To use Ferrous Sulphate as a moss killer, the chemical is usually mixed with water to form a solution. To begin with use a ratio of approximately 10 gms Ferrous Sulphate/1 litre water but if this does not produce the desired effect, a ratio of 50 gms Ferrous Sulphate/1 litre water can be used. The solution can be sprayed or watered on the area of grass to be treated although it is advisable to test a small area first.
An application rate guideline is approximately 5 square metres for every litre of chemical solution mixture. Be careful to avoid spraying the solution onto other garden plants and paths. After a couple of days the moss will start to turn black and this should be raked out. DO NOT PUT TREATED DEAD MOSS RAKINGS IN THE COMPOST BIN.
After treatment DO NOT ALLOW PETS ON THE TREATED AREA FOR ONE WEEK. When treating paddocks and pastureland DO NOT ALLOW HORSES OR OTHER ANIMALS TO GRAZE ON TREATED AREA FOR 4 WEEKS.
Depending on the level of moss present, the solution can be used as an inhibitor by spraying during the period of growth from late Autumn to early Spring. This will effectively kill the upper layer of moss but if the moss is very deep, the spray will not penetrate the lower layer. By treating the upper layer of lawn with Ferrous Sulphate moss killer every four to eight weeks during the Winter months, this will help to slow down the growth of lower level moss but may not completely get rid of it.
If moss remains in the lower level of lawn, it is best to rake out the moss in early Spring. Although this can be a time consuming process, it is advisable where moss infestation is deep. Once the lower level of moss is raked out, you can treat the lawn with a solution of Ferrous Sulphate which could achieve a 90% success rate in moss eradication.
Ferrous Sulphate has a chemical formula of FeSO4 and is sometimes known as Iron Sulphate, Iron Sulfate, Ferrous Sulfate, Green Vitriol or Copperas.
Always read the Material Safety Data Sheet (MSDS) provided by your Ferrous Sulphate supplier before commencing work. Wear suitable Personal Protective Equipment (PPE) and keep out of reach of children and animals.