weather conditions are perfect for moss formation. There are thousands of species of moss with over 50 found to affect turf surfaces.
Mosses are primitive plants and it is quite possible they may actually be the worlds oldest plant specimens. They have no root structure to speak, as they depend on moisture being present for survival and reproduction. Moss is particularly troublesome on sites that retain surface moisture, have a low pH and suffer from excessive shade. It is regularly a problem on neglected lawns that receive little or no regular maintenance.
There are three different types of moss that affect turf.
- Mat or cushion forming – Troublesome on turf that receives close mowing, especially where scalping is a problem.
- Upright forming – Often found on drier soils where the pH is on the low side (acidic).
- Trailing mosses – Very common on lawns that suffer from water-logging and excessive shade.
Symptoms & causes of moss
Mosses take advantage of poor lawns, especially those that have been neglected with weak or bare areas. This creates an ideal situation for moss to invade. Once it gets a foothold it can quickly populate as it spreads by spores, or by fragments of the main plant.
Typical conditions that favour moss invasion are:
- Persistent water-logging and prolonged surface wetness
- Long periods of dry weather
- Acidic soil conditions
- Soil compaction
- Excessive organic matter accumulation (thatch)
- Lack of air movement
- Excessive shade and lack of light
- Poor turf maintenance
The conditions outlined above will create poor growing conditions for grass. While at the same time, will are ideal conditions for moss formation. This is why moss is common during the winter, there is generally more rainfall and there are fewer hours of daylight. Grass growth and vigour is very low as the temperatures drop, often close or below freezing point. If the lawn is thin and weak to begin with, then the lawn is likely to be covered in moss the following spring.
Prevention and control
As with most things prevention is better than the cure and that is certainly true when it comes to dealing with moss. If moss is a perennial problem on turf, then the conditions causing it need to be addresses. Adopt good lawn care practices that promote healthy turf and you will find that moss will become less of a problem. A lawn care program should include:
- Regular aeration to help relieve soil compaction and prevent water logging.
- Scarify the lawn to prevent thatch build up.
- Selective thinning and pruning to increase available light.
- Feeding the lawn at the correct times of the year, to encourage a thick coverage of grass.
- Mow at a sensible height. The closer you mow the more stress you put on the grass.
- Over-seeding the lawn during the autumn will help thicken up any weak areas in the lawn.
These practices will help encourage a healthy lawn with a good coverage of grass, which is essential for keeping moss out of the lawn.
If moss does invade then it needs treating and removing. The best time to treat and kill moss is during the spring as this is when it is most likely to be present in the lawn. It can be treated with a sulphate of iron based product, such as lawn sand. It is then left for a couple of weeks for the product to work effectively before the moss is removed with a scarifier or rake.
Once the dead moss has been removed the lawn may need a little attention to get it back into shape, as scarification can leave it looking ragged and thin. In ideal world, the area treated should be aerated, over-seeded, top-dressed and fertilised for a speedy recovery.
Hopefully the lawn should soon make a full recovery and moss can be a thing of the past. However is is important to note, that moss will return again if the underlying causes are not addressed.