Having a mixed natural growing system provides greater biodiversity, which in turn creates much more stability and resilience in the face of changing conditions. In nature, plants grow in close communities with a number of different species existing side by side – unlike the rigid rows of single crops found in many vegetable gardens – and companion planting can provide specific benefits to vegetables, fruits, herbs and ornamentals.
Many flowering plants – most members of the daisy family, for instance – will attract predatory insects such as hoverflies and ladybirds, both of which will consume aphids. The odour produced by certain plants can deter many pests, such as whiteflies and aphids. Odoriferous plants, including those with aromatic oils, can play an important part in determining which insects visit the garden. For example, hemp can be used to repel the cabbage white butterfly. Other strongly scented plants, such as sweet basil, lemon balm, thyme and mint, work by simply confusing pests, many of which are lured to their target by scent alone.
Many plants in the legume family, such as peas, beans and clovers, possess the ability to “fix” nitrogen from the atmosphere for their own and neighbours’ use. What is not used is left in the soil for the benefit of subsequent crops. The addition of clover to grass mixtures is an old farming practice. Clover can also be interplanted amongst sweetcorn, which will benefit from the clover as a ground cover. The clover can be left after the corn has been harvested to protect the soil during the winter. In the spring it can be dug into the ground, where its nutrients will be released to feed other plants.
Growing a mixture of plants together helps to create a diverse habitat capable of supporting a wide range of insects. These in turn will prey on the more common pests. Growing a range of flowering “attractant” plants will encourage ladybirds, hoverflies, lacewings and other beneficial insects. This will achieve a reduction in crop damage and allow you to eliminate pesticide use.