An Introduction to Companion Planting

Companion planting, briefly, is the act of planting different crops in your garden in close physical proximity, based on the theory that they will help each other. The main use of this method is for deterring pests and disease without resorting to synthetic or chemical treatments. The right companion plants may even attract helpful insects, discourage weeds, improve the flavor of a fruit or vegetable, or simply beautify your fruit and vegetable garden ornamentally.

It is a widely held belief amongst many gardeners and farmers that companion planting works, although no scientific data on the subject has been collected. While many scientists cannot adequately explain how or why companion planting works, many growers agree that symbiotic relationships in nature influence all kinds of factors, particularly pest control. Natural aromas of certain plants and their root systems, which utilize food and produce waste, can influence your garden environment. Companion planting is a gardener's way of creating a community or permaculture where all plants benefit one another. It is a sustainable, organic method of pest and weed control that can also add flavor to many things you’re already growing!

If your goal is to grow your garden organically, companion planting is one technique that could help to enhance and protect your fruits and vegetables.

To start, identify potential (or existing) pests in your garden and see if a companion plants exists to help remedy the situation. If so, you can plant the repellent plants of your choice near the borders of your garden, sprinkled throughout your plot, or nearby the plants most affected by the pest you hope to deter. Here are some common garden pests and with repellent plants that are often used to deter them. (Read this article for pest descriptions and more organic pest control methods.)

Garden Pest
Repellent Plants
Aphids Chives, coriander (cilantro), garlic, nasturtiums, petunias, mint, tansy, French marigolds
Cabbage moth Catnip, celery, hemp, nasturtiums, rosemary, sage, thyme
Carrotfly Coriander, rosemary, sage
Colorado potato beetle Flax, green beans, horseradish
Japanese beetles Garlic, geraniums, tansy
Nematode Asparagus, calendula, Fresh or African marigolds
Tomato Hornworm Fresh or African marigolds, borage, opal basil

Another way to use companion planting is to enhance the flavor of your plants. "Flavor enhancing" companion plants are typically herbs. Borage, for example, is a popular companion to almost every vegetable and fruit in the garden, especially strawberries. Herbs often do double duty as flavor enhancers and repellant plants (see chart above). Here are some examples of common herbs and which plants they help enhance. Choose a flavor-enhancing herb for your fruits and vegetables, plant it nearby and let it work its magic!

Herb
Enhances the flavor of...
Basil Asparagus, oregano, peppers, tomatoes
Chamomile Basil, cabbage, cucumbers, onions
Coriander (cilantro) Spinach
Chives Apples, brassica family vegetables (broccoli, cabbage, etc.), carrots, tomatoes
Dill Cabbage, corn, cucumbers, lettuce, onions
Garlic Apples, celery, cucumbers, garlic, lettuce, pears, peas
Oregano Peppers, tomatoes
Mint Brassica family vegetables such as broccoli and cabbage
Rosemary Beans, cabbage, carrots, sage

For a complete resource of companion plants, check out this thorough list from Wikipedia.org. We also enjoyed perusing Louise Riotte's book, Carrots Love Tomatoes: Secrets of Companion Planting for Successful Gardening (Storey Publishing, 1998).