What Is Co-Planting?The term co-planting ("companion planting") refers to growing different plants together with mutual benefits to both. Garlic is an especially friendly plant and can assist other crops in a variety of ways. Not only does growing garlic result in your own crop for the kitchen, it can assist the rest of your garden.
The main benefits of garlic to the home gardener are its natural fungicidal and pesticidal properties. These can help keep neighbouring plants healthy.
The powerful antibiotic and antifungal compound allicin is released when garlic cloves are crushed. This also occurs when the clove is bitten into. Thus pests attacking garlic are likely to release its natural pesticide. Some have speculated that allicin evolved this way as a defence mechanism for the crop.
Garlic co-planting is especially beneficial to lettuce (where it deters aphids) and cabbage (deterring many common pests).
As well as protecting other plants garlic can also improve their flavour. Beets and cabbage are reported to be especially good companions that benefit from this.
If you're interested in the subject of companion planting (coplanting) in general then I recommend Roses Love Garlic by Louise Riotte.
Friends and EnemiesNot all companion planting combinations are beneficial. Garlic doesn't seem to cooperate well with legumes (beans and pulses), peas or potatoes. Try not to plant these too near your garlic.
As well as co-planting the cloves themselves, you can use garlic extracts to protect other crops. There is a long tradition of treating plants with garlic solution. Recently, scientists at Newcastle University confirmed scientifically that garlic oil is efective at repelling and even killing snails and slugs.
These properties make garlic an excellent choice for the gardener who wants to avoid artificial chemicals and prefers to grow crops as near organically as possible.