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What's It For? - Superphosphate

Phosphates are vital in helping root development and the quick establishment of young and recently moved plants. Vegetables, especially peas, potatoes, onions and root crops benefit from them and a regular dressing encourages the vigour and colour of outdoor bulbs and flowers. Phosphates also encourage the early maturing of fruit.

Superphosphate may be applied all the year round as a base dressing before sowing or planting. Sprinkle it evenly over the whole area (2oz per square yard) and work into the top 4 inches of soil with a fork or hoe. As a top dressing to established plants, sprinkle over the whole area covered by the branch spread of established bushes, trees and shrubs (2oz per square yard). Hoe or rake in and, if dry, water in for maximum benefit. Do not apply as a heap at the base of the stem and shake off any that lodges on the foliage.

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.


Superphosphate is an inorganic fertilizer with NPK Values 0-17.5-0.

It contains nutrients essential to root growth so that young and recently-moved plants will become more quickly established, and fruit may mature earlier. It can be used as a base dressing before sowing or planting or as a spring top dressing to established woody plants. Superphosphate is also used in making John Innes Seed compost to the prescribed formula.

Directions for Use

As a Base Dressing (before sowing or planting)

70g/sq.m. (2oz/sq.yd.). Sprinkle evenly over the planting area and work into the top 10cm (4 inches) of soil with a fork or hoe.

As a Top Dressing to Established Plants

70g/sq.m. (2 oz/sq.yd.). Sprinkle beneath the branches of established trees, shrubs and fruit bushes. Hoe or rake in and, if dry; water well. Do not apply in a heap around the base of plants and keep off the leaves.

Application Advice

It is recommended that you use gloves when using this product. Use only where there is a recognised need. Do not exceed the recommended application rate. Avoid using on windy days. Wash hands after use and avoid contact with skin.


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


Superphosphate (last edited 2014-02-14 12:36:59 by PaulHowarth)