Companion Planting

Using Plants to Protect Other Plants

Protecting plants from unwanted insects by using other plants is the natural, chemical-free way to remove unwanted insects from your garden. And you won't be eliminating all the beneficial bugs.

Recent research has indicated that plants produce excessive foliage and can afford some pruning. Natural pruning by insects can improve yields and increase the vitamin content of fruit in certain plants.

Planting practices

A certain relationship exists between plants, and between insects and plants. Companion planting is the usual name given to the practice of planting according to these relationships, but actually four different practices are involved.

Mixed: Planting several different plants together, as in nature, so that insects are confused by the multitude of "smells" and have more difficulty finding the plant they prefer to eat and lay their eggs on.

Repellant: Certain plants such as marigolds, mints and garlic are offensive to some insects, and will deter them when planted near other plants.

Companion: Combinations of plantings produce crops that grow better and healthier because of their proximity.

Trap: Lure plants are located near a plant you want protected. Insects attack them and can then be handpicked and destroyed.

Additional tips

  1. Learn to identify insects and diseases so you'll be able to detect problems early.
  2. Encourage natural enemies such as toads, birds, ladybugs and praying mantis.
  3. Rotate crops to avoid a build-up of pests in any one area.

Helpful herbs and flowers

When planning your next garden, experiment with these forms of natural plant protection. No doubt you will also come up with your own safe and effective combinations.
Plant Companion Advantages
Basil Tomato Improves growth and flavour; repels flies and mosquitoes.
Dill Tomato Traps the tomato hornworm.
Garlic Roses, Raspberries Improves growth and health; deters Japanese beetle.
Lamb's Quarter throughout garden, near corn Traps for aphids.
Marigolds (smelly types like Mexican, African and French) throughout garden Discourages Mexican beetle, nematodes and other insects.
Mint cabbage, tomato Improves health, flavour; deters white cabbage moth.
Nastrium radish, cabbage, cucurbits and other fruit trees Trap for aphids. Deters squash bugs and striped pumpkin beetles.
Wormwood in perrenial border Deters small animals and flea beetle
* Adapted from materials produced by the Canadian Organic Growers, Toronto.