If you’ve been wondering how to overseed a lawn full of moss, you’re absolutely not alone. A mossy lawn can feel like a gardening failure, but it absolutely shouldn’t. More often than not, it’s simply a sign that the grass is struggling.
Yes, moss thrives where conditions suit it, and while many gardeners rush to remove it, moss isn’t always a problem. In fact, this misunderstood plant actually works wonders to stabilise soil and support soil life, all while thriving and adding a splash of green to those shady spots where grass won’t.
It doesn’t need mowing, watering or feeding, and in some gardens it can be a perfectly valid alternative to bare patches. Still, if you want to get rid of moss in your lawn and encourage grass to take over, overseeding can help… if it’s done properly.
How to overseed a lawn full of moss
Keen to overseed that mossy lawn? Well, hold on, because scattering seed over moss rarely works; grass needs light, air and healthy soil to establish.
‘Moss usually grows where the soil is compacted, shaded or poorly drained,’ explains Morris Hankinson, director of Hopes Grove Nurseries. ‘It will also thrive in acidic soil or where fertility is low.’
Remember: grass needs healthy soil to grow, so moss is often a symptom rather than the cause. Take care to figure out what the issue is with your lawn before you start overseeding, then, or your efforts won’t last long…
1. Remove the moss
‘Raking and scarifying moss is the best environmental option,’ says Morris. ‘It also loosens the soil surface, which helps seeds germinate.’
Organic moss removers are another option, but always check they’re safe for wildlife, pets and children. ‘Raking and scarifying moss is the best environmental option,’ says Morris. ‘It also loosens the soil surface, which helps seeds germinate.’
Organic moss removers are another option, but always check they’re safe for wildlife, pets and children.
2. Allow light through
If you want to overseed a lawn full of moss, Morris says the most important thing to do is let as much light in as possible.
‘If possible, prune trees or anything casting heavy shade,’ Morris advises. ‘Grass needs sun – moss doesn’t.”
3. Aerate the soil
Next on the agenda, if you want to overseed a lawn full of moss? Aerate, aerate, aerate!
‘Compacted soil needs aerating to increase oxygen flow and support beneficial soil organisms,’ Morris says.
Use a garden fork or aerator to make holes across the lawn, then top-dress with a thin layer of good-quality peat-free compost to improve structure and drainage.
4. Sow grass seed
Obviously, you’ll have to apply grass seed at some point.
‘Choose a high-quality, untreated seed,’ Morris recommends (we rate Miracle-Gro EverGreen Shady Lawn Seed, from Amazon for this), ‘and make sure it’s suitable for shade if needed.’
Mow first, rake to expose soil, sow evenly, then lightly rake and top-dress with compost.
5. And water correctly
It may sound counterintuitive if you want to overseed a lawn full of moss, but moisture is absolutely key to success.
‘For grass seed to germinate, it must stay moist,’ Morris explains. ‘Water lightly and frequently until established, then less often but more deeply.’
And if moss keeps returning? ‘It may be that nature is telling you something,’ Morris adds: perhaps moss is simply better suited to that space.
FAQs
Can I put grass seed over moss?
While you can scatter grass seed over moss, but it’s very unlikely to work well. ‘Moss forms a dense mat that prevents good seed-to-soil contact, which is essential for germination,’ says Christopher O’Donoghue, director of Gardens Revived.
‘Grass seedlings need light, air and access to soil nutrients, all three of which are conditions moss simply doesn’t provide.’
With this in mind, then, successful overseeding depends on preparing the soil properly, not just adding seed. Take care to rake back moss and loosen the surface before you begin the process, as it will dramatically improve results.
Should I kill moss before overseeding?
You absolutely do not need to chemically kill moss before overseeding, and in most gardens it’s better not to.
‘Raking or scarifying moss out is usually enough to get rid of moss, and has the added benefit of opening up the soil surface for seed to settle into,’ says Christopher O’Donoghue, director of Gardens Revived.
Morris Hankinson of Hopes Grove Nurseries recommends tackling the underlying causes of moss (is it compaction, shade, poor drainage or low fertility?) rather than focusing solely on removal, as moss will simply return if conditions haven’t changed.
Now that you know how to overseed a lawn full of moss like an absolute pro, you have a choice: will you opt for a traditionally grassy garden, or swerve into the left-field and try a verdant mossy lawn worthy of fairy visitors instead?
Whichever you go for, may the odds be ever in your favour.
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