In the last twenty years, biological gardening has made allelopathy popular. This companion planting technique has helped fight against insects and diseases as well as accelerate the growth and improve the taste of vegetables. This way of gardening is easy to do at home and will enhance the quality of your harvests.
“Three sisters” is the name given to the oldest way of growing vegetables in this fashion. When placing squash, corn and runner beans close to each other, the vegetables benefit from one another and contribute to each other’s development. Corn stems help support runner beans. Squash foliage prevents harmful grass growth and retains the humidity in the soil. Beans, great nitrogen fixers, enrich the soil to meet the corn’s large consumption of that element; however, its foliage must be buried in the earth to decompose in order to provide this service.
The chemical interaction associated with the proximity to alliaceous plants, such as garlic, chive and onion, is well known as insect repellent. Aromatic plants can trick pests away from more appealing plants. Note that dill and tansy repel aphids and spider mites while mint and lavender keep ants away. The onion will protect surrounding plants against fungal disease such as late blight. Finally, consider planting basil to improve the growth of your tomatoes and enhance their flavour.
Some interactions can hinder rather than help. For example, the walnut tree secretes a phytotoxin called juglone that prevents germination and the growth of many plant species as well as harmful plants that would like to settle nearby.
[Main photo via Kasavox]