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 & Lawn Recovery
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.
- 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