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What's It For? - Sulphate of Iron

Sulphate of Iron is used for lawn improvement, moss control and for creating the acidic soils needed by lime-hating plants such as rhododendrons, azaleas, heathers etc. It darkens the lawn grasses and improves their appearance. Used regularly, it gradually increases the acidity of the soil, which discourages some weeds and favours the finer grasses. It helps to protect the lawn against some common diseases and controls moss and algae growth.

As it is soluble in water, a convenient "moss killer" can be made by dissolving 1oz in 2 gallons of water and applying this from a plastic watering can with a fine rose over 4 square yards in spring and autumn. In spring, the inclusion of sulphate of ammonia (2oz) will boost the growth of the grass but this should be omitted from the autumn treatment so that the grass will harden off for the winter.

The following information has been taken from the packaging of the fertilizers that are sold in the Trading Hut. For more information about fertilizers, their uses and explanation of the labelling see the RHS web site.


Sulphate of Iron is an inorganic fertilizer consisting of 19% Iron (Fe).

It is a plant food tonic for ericaceous (lime-hating) plants such as heathers, azaleas, rhododendrons and camellias. It can be used on any soil to correct iron deficiencies.

Directions for Use

Scatter 35g/sq.m. (1oz/sq.yd.) around the plants. Lightly fork or hoe in. Repeat once or twice during the growing season.

Application Advice

Use the recommended amount. Apply evenly without touching the plants. Avoid applying on windy days. Water well after applying. Wash hands after use. Ferrous sulphate can cause stubborn stains, so avoid the product coming into contact with clothing or surfaces other than soil. Sweep up immediately if there is a spillage. To be used only where there is a need. Do not exceed the recommended application rate.


Store in a cool dry place away from children, pets and foodstuffs.