Moss Removal

To get rid of moss in the lawn start by spraying a ferrous sulphate based moss killer then remove the dead moss by raking

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 early to mid 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. Though the raking out shouldn't commence until things have warmed up on the basis you'll want to over seed as soon as possible afterwards, any application of moss killers can be done several weeks before raking commences.

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 September sun.

Suitable Products

There are primarily 2 products to use. Those containing ferrous sulphate which are our Green-up Ferrous Sulphate applied as a liquid and our Winter Green High Iron applied dry. An alternative is MossOff, which is applied as a liquid. They are all equally effective, so you decide what to use based on convenience and cost.

Moss Killing & Raking

The most common procedure is to apply a 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 (granular or liquid) 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 objective of applying moss killer in the first place!

My alternative method is:

  • Rake out the moss. You will not get it all
  • Apply a 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

Note: If applying ferrous sulphate after raking, which is to be followed by seeding, you should use a soluble product such as Lawnsmith Green-up Ferrous Sulphate NOT a dry granular one such as Lawnsmith Winter Green. This is because dry products are slower to react and may effect the seedlings.

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. If using just ferrous sulphate products, 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 moss killer or MossOff would be the preferred choice in this instance.

Moss Removal Action Plan

  • Winter Green High Iron can be substituted very effectively for ferrous sulphate if applied before raking. It is slower to react than soluble ferrous sulphate applied as a liquid and, therefore may affect seedlings if applied after raking and just before seeding
  • If applying ferrous sulphate or MossOff prior to raking, do this 7 to 14 days before. Damp conditions improve penetration into the moss if using ferrous sulphate, so if conditions are dry, give the lawn a very light sprinkling with the hose prior to application. Do not water after. Dry conditions are required if using MossOff. A light high topping with the mower beforehand will also aid penetration, whichever product you are using
  • Because moss products acidify 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 beforehand 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. If you introduce MossOff into your plan as the second treatment, then the period between moss treatments can be reduced, often making the plan more manageable and user-friendly. 
  • If you're not applying moss killer after raking then you can immediately over seed to complete the procedure. Otherwise wait 24 to 48 hours after applying ferrous sulphate, and 7-10 days after applying Moss-Off before seeding.
  • It is imperative that you remove as much moss/debris as possible to expose bare soil during the scarifying/raking process.
    This is where your seeds need to be when over seeding. Any debris left behind creates a barrier between seed and soil reducing the chances of the seed rooting and growing. Therefore run over the lawn with your scarifier and mower to clear as much as possible,
  • If you experience dry summers, have soil that is freely draining or have an older lawn then adding a wetting agent at this point is highly beneficial. It will help the soil capture and hold water more readily benefiting your lawn as it recovers. Our granular Satugran is ideal for this.
  • The next step is to over seed. You shouldn't rely on your grass to fill in the damaged areas. Adding new grasses to your lawn keeps it strong and considerably improves its vigor and looks. See also Grass Seeding Techniques to learn how to seed correctly.
  •  Always use a seasonal fertiliser after raking, scarifying or over seeding. This can be applied on the day of seeding for convenience but is better if applied once the seed has germinated. See the featured products below.
  • Any weed killing where young grass is concerned needs to be done with Weedol at least 2 months before or after seeding/germination.