Companion Planting: Growing Plants Together

Companion planting—growing certain plants together for mutual benefit—has been practiced for centuries and continues to intrigue home gardeners. While the science behind some traditional companion pairings remains debated, thoughtful plant combinations can improve garden productivity and reduce problems. Understanding companion planting principles helps you experiment with plant combinations that may benefit your garden.

What Is Companion Planting

The concept of beneficial plant combinations.

Growing plants together that may benefit each other.

Traditional practice with varying scientific support.

May involve pest deterrence, pollinator attraction, or growth enhancement.

Some combinations based on observation; others on tradition.

Part of broader polyculture approach to growing.

Opposite is monoculture—large areas of single crops.

Potential Benefits

What companion planting may offer.

Pest deterrence through strong-scented plants.

Attracting beneficial insects.

Physical benefits (shade, support).

Maximizing space through compatible growth habits.

Soil improvement from nitrogen-fixing plants.

Diversity may improve overall garden resilience.

The Three Sisters

Classic Native American companion planting.

Corn, beans, and squash grown together.

Corn provides support for climbing beans.

Beans fix nitrogen, benefiting all three.

Squash shades soil, suppressing weeds and retaining moisture.

Traditional combination with demonstrated benefits.

Requires adequate space and proper timing.

Classic Herb Companions

Traditional herb combinations.

Basil near tomatoes—traditional pairing.

Marigolds throughout garden—reputed to deter pests.

Rosemary, sage, thyme together—similar needs.

Mint contained (spreads aggressively) but near brassicas.

Dill attracts beneficial insects but may inhibit some plants.

Many traditional pairings have some supporting evidence.

Flowers in the Vegetable Garden

Mixing ornamental and edible.

Marigolds release compounds that may deter some pests.

Nasturtiums attract aphids away from vegetables (trap crop).

Sunflowers attract pollinators and beneficial insects.

Borage attracts bees and may benefit strawberries.

Zinnias, cosmos attract beneficials.

Beauty plus function.

Plants That May Not Grow Well Together

Some combinations to potentially avoid.

Onions/garlic with beans and peas—may inhibit legumes.

Fennel may inhibit many garden plants.

Black walnut produces juglone, toxic to many plants.

Some brassicas may affect other brassicas negatively.

Evidence varies—observation in your garden is best guide.

Failed pairings may have other causes.

Nitrogen Fixers

Plants that improve soil nitrogen.

Legumes (beans, peas, clover) fix atmospheric nitrogen.

Symbiotic relationship with bacteria in root nodules.

Fixed nitrogen becomes available to other plants over time.

Pea and bean roots leave nitrogen after harvest.

Cover crops like clover build soil nitrogen.

Following legumes with nitrogen-hungry plants is traditional practice.

Pest-Deterrent Plants

Plants with reputed pest-repelling properties.

Strong scents may confuse pest-seeking insects.

Aromatic herbs: Basil, rosemary, sage, thyme, oregano.

Alliums: Onions, garlic, chives.

Marigolds: Traditional pest deterrent.

Chrysanthemums: Contain pyrethrin.

Effectiveness varies—worth trying but don't rely exclusively.

Trap Cropping

Using plants to attract pests away from main crops.

Nasturtiums attract aphids.

Mustard or radish attracts flea beetles.

Blue Hubbard squash attracts squash bugs.

Concentrated pests easier to manage.

Requires sacrificing the trap crop.

Effectiveness varies by pest and situation.

Beneficial Insect Attraction

Bringing in pest predators.

Diverse plantings attract diverse insects.

Umbel flowers (dill, fennel, yarrow) attract parasitic wasps.

Small flowers attract tiny beneficial insects.

Continuous bloom provides ongoing food source.

Insectary strips in or near gardens.

Avoid broad-spectrum pesticides that kill beneficials.

Physical Companions

Plants that help each other physically.

Tall plants provide shade for heat-sensitive neighbors.

Sturdy plants support climbing neighbors.

Fast growers mark slow-sprouting neighbors.

Ground covers suppress weeds around taller plants.

Consider mature size when planning combinations.

Timing matters—plant appropriately for desired effect.

How to Experiment

Trying companion planting in your garden.

Start with well-documented combinations.

Keep records of what you plant together.

Compare with non-companion plantings if possible.

Observe for several seasons—one year isn't conclusive.

Be skeptical of extreme claims.

Enjoy the experimentation process.

Realistic Expectations

What companion planting can and cannot do.

Won't solve major pest or disease problems alone.

May contribute to overall garden health.

Some combinations well-supported; others are tradition or myth.

Individual garden conditions affect results.

Part of holistic gardening approach.

Scientific support for specific combinations varies widely.

Companion planting combines tradition, observation, and science into a thoughtful approach to garden planning. Experimenting with plant combinations adds interest to gardening while potentially improving outcomes.

This article is for educational and informational purposes only. Results of companion planting vary and are not guaranteed.