Introduction and Companion planting basics. In Susan McClure and Sally Roth. Susan McClure is a noted proponent of organic gardening. Here she writes for home gardeners on the value and safety of using companion planting as the primary method of garden pest control. She defines companion planting as the technique of combining two or more plants in a growing area to achieve a particular purpose.
Companion planting is a centuries-old technique whose methods today are largely based on folklore.
But as McClure states, scientists, botanists, and gardeners alike are experimenting and testing to separate fact from fiction. When dealing with insects it is necessary to control harmful pests while attracting and maintaining the helpful insect population. Companion planting fulfills both requirements. For example, the pungent smells of garlic and onion are powerful deterrents to many garden pests, and mint has been shown to keep loopers off cabbage leaves. McClure also says that basil and tomato don't just taste good together but basil wards off an insect that carries a tomato leaf fungus.