Iron Sulphate for a Grass Green Green-Up Ferrous Sulphate
As a ‘green-up’ for turf Ferrous Sulphate would be mixed with water at the rate of 50 to 150 grams to treat 100 square metres of lawn. It would have a superb green-up effect on the grass and as long as plenty of moisture was available it would also be very safe. This means you can use iron sulphate at these concentrations pretty much any time of year as long as good soil moisture is available and there is no strong sun or heat.
Iron Sulphate for Hardening & Disease Resistance
Increase the concentration to 150 to 200 grams and not only will it have a good green-up effect but it will also start to ‘harden’ the turf making it more resistant to disease and fungal attack. This is a very common practice on sports turf in late autumn and winter. . I suggest you only consider applying between September and April when plenty of moisture is available and there is no likelihood of strong sunshine.
Were you to do a repeat application (double dose) at the turf hardening rate or just increase the concentration to 400 to 500 grams it will green the grass and harden the turf . If you apply at this rate ensure cool wet conditions to aid penetration and reduce any possibility of temporary damage to the grass. The maximum safe limit for Ferrous Sulphate is 500 grams per 100 square metres in at least 5 and preferably 10 litres of water. This strength is perfectly safe for the grass in cool wet conditions.