Free Garden Tool
Companion Planting Guide
Find the right plant pairings for your garden. Every relationship in this guide is backed by peer-reviewed research or university extension publications — no folk wisdom, no guesswork.
Why Companion Planting Matters
Every plant in your garden interacts with its neighbors. Some interactions are beneficial — basil volatiles disrupt whitefly host-finding on tomato, legume roots feed nitrogen to heavy-feeding corn, sweet alyssum flowers recruit hover flies whose larvae consume aphids by the hundreds.
Other interactions are antagonistic — fennel root exudates suppress germination of neighboring vegetables, allium compounds inhibit the nitrogen-fixing bacteria that beans depend on, and growing tomatoes near potatoes amplifies shared disease pressure.
Understanding these relationships is the foundation of pesticide-free gardening. When you plant the right neighbors together, the garden manages its own pest pressure.
How This Guide Is Different
Most companion planting guides repeat the same unverified claims from decades-old gardening folklore. This tool is different: every relationship cites its academic source, and every claim is classified by evidence quality.
Interaction Types
Aromatic confusion, predator recruitment, and olfactory masking that reduce pest damage
Nitrogen fixation by legumes and nutrient cycling that benefits neighboring crops
Sacrificial plants that draw pests away from target crops for monitoring and management
Flowering companions that increase pollinator visitation and fruit set
Spatial separation, biofumigation, and antifungal compounds that reduce disease pressure
Chemical inhibition of neighboring plant growth through root exudates or decomposing residues
Living trellises, windbreaks, shade provision, and efficient use of garden space
Living mulch and ground cover plantings that shade soil and suppress weed germination
Explore our Biodiversity Scorer to evaluate your garden's overall ecological health. Learn more about our pesticide-free approach.
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