How to get rid of moss in lawns

Moss is one of the most common lawn problems in Britain. It thrives in our damp climate, creeping through lawns over autumn and winter until spring arrives and you realise half your “grass” is actually moss.

The good news: moss is easy to kill. The bad news: unless you fix the underlying problems, it will come straight back. Here’s how to get rid of moss properly – and keep it gone.

Why Moss Grows in Your Lawn

If you have moss, your lawn conditions are favouring it over grass. Moss doesn’t appear randomly – it moves in when grass is struggling. Understanding why it’s there is the first step to getting rid of it permanently.

Shade. Moss thrives in low light where grass struggles. Areas under trees, beside fences, and north-facing gardens are prime moss territory. If your lawn gets less than 4 hours of direct sunlight, moss will always be a battle.

Poor drainage and damp soil. Moss loves moisture. Compacted soil that holds water, clay-heavy ground, and areas where water pools all create perfect moss conditions. Grass roots need air to breathe – waterlogged soil suffocates them while moss flourishes on the surface.

Soil compaction. Heavy foot traffic, parking, or simply years of use compress soil particles together. This squeezes out air, prevents water draining, and stops grass roots penetrating deeply. Moss, which has no real roots, doesn’t care.

Low nutrients. Starving grass can’t compete with moss. If you haven’t fed your lawn in years, the grass becomes weak and thin, leaving gaps for moss to colonise.

Mowing too short. Scalping your lawn weakens the grass and exposes bare soil. Moss quickly fills the gaps. Keep your mower at 3-4cm minimum.

Acidic soil. While moss tolerates a wide pH range, grass prefers slightly acidic to neutral soil (pH 6-7). Very acidic conditions favour moss over grass.

When to Treat Moss

Timing matters. You need the grass to be growing strongly so it can recover after you remove the dead moss and fill in the bare patches.

Best times: Spring (March-April) or autumn (September-October). The soil is warm, moisture is usually plentiful, and grass is actively growing.

Autumn is ideal for heavy moss problems. Treat in September, rake out in October when grass is still growing but most weed seeds have finished germinating. This prevents swapping a moss problem for a weed problem.

Spring works well for lighter infestations. Treat once soil warms up (March-April), then rake and overseed. The growing season ahead gives grass time to recover.

Avoid: Mid-winter (grass dormant, can’t recover), mid-summer (drought stress, heat damage risk), and any time when grass isn’t actively growing.

Step 1: Kill the Moss

Never rake out live moss. This is the most common mistake. Raking live moss spreads the spores across your lawn, making the problem worse. Always kill it first, then remove the dead moss.

Iron sulphate (ferrous sulphate) is the most effective moss killer. It’s used by professional greenkeepers on golf courses and sports pitches. When iron sulphate contacts moss, it draws out moisture and the moss blackens and dies – often within hours.

How to Apply Iron Sulphate

Choose the right conditions. Apply when rain is expected within 24-48 hours, or water in after application. The ground should be moist but not waterlogged. Avoid hot, dry weather – iron sulphate can scorch grass in drought conditions.

Application rate for moss killing: 3-4 grams per square metre. This is higher than the rate used just for greening grass. At this concentration, moss will blacken within hours to days.

Methods:

Granular products (easiest): Scatter evenly by hand or with a spreader. Water in thoroughly afterwards or apply before rain.

Liquid spray: Dissolve iron sulphate in water (4g per litre covers 1m²) and apply with a sprayer or watering can with a fine rose. Use the solution the same day – it loses effectiveness once mixed.

Combined products: Many lawn treatments contain iron sulphate plus fertiliser, killing moss while feeding the grass. These are convenient and help the lawn recover faster.

Warning: Iron sulphate stains concrete, patios, and paths orange-brown. Sweep or blow any granules off hard surfaces immediately after application. The stains are very difficult to remove.

Step 2: Remove the Dead Moss

Wait 7-14 days after treatment. The moss should be brown or black and lift easily. If it’s still green and firmly attached, wait longer or apply a second treatment.

For small lawns: A spring-tine rake (wire rake) works well. Rake firmly to pull out the dead moss, working in one direction then at an angle.

For larger lawns: Hire a powered scarifier or lawn raker. One pass may not be enough – professionals often make two passes at different angles. See our complete guide to scarifying your lawn for detailed technique.

Expect a mess. If you had a lot of moss, your lawn will look terrible after raking. You’ll be shocked at how much material comes out. This is normal – better out than in.

Dispose of the moss properly. Don’t compost it in large quantities as it breaks down very slowly. Bag it for green waste collection or add small amounts to compost mixed with other materials. Some gardeners use it for hanging basket liners or wildlife habitats.

