companion planting

Companion Planting – Does it Work?

Companion planting: growing 2 plants together that will benefit each other

So what are those benefits?

  • Companions improve plant growth – Legumes benefit their neighbours by enriching the soil with nitrogen.
  • Companions help each other grow – Taller like corn plants can provide shade for sun-sensitive shorter plants like lettuce or beans
  • Companions use garden space efficiently – Vining plants cover the ground, upright plants grow vertically. Two plants in one patch.
  • Companions prevent pest problems – Aromatic plants repel some pests. Other plants lure pests away from more desirable plants.
  • Companions attract beneficial insects – Every successful garden needs plants that attract pollinators.

Here are some great books about traditional plant pairs and companions.

There is limited scientific research on the effectiveness of companion planting. Instead, it arises from observation, traditional lore, and history.

For example, the Roman naturalist, Pliny, recommended planting chick peas with cabbage to repel the white cabbage butterfly. Roman farmers planted grain between fruit trees and grapevines. Chinese gardeners centuries ago planted beans with their grain crops.

There are some combinations that really work, and others that definitely dislike each other. The following list gives some of the more popular folklore companion pairings that work, or that should be avoided, in a vegetable garden:

  • Beans like celery and cucumbers but dislike onions and fennel.
  • Beets like bush beans, lettuce, onions, kohlrabi, and most members of the cabbage family, but not pole beans and mustard.
  • Cabbage grows better next to celery, dill, onions and potatoes, but dislike being near strawberries, tomatoes, and pole beans.
  • Carrots like leaf lettuce, radish, onions and tomatoes, but plant dill at the opposite end of the garden.
  • Corn grows well with pumpkins, peas, beans, cucumbers and potatoes, but keep tomatoes away.
  • Cucumbers like corn, peas, radishes, beans and sunflowers and dislike aromatic herbs and potatoes.
  • Lettuce grows especially well with onions, strawberries carrots, radishes and cucumbers.
  • Onions do well near lettuce, beets, strawberries and tomatoes but keep them away from peas and beans.
  • Peas like carrots, cucumbers, corn, turnips and radishes, beans, potatoes and aromatic herbs. Keep the peas away from onions, garlic, leek, and shallots.
  • Radishes grow well with beets, carrots, spinach and parsnips, cucumbers and beans. Avoid planting radishes near members of the cabbage family.
  • Squash likes icicle radishes, cucumbers and corn.
  • Tomatoes love carrots, onions and parsley, but keep cabbage and cauliflower away from them.

Here’s a great link to garden site with a clear and useful chart showing you exact combinations to plant and to avoid.

If you’d prefer, West Coast Seeds has this beautiful full color chart you can purchase. (This is not an affiliate link.)

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The opposite side of companion planting is growth suppression.

Just as we have good neighbours, there are bad plant neighbours as well. Some plants really dislike each other, and shouldn’t be planted closely together.

One of the best-known plants that suppresses growth of other plants is the black walnut tree. It produces juglone, a strong toxin that not only retards growth, but also prevents seeds from germinating.

Other plants that suppress growth are eucalyptus, sunflowers, goldenrod, quack grass, and foxtail grass. These plants produce toxins in an attempt to spread, eliminating competition for nutrients, water and sun.

The long tradition of companion planting shows that there are benefits. Much of the information you can find about companion planting is based on long-standing traditions, and not supported by actual scientific proof.

Your home garden is the best place to conduct your own experiments, to see what actually works for you.

If you decide to practice companion planting, set up your plots carefully. Keep records of what you observe. Because weather, soil types, and insect populations are variables that can affect growth, your trials and experiments should be repeated over a period of years.

Don’t expect miracles, but instead use companion planting as just one part of your entire garden experience.

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