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Tips on how to control Moss with Sulphate of Iron

Moss Control in Lawns Moss and Moss control in lawns is a practice normally performed in the spring lawn care months. There will soon (honest) be the first great weekend of weather when you venture out into the garden and take a good hard look at the state of the lawn. If the grass plants activity has thinned or weakened over the past 12 months, now is the time to start Moss control and eradication and some mechanical operations just ahead of over seeding the lawn to turn the tide on the moss and re populate with existing or new grasses.

Moss is traditionally controlled and killed using Sulphate of Iron. This is the constituent of lawn feeds that will always turn the moss black just ahead of scarification to remove it some two weeks following application. There is never a great quantity of Sulphate of Iron or Ferrous Suphate active ingredient in the well known brand of spring lawn fertiliser and feeds. For better moss control results, it is possible to purchase straight Sulphate of Iron in a 10 Kg tub, sufficient to treat up to 10,000 square metres that is mixed with water and will easily go through a Knapsack. It will be almost 95% Sulphate of Iron and will literally turn the moss black in front of your eyes, also adding some much needed colour to the lawn in the early spring.

It has a low cost per square metre and easy to apply as a foliar spray. It dissolves in cold water easily without the need for constant agitation. If your lawn has a moss problem and you have the method and kit available to apply a foliar iron and moss control product, then this is the one you need to use and it sells like hot cakes!

Mosses are plants, comparatively simple in structure and function and, with the Liverworts, comprise the Bryophyta family – one of the least complicated groups of the plant kingdom.

Mosses are found in very many situations, for example, on stones, tree trunks and turf. If you have moss on your lawns then it is primarily an indicator that you are not looking after the millions of individual grass plants that make up your lawn.

Where moss is a persistent problem, it often indicates some fundamental weakness in the turf and treatment with a moss killer is often only a short-term answer.

From the ‘Causes of Moss Invasion list’, it should be obvious that persistent moss problems are an indication of some fundamental weakness in a turf area. The presence of significant quantities of moss for long periods each year suggests that the turf may be excessively acid, lacking in fertilizer dressings or excessively wet with a small percentage of actual grass content.

Correcting these deficiencies will result in stronger grass growth and the moss then tends to disappear naturally because of the increased competition presented by healthy grasses.

Simple treatment with a moss-killing chemical is, therefore, often not the complete answer to moss trouble. Cultural control should always be considered first. Prevention is always better than cure.

A lawn should have nothing in it except good dense healthy desirable grasses – neither weeds nor moss.

Causes of Moss Invasion

1. A moist turf – poor drainage encourages the fern-like and tufted mosses
2. A soft, spongy sward with a thick fibre layer
3. A very dry soil, e.g. over drains, on mounds and ridges. Inadequate watering or
over-drainage encourages the upright type
4. Bare areas remaining after weeds have died
5. Cutting the grass too low
6. Diseased turf
7. Dry acid soil
8. Low fertility, e.g. deficiencies of plant nutrients
9. In appropriate maintenance
10. Inadequate or poor grass cover and growth
11. Low nutrient status
12. Neglect
13. Over-consolidation of the soil - compaction
14. Poor surface levels which may lead to scalping
15. Shade from trees, hedges and buildings and topography – north facing lawn
16. Turf that is not growing under ideal growing conditions
17. Weak and sparse turf
18. Compaction & over consolidation
19. Prolonged periods of wet weather
20. Time of year – autumn, winter and spring

For more information on Moss and Moss control.

To purchase Sulphate of Iron and other lawn treatments.

Related topics - How to Scarify a Lawn


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David Milbourne

Have treated lawn with Sulphate of Iron. Should I leave for 2 weeks then scarify? Have tried on a test area first as have around 1.5 acres with around 20% having moss. Do I need to put grass seed down once removed?

Reply: Type How to renovate a lawn in the search facility and you will come up with one of many articles we have written about it c/w a flow chart methodology of the process and timings inbetween.

Andrew Hayes

I know you say don't use on drives and patios because of staining, but I have a black tarmac drive and wonder if the staining would show? The reason I ask is because I have just bought 2kg of iron sulphate to do the job and then found your site...

Reply - do not use any soluble iron product on tarmac!


Can I use this solution on an asphalt / Tarmac driveway too?

Reply - No, it will stain.


What precautions are required for liquid iron sulphate This is for a bowling green Thank you.

Reply - mow first, follow the label, mix with warm water to dissolve, use a marker dye so you do not over apply or cut the dose rate in half and apply twice, each time at right angles to the first to ensure even accurate coverage. See the Lawn Shop at for professional grade soluble iron. It's what our guys use and will be good on a bowling green when applied for moss at 24 Kgs per Ha so typically 3.5 Kgs per each application. Half rate for greening up and not moss control.

Gordon Cochrane

What is the difference between ferromel And ordinary iron sulphate? The former appears to be in pellet form with an added conditioner (?) and the latter of course is just the raw chemical ( I am a chemist )

Reply - Not sure to be really honest and that's said after 32 years in the turf industry!


Very useful - thanks. Can you tell me if I can use iron suplhate to treat moss on astroturf tennis court or will it discolour the artificial grass?

Repy - Use The Lawn Shop MossGuard Hard Surface Moss and Algae Treatment.


Quite useful, but why doesn't it say what the dilution should be? For example, should for a knapsack spray be 25grm per litrer? or what? Vague comes to mind.

Reply - calibration is an important part of any lawn treatments. The label has the full details on it but as you ask in simple terms you need around 1.2 Kg in 15 Litres of water per 700 sqm of lawn approx. So 80grams per litre of water.

lizzy brouwers

Is Iron Sulphate or Sulphate of Iron organic?
thanks lizzy

Reply - it is a mineral product that is a by product of the steel smelting industry. It is non pesticide but you cannot say it is organic.

Paul Scott

What precautions should I take with children and pets after spraying moss with Iron Sulphate?

Answer - Keep all Children and Pets off the lawn for at least 12 hours.

Jenn R

We have a lot of moss and thatch and usually cut grass as short as can then apply Ferrous sulphate to kill moss. Does the grass need to be scalped short "before" applying this or can it penetrate fine with the grass long and thick then scalp it short after the moss killer works to help remove all the dead moss?

Reply - mow the lawn down as low as you can then apply the soluble iron, also known as ferrous sulphate. Then scarify etc. Type Lawn Renovation into the Blog for a renovation process and method article.

The Lawn Shop sells the Soluble Iron or Ferrous Sulphate in 2.5 Kg, 5.0 Kg and 10 Kg. Good luck!

Ronnie Hemphill

Could someone advise on how much sulphate of iron(grams) do you mix with say 10 litres of water and over what area of lawn should this quantity be applied. Thank you.

Reply - it depends upon the strength of the product as in percentage of iron in the product but work on around 1.2 Kg to 1.5 Kg of product in 15 Lts of water per approx 700 - 800 sqm. See The Lawn Shop at to purchase Soluble Iron.

Mike Seaton

Martin. Do not use Soluble Iron on any hard surface as it will cause an orange stain. Use an approved hard surface moss and algae removal product on hard surfaces.

martin j

can i use sulphate of iron on a cobbled area that is covered in moss, have used algicides but worry about run off ?

John Maling

Where can I purchase a tub of sulphate of iron to treat moss in a lawn?

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