Gardening is more than just placing seeds in the ground and hoping they thrive. For centuries, gardeners and farmers have discovered that certain plants grow better when placed near each other, while others suffer when grown too close together. This practice, known as companion planting, is one of the oldest, most sustainable gardening techniques available—and it still works today.
In this guide, we’ll explore what companion planting is, why it works, and how you can use it to improve soil health, repel pests naturally, and increase your harvest without relying on chemicals.
What Is Companion Planting?
Companion planting is the strategic placement of different crops near each other to create mutually beneficial relationships. Some plants naturally support the growth of their neighbors by improving soil nutrients, attracting beneficial insects, or repelling pests. Others act as natural trellises or shade providers.
This practice has been used for thousands of years. Indigenous peoples in North America famously practiced the “Three Sisters” method, planting corn, beans, and squash together:
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Corn provided vertical support for the beans.
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Beans fixed nitrogen into the soil, improving fertility.
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Squash spread across the ground, suppressing weeds and retaining soil moisture.
Companion planting isn’t magic—it’s science combined with observation and tradition.
Benefits of Companion Planting
1. Natural Pest Control
Some plants release strong scents that deter unwanted insects. For example, planting basil near tomatoes helps repel tomato hornworms, while marigolds can deter nematodes and aphids.
2. Improved Soil Health
Plants like legumes add nitrogen to the soil, which benefits leafy crops such as lettuce, spinach, and kale. Deep-rooted plants like carrots or daikon radishes help break up compacted soil, improving drainage for shallow-rooted crops.
3. Pollination Support
Flowering plants attract bees, butterflies, and other pollinators, increasing fruit set for crops like cucumbers, squash, and melons.
4. Maximized Space
Companion planting allows vertical and horizontal growing strategies to work together. For instance, climbing beans can use corn stalks as natural supports, freeing up space in small gardens.
5. Weed Suppression
Ground-cover plants like clover or low-growing herbs reduce open soil exposure, minimizing weed growth.
6. Biodiversity and Garden Balance
Mixing plants creates a more diverse ecosystem, which supports beneficial insects, soil microbes, and overall plant resilience.
Key Companion Planting Strategies
1. Repel Pests with Strong Scents
Many herbs, such as rosemary, thyme, sage, and chives, produce aromatic oils that naturally deter pests. Planting them near susceptible crops helps reduce infestations.
Examples:
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Onions and garlic repel carrot flies when planted near carrots.
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Basil and oregano help repel mosquitoes and tomato hornworms near tomato plants.
2. Attract Beneficial Insects
Certain plants draw in ladybugs, lacewings, hoverflies, and parasitic wasps that feed on pests.
Examples:
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Dill and fennel attract predatory wasps that attack caterpillars.
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Alyssum attracts hoverflies that consume aphids.
3. Fix Nitrogen in the Soil
Legumes (peas, beans, clover) convert atmospheric nitrogen into a form plants can use, naturally fertilizing neighboring crops.
Examples:
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Plant peas next to spinach or lettuce for an early boost in nitrogen.
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Grow bush beans near corn to replenish soil fertility.
4. Provide Shade or Support
Tall crops like corn or sunflowers can provide shade for heat-sensitive plants or serve as trellises for climbing vines.
Examples:
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Corn supporting pole beans.
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Sunflowers shading lettuce in hot weather.
5. Use Trap Cropping
Trap crops lure pests away from your main crops, sacrificing one plant to save another.
Examples:
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Nasturtiums attract aphids away from roses and vegetables.
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Radishes can attract flea beetles away from eggplants.
Popular Companion Planting Pairings
Tomatoes
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Good Companions: Basil, marigolds, onions, carrots, parsley.
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Why: Basil repels pests; marigolds deter nematodes; carrots aerate soil; onions repel aphids.
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Avoid: Corn (attracts similar pests) and potatoes (risk of disease transmission).
Carrots
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Good Companions: Onions, leeks, rosemary, lettuce, radishes.
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Why: Onions deter carrot flies; lettuce acts as a living mulch.
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Avoid: Dill and parsnips (attract similar pests).