Step 3: Help Your Lawn Recover

After removing moss, you’ll have bare patches. The grass needs help to fill these in before moss (or weeds like dandelions and clover) return.

Overseed bare areas. Sprinkle grass seed into the bare patches. For shady areas, use a shade-tolerant seed mix. Keep the seed moist until established.

Feed the lawn. A fertiliser application after scarifying gives the grass nutrients to recover quickly and thicken up. Strong, dense grass leaves less room for moss to return.

Water if dry. New seed and recovering grass need moisture. If spring is dry, water regularly until the lawn has filled in.

Step 4: Fix the Underlying Problems

This is the step most people skip – and why their moss keeps coming back. If you don’t change the conditions that caused moss to thrive, you’ll be treating it again next year.

Improve drainage: Aerate compacted areas with a garden fork or hollow-tine aerator. Push the fork in 10-15cm deep and wiggle it slightly, working across the worst areas. Do this at least once a year. For severe compaction, hire a powered aerator or consider professional hollow-tine aeration followed by topdressing with sharp sand.

Reduce shade: Prune overhanging branches to let more light reach the lawn. Remove lower branches from trees. If shade is unavoidable, accept that you’ll need to manage moss regularly or consider alternatives like shade-tolerant ground cover.

Feed regularly: A well-fed lawn is thick and competitive. Apply lawn fertiliser 2-4 times per year – spring, summer (if not too dry), and autumn. Healthy grass crowds out moss.

Mow higher: Set your mower to at least 3-4cm. Longer grass shades the soil surface, making it harder for moss to establish.

Check soil pH: If your soil is very acidic (below pH 5.5), applying garden lime in winter can help raise the pH to favour grass over moss. Test first – only lime if needed.

What Doesn’t Work

The internet is full of “natural” moss remedies. Most don’t work, and some make things worse:

Baking soda: Sometimes recommended, but largely ineffective on lawn moss. It might work on tiny patches on hard surfaces, but for lawn moss you need proper treatment.

Dish soap: Can kill moss on contact but also damages grass. Not selective and doesn’t address the root cause. Avoid.

Vinegar: Burns foliage but doesn’t kill moss reliably. Can damage grass and soil. Not recommended for lawns.

Bleach: Will kill moss but also kills grass, damages soil, and is an environmental hazard. Never use bleach on lawns.

Stick with iron sulphate-based products. They’re proven, effective, safe for grass when used correctly, and actually benefit the lawn by providing iron. For stubborn weeds that appear in bare patches after moss treatment, a selective lawn weedkiller containing 2,4-D can help without damaging the grass.

Frequently Asked Questions

What kills moss in lawns without killing grass?

Iron sulphate (ferrous sulphate) is the most effective moss killer that’s safe for grass. It blackens and kills moss within hours while actually benefiting the grass by providing iron. Apply at 3-4g per square metre for moss control. Avoid applying in hot, dry conditions when it can scorch grass.

When is the best time to treat moss?

Spring (March-April) or autumn (September-October) when grass is actively growing and can recover after you rake out the dead moss. Autumn is best for heavy infestations as it avoids weed seed germination. Avoid treating in winter when grass is dormant or summer when drought stress is likely.

Should I rake out moss before or after treatment?

Always kill the moss first, then rake it out. Raking live moss spreads spores across your lawn, making the problem worse. Wait 7-14 days after treatment until the moss is brown/black and lifts easily, then rake or scarify.

Why does moss keep coming back?

Because the underlying conditions still favour it: shade, poor drainage, compacted soil, weak grass. Killing moss treats the symptom, not the cause. To prevent moss returning, you need to improve drainage (aerate), reduce shade, feed the lawn regularly, and mow at the correct height (3-4cm minimum).

Will lime kill moss?

No, lime doesn’t directly kill moss. However, if your soil is very acidic (below pH 5.5), lime can raise the pH to conditions that favour grass over moss. Always test soil pH before applying lime – unnecessary lime can cause other problems. Use iron sulphate to kill existing moss.

The Bottom Line

Getting rid of moss is a three-part job: kill it with iron sulphate, rake out the dead material, then fix the conditions that caused it. Skip the last step and you’ll be doing this again next year.

For most lawns, this means aerating to improve drainage, feeding to strengthen the grass, and accepting that very shady areas will always be prone to moss. Regular treatment every spring or autumn keeps it under control. If weeds like speedwell or chickweed appear in recovering areas, deal with them promptly before they spread. For more lawn problem solutions and maintenance guides, explore our complete lawn care resource.

If you’re dealing with moss on hard surfaces like patios, paths or driveways rather than lawns, different approaches apply – our complete guide to moss, mould and algae removal covers treatment options for all outdoor surfaces.