When applied regularly, it protects plants without chemical concoctions ... The active ingredients in insecticidal soap are potassium salts of fatty acids (also known as soap salts), which ...

and potassium.’ Petar Ivanov, Fantastic Gardeners' gardening expert, adds, ‘Soap and detergent can also act as wetting agents ...

Here's our guide to feeding your garden. Most plants need three major nutrients to thrive; nitrogen, phosphorous and potassium, which are generally known as NPK (their chemical symbols).