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Articles within the Moss Control and Removal Category

Unfortunately, if your lawn is prone to moss it will only get worse to the point where you have little or no grass left. You are, therefore, going to have to do something to tip the scales in favour of the grass.

Sprayers for Liquid Moss Killer

Some basic equipment is going to be required for spraying your moss killer. The size of the lawn and the cost are the deciding factors. Used correctly they can all be equally effective so the choice is yours.

Watering Can

  • Very cheap so get two!
  • Get a different coloured one just for use with weed and moss killers. No danger of killing your beloved begonia with ‘weed killer’ contaminated water!
  • Use a weed and feed killer sprinkle bar NOT a rose
  • Simple and easy to use
  • Perfect for lawns up to 200 square metres
  • If time isn’t an issue then there is no limit to the size of lawn – a lot of refills though!

Knapsack Sprayer

  • Very easy to control
  • Perhaps the quickest and most cost effective way to spray the lawn
  • Can be used for liquid fertiliser, weed and moss control on any sized lawn
  • Perfect for large lawns as it sits comfortably on your back
  • Minimal maintenance required
  • Can also be used for spot spraying lawn weeds

It is a false economy to buy cheap DIY knapsack sprayers:

  • Buy a Professional one, it’ll last a life-time
  • Your grass depends on consistent operation – better live moss than a dead lawn!
  • Spares are always available
  • Built to withstand bumps and bangs
  • A ‘pressure control valve’ is a valuable addition to any sprayer
  • Spray nozzles are interchangeable for spraying with different spray volumes or using different spray patterns for different applications

Compression Sprayer

  • Professional ones will last
  • A little awkward to pump up pressure whilst carrying
  • If not kept constantly pressurized output changes
  • For small lawns only OR spot treating large areas
  • Minimal maintenance required

What to do After Getting Rid of Moss

After any invasive treatment you should always assist the lawn to recover. This is easier if you’ve been wise with your timing and nature is helping by providing some warmth, sun and rain to speed things along.

As far as I’m concerned the lawn is there for my benefit and I want it to look respectable all year round. You should be able to achieve the same regardless of whether you’ve got a kiddies play lawn or a masterpiece. Just get your timing right!

Firstly, if you have or had moss in the lawn a dose of ferrous sulphate based moss killer, applied by watering can or sprayer after raking will kill any moss left in the lawn. It should penetrate deeply into the moss now that you’ve thinned it with your raking. This is one of the best ways of reducing moss infestation. If you applied ferrous sulphate prior to raking ensure at least 4 weeks between applications.

Secondly, get some fertiliser into the lawn. I always use a fertiliser containing potassium (all Lawnsmith fertilisers contain potassium) as this helps the grass fight off the stress of the raking and will help protect against disease.

Thirdly, add lawn grass seed. If damage is patchy then a light sprinkling (10 to 20 seeds per square inch – no more) into those areas may be all that is needed. However, if you’ve done a thorough de-mossing or de-thatching then it’s risky to expect a full and uniform recovery so get some grass seed into the whole lawn. The fertiliser will help the new seedlings but if the area you are seeding is virtually bare you could even use a pre-seeding ‘STARTER’ fertiliser which gives an extra bit of wumph to new seedlings.

If you’re going to be using iron sulphate or an iron fertiliser AND over seeding then put the seed in at least a couple of days afterwards. Other fertilisers can be applied at anytime but preferably just before or at the time of seeding.

Finally, pray for gentle rain and be prepared to get the sprinkler out if you’re the unlucky sort!

Moss Removal

Raking is the preferred method for removing moss. For small lawns a wire ‘spring bok’ or fan rake will do but it’s much easier with a hand lawn scarifier. For larger lawns a powered lawn raker or scarifier with wire tines would be best.

Good Timing helps Lawn RecoveryLawn Scarifier

Moss produces spores generally in April. In Eastbourne it will be early, in Lanark it’ll be late and in Malvern the middle part of the month; as a rule, but not guaranteed! It spores again in September. Therefore, doing the business before sporing, if possible is generally a good idea.

‘If possible’ can be a problem though. When performing any ‘invasive’ treatment to the lawn we need the lawn to be able to recover and repair itself in as short a time as possible afterward. If it doesn’t then you may swap a weed problem for your moss problem! Not a good idea, so this means warmth, fertiliser and moisture must be available to get the grass recovering.

