Bowling Green Maintenance: FAQ 14. How do we get rid of moss from our green?

The moss has found conditions which are suitable for its establishment and might be thriving in these.

A dense hard wearing grass sward will provide a competitive situation in which the moss will struggle to gain a foothold, let alone thrive. So, the grass species have become weakened in some way and with reduced competitive ability have enabled moss to encroach into the green.

There are many conditions in which moss will invade and then thrive within a bowling green, however, common features are that of a thinning, weaker grass sward which has surface compaction, a lack of available nutrients within a soil, a sward which has been too closely mown, especially over long periods of time and not just occasionally for tournaments, extreme soil acidity, overapplication of irrigation – particularly where annual meadow grass is the dominant grass species, over-rolling of a sward, lack of scarification and verticutting, as well as lack of aeration activities, excessive shade conditions, especially over the autumn and winter period and a moisture retentive soil. Typically, there will be range of these features and conditions which have contributed to the moss invasion.

Eliminating moss isn’t a matter of trying one or two activities but rather finding out the underlying cause otherwise it is highly likely to be a temporary fix. Carry out a thorough investigation into the condition of the green (by doing a performance quality assessment) and gather data on the maintenance activities which have taken place. Can a cause-and-effect relationship be determined between some of the activities, materials applied (or not) and the conditions found?

You should be able to find a number of probable issues which are contributing to the moss problem and a systematic rather than piecemeal approach will be needed to tackle it.

Improve the grass growing conditions – this is the key - so that the grass can out compete the moss, by considering some of the following (these will depend upon the actual conditions found on site though):
• aerating with a solid or hollow tine fork or machine.
• apply a sandy top-dressing to help keep the surface free draining.
• remove moisture retentive thatch.
• does the area need draining, or major renovation works?
• improve soil biology, by adding organic products such as seaweed extracts, biostimulants, or similar.
• test the soil for pH and nutrients to ensure an appropriate feed is given; it can be difficult to raise the soil pH in a substantial way, so be careful not to try and change the pH measures to any great extent.
• cut back over-hanging branches, thin trees, shrubs and hedges to improve light contact on the grass sward and also to improve air circulation.
• scarify to keep the surface open.
• remove leaves (by raking or sweeping) as soon as practical from a grass surface in the autumn.
• brush the surface during the autumn and winter to keep the grass blades more upright and the sward more open for air movement amongst the leaves.
• keep an eye on your grass surface and monitor its condition throughout the year.

See the more detailed article on Moss.