Cucumbers
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Good Companions: Nasturtiums, radishes, dill, sunflowers.
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Why: Nasturtiums deter cucumber beetles; dill attracts predatory insects.
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Avoid: Potatoes and sage.
Beans (Pole and Bush)
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Good Companions: Corn, squash, cucumbers, radishes, marigolds.
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Why: Beans fix nitrogen and support heavy-feeding neighbors.
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Avoid: Onions and garlic (stunt bean growth).
Lettuce
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Good Companions: Carrots, radishes, strawberries, cucumbers, onions.
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Why: Lettuce benefits from pest-repelling onions and weed-suppressing strawberries.
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Avoid: Parsley (may crowd lettuce).
Cabbage Family (Brassicas)
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Good Companions: Onions, dill, chamomile, nasturtiums, thyme.
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Why: Strongly scented herbs deter cabbage moths and aphids.
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Avoid: Strawberries (compete for nutrients).
Flowers in Companion Planting
Marigolds
Known for deterring nematodes and aphids, marigolds are great for nearly any vegetable garden.
Nasturtiums
Act as trap crops for aphids and whiteflies while also attracting pollinators.
Borage
Enhances the growth of strawberries and tomatoes while attracting bees and predatory wasps.
Calendula
Repels pests while bringing in pollinators and beneficial insects.
Herbs for Companion Planting
Basil
Perfect near tomatoes, peppers, and beans. Repels mosquitoes and tomato hornworms.
Rosemary
Good near carrots, cabbage, and beans. Repels carrot flies and cabbage moths.
Mint
Repels ants, aphids, and cabbage moths. (Grow in pots to prevent spreading.)
Chives
Great for deterring aphids and improving carrot flavor when grown nearby.
Companion Planting Layout Ideas
1. Three Sisters Garden
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Corn as a support for beans.
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Beans add nitrogen to the soil.
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Squash acts as a living mulch, reducing weeds and conserving moisture.
2. Herb Borders
Plant aromatic herbs like lavender, rosemary, and thyme around vegetable beds to deter pests and attract pollinators.
3. Interplanting Rows
Alternate rows of pest-sensitive crops (like cabbage) with strong-smelling deterrents (like onions or garlic).
4. Vertical and Horizontal Mix
Use trellises for climbing beans or cucumbers and plant root vegetables like radishes or carrots below them.
Avoiding Bad Plant Combinations
Some plants compete for resources, attract similar pests, or release chemicals that stunt each other’s growth.
Examples of Bad Companions:
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Onions and Beans: Onions can slow bean growth.
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Tomatoes and Potatoes: Share similar diseases like blight.
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Fennel and Almost Everything: Fennel secretes chemicals that inhibit nearby plants.
Companion Planting for Pest-Specific Problems
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Aphids: Use nasturtiums as trap crops or plant garlic and chives nearby.
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Japanese Beetles: Plant geraniums to attract beetles away from vegetables.
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Cabbage Worms: Place dill, thyme, or nasturtiums near cabbage and broccoli.
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Carrot Rust Fly: Plant onions, chives, or rosemary near carrots.
Companion Planting in Small Spaces
For balcony or container gardens, companion planting still works:
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Mix herbs and vegetables in the same pot (e.g., basil with tomatoes).
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Use hanging baskets for flowers that attract pollinators.
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Plant quick-growing greens under taller pepper plants.
Seasonal Companion Planting Tips
Spring
Focus on early greens and root crops with companion herbs for pest control.
Summer
Combine tall crops with ground covers to shade soil and prevent water loss.
Fall
Interplant fast-growing cool-season crops with slower-maturing ones to maximize space.
Final Thoughts
Companion planting is more than just tradition—it’s an intelligent approach to gardening that works with nature rather than against it. By carefully selecting plant combinations, you can reduce pests, increase yields, and create a more biodiverse, balanced garden.
Whether you have a small raised bed, a large backyard garden, or even a few containers on a balcony, companion planting offers a natural way to boost productivity and enjoy healthier plants—all while using fewer chemicals and creating a thriving mini-ecosystem in your backyard.