Therefore, leaving the raking until April (but before sporing) allows things to warm up a little. There is usually plenty of moisture around and the timing will be right for a fertiliser application afterwards.

In autumn, just wait until the rains start. This will fire off the moss but will also mean the grass can recover with the rain and late September sun.

Moss Killing & Raking

The most common procedure is to apply a ferrous sulphate based moss killer to kill the moss, wait a couple of weeks and then rake the moss out. The reasoning is that you can spread the moss to other parts of your lawn if it is alive thus causing an even bigger problem.

Some considerations:

  • If you have a moss problem then the chances are good there are spores and possibly moss all over the lawn, so raking isn’t going to spread it to new areas
  • Applying a moss killer product to the lawn will never kill ALL the moss. Some moss may be too deep for the treatment to penetrate all the way
  • When you rake you will now spread this remaining live moss around partially defeating the object of applying moss killer in the first place!

My alternative method is:

  • Rake out the moss. You will not get it all
  • Apply an iron sulphate based moss killer to the moss that remains after raking. The moss will now be thin enough to allow better penetration of the moss killer
  • This method will get in excess of 90% of the moss

Perhaps the real benefit of applying a moss killer prior to raking is that the moss killer will desiccate the moss to some degree thereby reducing its bulk. So, if you have a bad enough problem applying a moss killer before and after raking may be very beneficial. Allow several weeks between treatments with the applications being made in cool wet conditions otherwise you will start to blacken the grass. In addition ensure your moss killer is low on fertiliser (nitrogen) content as a double application may cause growth or disease problems. Straight iron sulphate based moss killer would be the preferred choice in this instance.

Moss Removal Action Plan

  • If applying ferrous sulphate prior to raking do this 7 to 14 days before – damp conditions improve penetration in to the moss. A light high topping with the mower beforehand will also aid penetration
  • Because ferrous sulphate acidifies the soil you MUST use it uniformly over the whole lawn otherwise you will create pH variations which will affect grass growth and may even increase moss infestations in future years.
  • Rake out the moss on a dry day normally April to early May when the grass is noticeably growing (and late August or early September if raking end of season). Mow the lawn reasonably close before hand to better expose the moss and reduce resistance on the rake
  • If applying ferrous sulphate after raking do it straight after raking and ensure all debris is removed first. Using a rotary lawn mower to suck up the last few bits can be a good idea If applying ferrous sulphate before AND after your timing needs to change as applying high doses of ferrous sulphate less than 4 weeks apart can damage the grass. Therefore, if you are planning to spray before and after, spray 3 weeks before raking and re-spray 1 week after. If in doubt use a reduced dose (3g/m2) on the second spray
  • Follow our recommended post raking lawn recovery procedure on the next page

What is Ferrous Sulphate?

Ferrous or iron sulfate (also spelled sulphate) is a constituent of garden and lawn moss killers and some fertilisers. It is exactly the same chemical compound regardless of how it is sold or used. They may vary slightly in concentration and be mixed with other compounds but apart from that they are the same.

Ferrous or Iron Sulphate as Moss Killer

If ferrous sulphate is to be sold as a moss killer then the law requires that it is covered by pesticide legislation plus extra health and safety measures just as any pesticide should be. This adds to the cost!

This enables the manufacturer to advertise the product as a moss killer and give directions for its use to achieve moss control. The concentrations are high enough to kill moss and low enough to cause the grass little or no damage. You will find these commonly sold as:

Moss Killer

This is either straight ferrous sulphate or perhaps with a little fertiliser added. Just basic ingredients and nothing unique or particularly scientific.

Lawn Sand

This is another method of applying ferrous sulphate to kill moss. This is just ferrous sulphate, with a dash of nitrogen fertiliser all mixed with sand to facilitate easy spreading.

If you have ever used Lawn Sand you may have experienced severe lawn damage as well. Unless kept dry, applied in the right conditions, evenly and at the correct dosage you can defoliate your lawn in days! I rarely use Lawn Sand because of this so unless you have the experience and confidence I suggest you give Lawn Sand a miss.

