Plant Doctor Archive

Gathering moss

OUR lawn is almost covered in moss. We tried spreading lime on it last year but it doesn't seem to have helped.

MOSS grows most strongly in cool, moist conditions, so it can be really bad by the time spring arrives. Unfortunately, lime doesn't necessarily help and too much may even raise soil pH to the point where it suppresses grass growth.

Moss spores are everywhere and take advantage of bare patches in lawns. Moss growth is a symptom that all is not well with your lawn and that grass growth is poor. Waterlogged soil in winter, drought in summer, pests such as grass grub and crickets, mowing too short, shading from nearby trees or buildings can all contribute to poor grass growth which allows moss to take over.

This is a good time of year to tackle the problem. First, get rid of as much of the moss as possible. You could simply rake it up or apply a moss control agent such as Moss in Lawns, Yield Moss Control or Moss Killer. Follow the label recommendations carefully and after a couple of weeks you should be able to rake out much of the dead moss.

Then do what you can to encourage strong grass growth. If winter drainage or soil compaction is a problem push a fork deep into the soil going down at least 15-20cm, and rock it a little to break up the soil deep down. Do this every 10-15cm or so across the lawn to allow excess water to drain away and air to penetrate to the roots. You could brush sand across the lawn and into the holes to keep them open. Sow fresh grass seed in the bare patches after breaking up the soil. Once grass is established, you could apply lawn fertiliser over the whole area to encourage strong growth. Prune trees to let as much light as possible through to the lawn. And don't mow too short, especially in dry summer conditions, as this can weaken the grass severely giving bare patches that will be colonised by moss in autumn.

Reproduced with permission from the former Weekend Gardener magazine. The views expressed here are not necessarily those of the RNZIH.