Which Lawn Moss Killer to use and When

There are a variety of moss killers on the market each having their own particular benefits. The most flexible and useful ones are:

• Ferrous sulphate applied as a liquid
• Ferrous sulphate with fertiliser applied as dry granules
• MossOff chemical free applied as a liquid

These moss killers can be problematic:

• No rake products – have cultural downsides and take too long to work if you need to over seed
• Lawn sand – very effective but can burn the lawn if not used carefully. We suggest this is for professionals or people with experience.

So lets take our best three and use them in various ways to maximise control of moss.

Winter Moss Suppression

Moss starts growing as the rains start in late autumn. It will grow rapidly from October onwards in the cool dull conditions and take advantage of the fact that grass growth has slowed. This also means you shouldn’t rake the moss out until the grass starts growing again in spring.

The great news is that you can still use a moss killer without having to rake the moss out. Just use your preferred moss killer as and when required to kill the top layer of moss which prevents light reaching the actively growing parts. This will stunt the growth of the moss so that you enter spring with considerably less moss than if you hadn’t followed this process.

The best moss products to use for this are:

Lawnsmith Green-up Ferrous Sulphate

Cheap, easy to use and can be applied every four weeks. It will also green the grass without causing growth, harden the grass against disease and reduce worm casting.

Ferrous Sulphate with Fertiliser – Lawnsmith Winter Green

As long as the fertiliser is low in nitrogen and high in potassium the effect will be the same as above but with improved greening of the grass. This is ideal if you prefer a dry product or if the lawn needs a nutrient boost due to a mild or wet winter.

MossOff Chemical Free

Though ultra-safe for children and pets it is rather expensive to use for moss suppression particularly as ferrous sulphate products are very safe and the lawn is unlikely to be used during winter.

Spring or Autumn Moss Control without Moss Removal

You are likely to just apply a moss killer if the amount of moss is very low. This would be typical in spring or early autumn particularly if you had also been suppressing moss as above. The best products for this are:

Lawnsmith Green-up Ferrous Sulphate

This is a very useful product as it is also beneficial for the grass (iron stimulates green colour) and suppresses worm casting to a degree. You will still need to feed the lawn as normal as ferrous sulphate is not a nutrient feed.

MossOff

Also very useful in this situation as it has a residual effect and suppresses moss for several months after application

Lawnsmith Winter Green and Miracle-Gro Mosskill

These are useful in spring but are no substitute for a spring fertiliser application so if using ensure at least 4 weeks between the applying these and the spring feed

Moss Control with Moss Removal – Medium Infestation

Remove as much moss as possible then apply any of the moss products mentioned. Wait the required period, rake out the now dead moss that remains, over seed and use a spring fertiliser once the seed has germinated.

Moss Control with Moss Removal – Heavy Infestation

Treat as above but apply moss killer before removing moss as well as after.

This has the additional benefit of killing and desiccating some moss making it easier to remove. This does increase the time taken from start to finish as follows:

Green-up Ferrous Sulphate

This is perfect as it only takes a day to work which means you can get on with removing the moss early. However, if you are using the same product a second time (after raking) you are best to give a 4 week gap between applications.

Lawnsmith Winter Green 

Ideal for use before removing moss as it will start killing the moss without causing too much grass growth. As for ferrous sulphate above a 4 week gap is needed if following with a second application of a product containing ferrous sulphate.

MossOff

Because one of the main benefits of this product is the residual moss suppression it is best used after raking so that the spray coats the soil. This then means you can used ferrous sulphate on day 1, remove moss on day 2, use MossOff on day 3, do a final tidy up on day 10-12 and seed on the same day.

Over-Seed and Fertilise

Once you have finished with moss control applications and removed the moss always over seed and once germinated apply the appropriate spring or autumn feed.