Ferrous or Iron Sulphate as Fertiliser

Ferrous sulphate as a fertiliser is the same stuff but sold for different purposes – usually for greening grass and hardening against frost and disease. The concentration to achieve this is usually lower than if used as a moss killer but pretty much every knowledgeable gardener and green keeper knows that it will do the same job as a moss killer at its higher permitted application rates.

Because it is not sold as a moss killer it is not required to be certified as a pesticide. This means it is cheaper but the benefit of being able to sell or market it as a moss killer is lost.

Granular Fertiliser

There are excellent winter fertilisers available that have very high iron content which cause blackening such a Lawnsmith® WINTER GREEN. These pass nicely through any fertiliser spreader and therefore pose no spreading problems. This is a slightly more costly iron option but the time saved, together with the fertiliser content easily make up for it.

If you like things as ‘hassle free’ as possible then this is the method for you: just follow the application details on the product. Rates at the upper end of the application rate scale will cause blackening.

Soluble Iron

You can also buy soluble iron or ferrous sulphate ‘as is’ and apply through a watering can with a weed & feed sprinkle bar or by knapsack sprayer. It is easy to get concentrations right, simple to apply, value for money and beneficial for the grass. Low concentrations give the lawn a superb green-up whilst higher concentrations ‘harden’ the turf against disease. Rates at the upper end of the scale will cause blackening. This is how most sports and commercial users apply ferrous sulphate whether as a fertiliser or moss killer. See the next page for more detail.

Moss Killer for Lawns

Using a moss killer is the next weapon to bring about a better lawn. Over the next few pages we will discuss the various ways you can control, kill and remove moss.

You can use moss killer as a standalone treatment to inhibit growth or as part of a moss removal programme. If the moss is not too overwhelming you can often keep it at bay or even reduce its spread by regular use of a moss killer.

Sulphate of Iron

Lawnsmith Green-Up Ferrous Sulphate
For all intents and purposes there is only one compound available that kills moss in lawns - sulphate of iron; also known as iron sulphate. Its chemical formula is FeSO4. It is the moss killing component of moss killers and lawn sand and is commonly sold in the green keeping industry as a fertiliser under the name of Ferrous Sulphate or Soluble Iron. It may also be combined with other elements and can therefore be used as a general fertiliser. Our high iron winter fertiliser called Winter Green is such a product.

The most common way of applying a ferrous sulphate based moss killer is to spray it in solution a week or two prior to raking out the moss. The moss is partially desiccated and is thus easier to remove. However, there are two other opportunities to use it that may make getting rid of moss easier and more efficient.

Use for Moss Suppression

Firstly we can use it to inhibit moss growth so that we enter spring with considerably less moss had we not taken action. By applying your iron sulphate moss killer, usually by sprayer or watering can during the moss growth period, anytime from late autumn through to spring you will at least kill the exposed upper layer of moss. Though iron sulphate is brilliant at killing moss it has its limitations when the moss is very deep. It will only penetrate 1 to 2cms into the moss so if you’ve got more depth than this the moss underneath may well remain alive. Therefore, if you know your lawn is prone to heavy moss infestations, starting your treatments in October before the moss gets too deep will be beneficial.

Even though the bottom layer of moss may remain alive, the killing of the top layer will stop light getting to the living bottom layer and the progress of the moss will be halted for perhaps 6 to 8 weeks. This is an easy and cost effective approach to moss control without the need for removal by raking, particularly if your lawn is not smothered. This treatment can be repeated every 4 to 8 weeks over the winter months.

If at the same time you have improved the local environmental factors a little, together with improved lawn care practices, you may well have made conditions more favourable for the grass. This together with a moss killer could bring about the desired result. If not, then the moss will have to be removed. See Moss Removal.

Use for Getting Rid of Moss

Secondly, you can use it after removal of the moss in the spring. Treating moss prior to removal will not kill all the moss; perhaps 20% to 50% will remain to re-infest your lawn. Therefore, if you treat what remains after raking you may well acheive upwards of 90% moss control. Ensure at least 4 weeks between applications if you are applying before and after raking. If you are overseeding, do this at least 24 hours after applying your moss killer.

Moss Killer Warning

Because ferrous sulphate acidifies the soil you MUST use it uniformly over the whole lawn otherwise you will create pH variations which will affect grass growth and may even increase moss infestations in future years.


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