Companion Planting Checker
Find out which plants grow best together in your garden. Select any two plants to check their compatibility, get growing tips and see a full companion matrix.
How Companion Planting Works
Companion planting is the practice of growing certain plants near each other for mutual benefit. Some plants repel pests that attack their neighbors, while others attract pollinators or fix nitrogen in the soil. The most famous example is the Three Sisters method used by Indigenous Americans — corn, beans and squash planted together where corn provides a trellis for beans, beans fix nitrogen for all three, and squash shades the soil to retain moisture and suppress weeds. This tool checks compatibility for 30 common garden plants and explains why each pairing works or does not.
Best Companion Planting Combinations
Tomato and basil is the classic companion pair — basil repels aphids and whiteflies while improving tomato flavor. Carrots and onions protect each other because carrot flies dislike onion scent and onion flies avoid carrot foliage. Marigolds are the universal companion because they repel nematodes, aphids and whiteflies from nearly any vegetable. Planting herbs like rosemary, sage and thyme near brassicas deters cabbage moths. Nasturtiums serve as trap crops, luring aphids away from your vegetables.
Plants That Should Never Be Planted Together
Fennel is the most notorious bad companion — it releases substances that inhibit growth in most nearby plants and should be planted in isolation. Tomatoes and potatoes share the same diseases (blight) and attract the same pests, so keeping them apart reduces infection risk. Beans and onion family plants (garlic, onions, shallots) are poor neighbors because alliums stunt bean growth. Dill initially helps carrots but once it flowers, it can cross-pollinate and reduce carrot seed quality. Always check compatibility before planting to avoid stunted growth, pest problems or reduced yields.
Tips for Planning Your Companion Garden
Start with your main crop and build companions around it. If tomatoes are your priority, surround them with basil, carrots and marigolds. Use the quick-reference matrix in this tool to see all companions for any plant at a glance. Rotate your companion groups each year to prevent soil depletion. Interplant flowers like marigolds and nasturtiums throughout your vegetable beds — they attract beneficial insects and add color. Keep a garden journal to track which companion combinations perform best in your specific climate and soil conditions.