Because potatoes are a root vegetable that grows below the surface of the soil, phosphate and potassium are more beneficial to potato growth. Choose an all purpose granular fertilizer with the appropriate levels of potassium and phosphate, usually 5-10-10 or 8-24-24.

What is the best fertilizer for potatoes?

The best fertilizer for growing potatoes is one which has relatively low Nitrogen (N) and is at least twice as high in Phosphorous (P) and Potash (K). A good example of a suitable potato fertilizer ratio would be a 5-10-10.

When should you feed potatoes?

Every two weeks, starting from the first week in May to the first week in September, feed your potato plants with tomato feed according to the pack instructions. If you use general purpose feed it will encourage too much foliage growth; tomato feed however will encourage potato tuber growth.