Companion Planting Guide Calculator
Find the best companion plants for any vegetable or herb.
Discover which plants help each other grow and which to keep apart.
Companion planting is the practice of growing different plants near each other to create mutual benefits — improving growth, repelling pests, attracting beneficial insects, fixing nitrogen, and maximizing garden space. It’s one of the oldest and most effective techniques in organic gardening.
How companion planting works:
Pest repulsion: Some plants produce chemical compounds in their leaves, roots, or oils that confuse or deter pest insects. Basil repels aphids and thrips. Marigolds repel nematodes and whiteflies. Garlic deters aphids and Japanese beetles.
Pest attraction (trap cropping): Some plants attract pests away from others. Nasturtiums lure aphids away from tomatoes and squash — then you can remove the nasturtium with all its aphids.
Beneficial insect attraction: Flowers like dill, fennel, and yarrow attract parasitic wasps and hover flies that feed on aphids and caterpillars. A garden with diverse flowers is naturally more pest-resistant.
Nitrogen fixation: Legumes (beans, peas, clover) host nitrogen-fixing bacteria in root nodules. Planting them near heavy nitrogen feeders (corn, brassicas, leafy greens) enriches the soil naturally.
Shade and support: Tall plants can shade sun-sensitive crops in hot climates. Corn provides a natural trellis for climbing beans.
The Three Sisters: One of the most famous companion planting systems — developed by Indigenous peoples of North America:
- Corn provides a trellis for beans
- Beans fix nitrogen that feeds corn and squash
- Squash spreads low leaves that retain soil moisture and shade out weeds
Allelopathy (negative companions): Some plants release chemicals that inhibit nearby plant growth. Black walnut trees release juglone, which harms tomatoes, peppers, and many other plants. Fennel is notoriously allelopathic — keep it isolated from most vegetables.
Plants to avoid near each other:
- Onions near beans or peas (growth inhibition)
- Fennel near almost everything
- Brassicas near tomatoes
- Dill near carrots (dill attracts pests that harm carrots when mature)