• Iron Sward iron sulphate moss killer and lawn greenup by Mowd
  • Iron Sward granular iron sulphate lawn treatment
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Iron Sward Moss Killer & Lawn Greenup 12%Fe + 5% Mg

Iron Sward Moss Killer & Lawn Greenup 12%Fe + 5% Mg

Year-round (avoid frost) feed

Deepen the green. Kill the moss.

£8.47
£8.47
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  • ✓Kills (blackens) moss ready for scarifying or raking out
  • ✓Rapidly greens up the lawn
  • ✓Hardens the lawn against winter stress
  • ✓Provides protection against hard frost

We match the pack size to your lawn — just choose your area above.

Measure your lawn · or estimate: small ≈50m², medium ≈150m², large ≈300m².
Good to know
  • ✓Suitable for moss control & deep green colour
  • ✓Keep children & pets off until watered in and dry
  • ✓Apply in Year-round (avoid frost)

UK-made seasonal feed · Slow-release · also available on a Lawn Plan

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Iron Sward is an iron sulphate lawn treatment that kills moss and rapidly greens up your lawn, with added Magnesium for a deep, lasting colour.

Nutrients, coverage & application

Coverage & application

Coverage
~28–40 m² per kg
Application rate
35 g/m²
Season
Year-round (avoid frost)

Nutrients

NPK 12% Fe + 5% Mg (iron sulphate)

Iron (Fe) 12% + Magnesium (MgO) 5%

Blackened moss dying on a lawn after iron sulphate treatment

Kills moss

Even at normal application rates, with 12% Iron, Iron Sward iron sulphate blackens moss so you can rake or scarify it out. It works quickly too - moss starts to turn black within 4 days and is ready for scarifying within 2 weeks.

Deep, intense green lawn after iron and magnesium treatment

Intense green lawn

More than just Iron, the added Magnesium teams up with the iron sulphate to produce a deep, intense green lawn. You'll start to notice the difference in just 4 days, and it lasts over 6 weeks.

Family enjoying a picnic on a hardy green lawn

Provides a hardy sward

Iron is essential for a hardy sward that's resilient to disease, stress and heavy use. Want a lawn that's family-friendly and looks great? You need Iron Sward.

Frosty lawn kept hardy and green through winter

Supports chlorophyll synthesis

Iron is a nutrient that doesn't move around the grass plant very well, so regular applications are essential to prevent chlorosis (the yellowing of the grass leaf) and keep your lawn looking vibrant green.

Why Mowd?

Right feed, right time

Seasonal formulas matched to what your lawn needs now — not a one-size-fits-all box.

Slow-release, less waste

Controlled-release feeds steadily for up to 3 months, with fewer nutrients lost to leaching.

Made by turf pros

Built on 40+ years of sports and domestic turf experience, blended and bagged in the UK.

Help when you need it

Plain-English guidance, the free MyLawn app and UK-based support if you ever get stuck.

Ready to feed your lawn this summer?

Pick your lawn size for the exact amount you need - or let a Lawn Plan do the timing for you.

  • ✓The right treatment auto-delivered each season
  • ✓Never miss a feeding window or run out
  • ✓Better value than buying treatments one by one

Frequently asked questions

What is the difference between granular and liquid iron sulphate treatments?
Liquid Iron can green up the lawn in as little as a few hours, but typically lasts only 1-2 weeks. Granular iron sulphate can take a few days to show its effects but lasts 4-6 weeks. The most interesting difference is with moss - granular treatments penetrate moss much deeper and reduce the need for multiple applications. Iron Sward is a granular treatment lasting 4-6 weeks and is highly effective at sustaining green-up and moss control.
What does the added Magnesium do in this iron sulphate treatment?
The addition of Magnesium enhances chlorophyll production to give your lawn a deep, vibrant green colour. The homogeneous granules ensure an even colour distribution, even when applied at a lower rate.
When can I apply this iron sulphate lawn treatment?
Iron sulphate can be applied at any time of year, providing there is no risk of frost. Water in well if no rain is expected.
How long does this treatment last?
Iron Sward iron sulphate lasts 4-6 weeks per application. Iron doesn't move freely in the grass plant, so regular applications are recommended.
What happens to moss after I have applied an iron sulphate treatment?
Iron sulphate kills moss, turning it black and crispy. Once the moss is dead (after around 2 weeks), you can remove it with a rake or scarifier. It's worth seeding the areas you've cleared to stop moss returning. If the area is prone to moss, address the root cause too - improve drainage and sunlight access, and use a lawn seed more resilient to shade.

What lawn owners say

4.6/5 on Trustpilot · 62 reviews · read our reviews →

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