Companion Plants: Why vegetables and fruit need friends
April 20-21, 2024
Gardeners’ Dirt by Janis Pope
Marigolds from university extension service. (Gary Bachman)
Tomato Hornworm, same as the Tobacco Hornworm. (Aggie Horticulture at Texas A&M University)
Cherry tomatoes (Aggie Horticulture at Texas A&M University)
Ladybug. (Aggie Horticulture at Texas A&M University)
Companion planting is a technique of growing certain plants near each other for mutual benefit. Companionship is determined by how each plant grows, or what insects or pollinators they deter or attract, or what they do to the soil to help nearby plants.
One plant does not impair the other and they each grow better than if they were not planted together. For example, one plant may deter certain types of pests, while another plant may provide nutrients that benefit other plants.
Companion planting has been around for centuries and practiced in many different civilizations. Probably the most commonly known companion in the United States is something that Native Americans have done for centuries. It is called the Three Sisters method, which involves planting squash, beans and corn near each other.
Deep-rooted squash is a good fit with shallow rooted corn and the pole beans add nitrogen into the soil that helps the heavy nitrogen feeding corn. The corn in turn provides a stalk for the pole bean to climb. And the squash gives shade and cools the soil under all three as a living mulch.
Other plant friends that love hanging out with each other are tomatoes, basil and peppers. Of course tomatoes, basil and peppers are delicious together in spaghetti sauce, but how do they help each other in the garden? Basil is a very aromatic herb that repels insects including hornworms. It is also said to improve the overall yield and flavor of tomatoes. In return tomatoes repel different pests such as aphids on the basil.
Bright flowering plants like nasturtiums and marigolds can help attract beneficial insects and pollinators to nearby plants. Yarrow attracts butterflies, bees and ladybugs. Salvia will bring in bees, butterflies and hummingbirds. French marigolds are used throughout the garden to repel various pests.
The onion and garlic family (Alliums) are a good friend to the gardener. Garlic planted around young fruit trees will repel borers.
Onions help protect from mildew and black spots as well as aphids and many other pests. They also repel cabbage butterflies and help all members of the cabbage family.
Trap crops are another interesting part of this ecosystem. Typically trap crops are grown in order to attract attention away from a main crop such as planting radishes near squash. In this method the radishes are a sacrificial plant luring squash bugs away from the squash plant.
Another category of companion plants is growing in Guilds. This system is where mutually beneficial plants are grouped together for the benefit of a fruit tree or something similar. Plants like comfrey, yarrow and dandelions can help the overall production and health of the tree.
The other side of companion plants relates to antagonistic plants that don’t like growing close to each other. Some plants should not be planted near each other because of stunted growth or increased pest infestations.
For example, the chemicals that the sunflower gives off can cause harm to those crops around it. Tomatoes and potatoes proliferate the same diseases and pests and they are both heavy feeders competing for the same nutrients in the soil.
Cucumbers do not like the strong scent emitted by some herbs leading to stunted growth. The strong odors can also confuse pollinators causing them to bypass cucumber flowers leading to less fruit. Dill planted near carrots can inhibit carrot development.
Much of gardening is experimenting and hopefully this information plus some further research will suggest new ways for you to experiment in your own garden. Happy Gardening!
The Gardeners’ Dirt is written by members of the Victoria County Master Gardener Association, an educational outreach of Texas A&M AgriLife Extension – Victoria County.
REFERENCES:
Riotte, Louise. Carrots love Tomatoes & Roses love Garlic – Secrets of Companion Planting for Successful Gardening. Storey Publishing, LLC 2004. p. Various.