Sulphate of iron, iron sulphate or ferrous sulphate has a number of uses on the lawn. It is relatively cheap to buy and can be used as a lawn green up, a worm suppressant, a turf hardener against disease, but its main role is as a moss killer. It can be applied to the lawn on its own or more commonly, as a mixture of ingredients in products like lawn sand or weed, feed and moss killer products.
Iron sulphate can be applied at most times of the year, spring being the most common time, as this is when moss treatment is often carried out. However, frequent applications (every 6 – 8 weeks) from late autumn, through the winter into early spring will certainly help prevent moss from forming during this time.
Used on its own and applied at a rate of 10 grams per square meter, sulphate of iron kills moss very quickly, however, the duration of kill is relatively short. This is why the moss is removed from the lawn shortly after treatment.
How to apply sulphate of iron
Sulphate of iron is a powdered product and can be applied through a spreader i.e. lawn sand, alternatively it can be applied through a sprayer or watering can as it is soluble in water.
- Spreader – A spreader should be used if you are applying a powder / granular form such as lawn sand or weed, feed & moss killer. Split the product into half rates and apply it to the lawn doing two separate passes (the second pass at 90 degrees from the first). Although you could apply it by hand, a certain degree of skill and experience is required to get an even coverage. When the product has been applied with a spreader it is important to stay off the lawn until it has been watered thoroughly. As with most granular moss killer products water in if no rain has fallen within 48 hours of applying the product.
- Sprayer – If you intend to use sulphate of iron on its own then spraying is the best and easiest option. The product is mixed in water (it mixes better in warm water but is not essential) and then simply sprayed on to the lawn. It needs to be mixed well to prevent spray filters and nozzles clogging, this is where the warm water helps the iron dissolve quickly.Do not spray iron sulphate if rain is imminent, as it needs to dry on the moss for the most effective results. Once applied, no watering in is required with this method of application.
Tips for tank mixing sulphate of iron
- Use protective gloves when handling to prevent irritation and staining to hands.
- Wear protective goggles of glasses to protect eyes from splashes.
- Mix the iron in a separate container and transfer to sprayer.
- If possible mix in warm water, this will help the product dissolve quicker. Stir well until thoroughly mixed.
- When pouring the mixture into the spray tank, take care not to tip the impurities in the bottom of the container that haven’t dissolved, into the spray tank. If the sprayer has a filter, use it to remove any particles that can cause blockages.
- Take care when mixing as any spillage will stain concrete paths and patios a rusty brown colour, that can be difficult to remove
- Wear old clothes or overalls as iron will stain them too. Wash them separately, as they may stain other clothing if washed together.