Companion Planting Checker
Select a plant and instantly see which plants make great neighbors, and which to keep far away. Based on established companion planting research for vegetables, herbs, and common garden flowers.
Check plant compatibility
Select your primary plant to see its best companions and worst neighbors.
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How companion planting works
Companion planting leverages natural relationships between plants. Some combinations work because one plant repels the pests of another. Others work because one plant improves soil nutrients (like nitrogen-fixing legumes) that benefit heavy-feeding neighbors. Some plants attract beneficial insects that pollinate or prey on pests. And some combinations simply fail because they compete for the same resources or release allelopathic chemicals that inhibit each other's growth.
Tips for success
- The "Three Sisters" (corn, beans, squash) is the most famous companion trio, corn provides a trellis, beans fix nitrogen, squash shades weeds.
- Marigolds are nearly universal companions, their roots repel nematodes and their smell deters aphids and whiteflies.
- Basil planted near tomatoes is said to improve flavor and repel thrips and aphids. Keep them about 12 inches apart.
- Avoid planting fennel near most vegetables, it releases compounds that inhibit growth in many plants.
- Mint is best kept in containers, it spreads aggressively and can crowd out neighbors while still providing pest benefits.
Good use cases
Home gardeners planning a new bed layout, market gardeners maximizing space efficiency, beginners learning which plants coexist well, and anyone dealing with pest pressure who wants to use natural deterrents before reaching for pesticides.
Classic companion combinations
- Tomato + Basil: Basil repels thrips and aphids; may improve tomato flavor according to traditional lore.
- Carrot + Onion: Each repels the other's primary pest, carrot fly and onion fly.
- Corn + Beans + Squash: The Three Sisters, a native American polyculture that maximizes yield from small space.
- Kale + Nasturtium: Nasturtiums act as a trap crop, luring aphids away from brassicas.
- Cucumber + Dill: Dill attracts beneficial insects that prey on cucumber beetles.
FAQ
Is companion planting scientifically proven?
Some combinations are well-supported by research, particularly nitrogen fixation by legumes and pest-repellent properties of marigolds and alliums. Others are based primarily on traditional gardening knowledge and anecdotal reports. The evidence varies by plant pair and mechanism. Many gardeners see real results even where formal trials are limited.
How close do companion plants need to be to work?
For pest-repellent companions, 1–3 feet is generally effective, close enough that the scent or volatiles reach the target plant. For nitrogen fixation, the legume just needs to be in the same bed. For trap crops (like nasturtiums drawing aphids away from brassicas), they should be within a few feet but not intermingled.
Can I interplant companions in a raised bed?
Yes, raised beds are ideal for companion planting because you have precise control over spacing and combinations. Focus on pairing plants that have complementary heights and growth rates to prevent shading issues, and combine heavy feeders with nitrogen fixers for best results.
Why are tomatoes and fennel incompatible?
Fennel produces allelopathic compounds, chemicals that inhibit the germination and growth of nearby plants. Tomatoes are particularly sensitive to these compounds. Most vegetables should be kept several feet away from fennel, which is best grown in its own dedicated spot.
Do I need to rotate companions each year?
Yes, follow the same crop rotation principles you'd use for any vegetable garden. Even with companion planting, avoid growing the same plant family (e.g., all nightshades or all brassicas) in the same bed in consecutive years to prevent disease and pest buildup in the soil.