Tips on controlling lawn moss with Sulphate of Iron

In my previous post When to Scarify your lawn, I emphasised how important it is to remove dead grass, thatch and lateral grass growth in your lawn.

Too much thatch and lateral grass means the that the desired grass has to work very hard to push through and reach the air and also absorb sunlight.

Sunlight is essential for Photosynthesis to take place and if your grass has to work too hard it will weaken and non desirable grass species start to colonise as well as moss.

Moss is often wrongly described as the cause of a poor lawn. In fact moss has colonised as a result of a poor lawn. Keep your grass growing strongly and moss is incapable of competing and should never be a problem.

Good aeration is essential but sometimes, for reasons that are out of your control, moss will start to creep into your prized sward. One simple treatment is the application of Sulphate of Iron to suppress the moss.

The common moss in many lawns is Springy Moss which is 90% water - Sulphate of Iron will quickly expel the water and allow the grass to strengthen.

After an hour the moss will start to go black and after two days the grass will turn extremely green.

Always try to apply Sulphate of Iron on a dry still day but with rain imminent within 12 hours. The water will quickly dissolve the Sulphate and stop the grass from scorching. Once the moss starts to die back you can scarify out the debris.

Some thoughts on Sulphate of Iron.

Some people refer to it as Iron Sulphate - either or really.

The material is very fine and will easily blow everywhere if applied in windy conditions so be very wary and try only to do this job on a still day because it can readily scorch any soft tissue on plants close to the lawn.

Do not rely on the gate calibration and always follow a simple calibration method as I described in the post calibrating a fertiliser spreader.

Do not try to store Sulphate of Iron through the winter. It will attract moisture and can become lumpy and unworkable using a drop spreader - try to buy just enough for your needs, although you can use sulphate of iron throughout the winter provided the grass is not frozen.

If you do find yourself forced to use material that cannot be distributed through a spreader then it is possible to apply as a solution. Measure out the required amount of material and water that is needed if you wish to apply as a liquid, add the sulphate of iron to the water and stir until all of the lumps are dissolved - let stand overnight.

The following morning, sieve out the liquid using a funnel and old stocking. You will have noticed that there will be residual powder at the bottom. This can still be used later, now calibrate your sprayer and apply the iron solution to the lawn.