Companion Planting Checker

Companion planting is the practice of growing certain plants close together because they help one another. Good companions can repel pests, attract pollinators and predatory insects, improve the soil, provide shade or support, or simply use space efficiently. It is a low-cost, chemical-free way to build a healthier, more productive garden by working with natural relationships between plants.

Some pairings have solid science behind them, such as legumes adding nitrogen for heavy feeders, tall crops shading tender greens, and strongly scented herbs masking the scent of a target crop from pests. Others come from generations of gardener observation and are more anecdotal. Treat the suggestions as helpful, time-tested guidelines rather than guarantees, and keep notes on what works in your own conditions.

Plants are flagged to keep apart for a few reasons. Some compete for the same nutrients, water, or root space, like two heavy feeders planted together. Others attract or harbor the same pests and diseases, so growing them side by side concentrates the problem. A few, such as fennel, release natural compounds that slow the growth of nearby plants, a phenomenon called allelopathy.

The Three Sisters is a classic Native American companion planting trio of corn, beans, and squash. The corn provides a tall stalk for the beans to climb, the beans fix nitrogen in the soil to feed the corn and squash, and the sprawling squash leaves shade the ground, conserve moisture, and deter pests. Grown together, the three support each other far better than any one alone.

Marigolds and nasturtiums are two of the most useful companion plants. Marigolds release compounds that repel root-knot nematodes and deter many insect pests, which is why they pair well with tomatoes, beans, squash, and more. Nasturtiums work as a trap crop, drawing aphids and squash bugs onto themselves and away from your vegetables, while also attracting beneficial predators.

Close enough to interact but not so close they crowd each other. Aphid-repelling herbs and trap crops work best within a foot or two of the plants they protect, while nitrogen-fixers benefit neighbors across a whole bed. Always respect each plant’s normal spacing so roots and leaves are not competing. Our Plant Spacing and Square Foot Garden tools can help you lay it all out.

Yes. Being poor companions only means they should not share the same bed or be planted right next to each other. You can still grow tomatoes and brassicas, or beans and onions, in the same garden as long as you give them separate beds or put a good amount of space between them. Crop rotation between seasons also helps keep antagonistic plants apart.