Moss
Why moss comes, how to remove it, how to stop it coming back, and when to leave it be.
Key points
Summary
| Cause | Fix |
|---|---|
| Shade | Thin branches; shade seed mix; or accept moss |
| Damp | Aerate; drain if it stays wet |
| Compaction | Aerate and top-dress |
| Mowing too short | Raise the blades |
| Acid soil | Test the soil; accept moss, or lime lightly if very acid |
Quick check
Why does moss killer on its own rarely cure a mossy lawn?
- Moss has become resistant to every product
- The cause, such as shade, is still there
- Moss killer kills the grass as well as the moss
- It only works on a newly sown lawn
What should you do a week or two after using a lawn moss killer?
- Water the lawn every day for a month
- Leave the dead moss in place to feed the grass
- Mow the lawn as short as it will go
- Rake out the black moss and sow seed
Which mowing habit encourages moss?
- Cutting too short
- Collecting the clippings in the box
- Mowing in the cool of the evening
- Mowing once a week in summer
In your garden
- Map where the moss is worst and note the likely cause.
- Rake the moss out of one patch and sow seed.
- Look for a branch you could thin to let more light onto the lawn.
Video transcript
Moss is the commonest lawn complaint in Britain's damp climate. It isn't a disease: it's a sign that conditions suit moss better than grass. In this lesson: why moss comes, how to remove it, and whether to fight it at all.
Moss moves in wherever grass is weak. The usual causes are shade, damp or waterlogged ground, and compacted soil. Mowing too short weakens the grass and opens the door. And moss prefers acid soil. Most lawns have more than one of these, so moss killer alone never solves it.
In spring, rake it out with a spring tine rake and put it on the compost heap, or scarify in autumn. Where moss is heavy, use an approved lawn moss killer first, never plain iron sulphate. When the moss has blackened, a week or two later, rake it out. Sow grass seed into the gaps, or the moss will simply come back.
To stop it coming back, fix the cause. Aerate and top-dress to relieve compaction, mow higher, and feed in spring for thick grass. Then look at the site: thin overhanging branches to let in light, sow a shade-tolerant seed mix under trees, and drain ground that stays wet.
Or simply live with it. In a shady, damp corner, moss stays soft and green all year, even where grass struggles. It's good for wildlife, from tiny insects to birds gathering nest material. And it saves time, money and effort. Many gardeners now leave moss in the hardest spots and keep the grass where it grows well.
This is one of 10 lessons in Lawn care through the year
The full course adds sorting drills, flashcards and a printable summary sheet for every lesson.