Companion Planting Chart: Compatible & Incompatible
Companion planting groups crops, herbs, and flowers that help one another grow, discourage pests, or use garden space efficiently.
The chart below lists sixteen common vegetables and garden plants with their recommended neighbors, crops to keep apart, and short notes on the reasoning behind each pairing.
Use it as a planning reference for beds and rows, while remembering that spacing, sunlight, rotation, and observation in your own garden still matter most.
FAQ
- 1
What is companion planting?
Companion planting is the practice of growing compatible plants, vegetables, herbs, and flowers close together so they can help one another. University extension defines it as growing two or more compatible plants in proximity to attract beneficial insects, repel pests, and improve overall growth. Benefits come from legumes fixing nitrogen, flowering herbs feeding pest predators, tall crops shading small ones, vines covering the soil, and mixed plantings slowing the spread of specialist pests. It organizes the garden for diversity and space efficiency rather than replacing soil care, rotation, or proven pest controls.
- 2
Do tomatoes and basil grow well together?
Yes, tomato and basil are commonly planted together as a traditional garden pairing, and many extension garden plans place basil near tomatoes and peppers. Basil's scent is associated with repelling flies, mosquitoes, and some aphids, while the two share similar sun and water requirements. The claim that basil improves tomato flavor is largely traditional observation with inconsistent study support, so treat it as a convenient, compatible neighbor rather than a proven flavor treatment. Keep beans away from basil per companion tables, since the two are listed as incompatible in extension lists.
- 3
What is the Three Sisters garden?
The Three Sisters is a traditional Native American polyculture combining corn, climbing beans, and squash planted together in hills. Corn provides a vertical stalk for beans to climb; beans fix soil nitrogen through rhizobium bacteria to feed the corn and squash; and large squash leaves shade the soil, conserve moisture, suppress weeds, and discourage browsing animals. University extension cites it as a classic spatial and symbiotic companion planting, and it works in modern beds when corn is planted first so its stalks are tall enough to support bean vines.
- 4
Why should potatoes not be planted with tomatoes?
Tomatoes and potatoes belong to the same nightshade family (Solanaceae), so they share soil-borne diseases and pests such as early blight, late blight, and Colorado potato beetle pressure; planting them close together concentrates these problems in one spot. Companion tables from Virginia Tech also list tomato as incompatible with Irish potato, along with pumpkin, squash, cucumber, and sunflower. The safe practice is to separate the two crops in the bed layout and rotate nightshade family plants to a different bed each season so disease cycles do not build up in the soil.
- 5
What do marigolds do in the vegetable garden?
Marigolds (Tagetes) are planted between vegetables for two recognized benefits. University extension notes that marigold roots release thiopene compounds that repel root-knot nematodes, and their bright flowers attract pollinators and predatory insects. Extension tables list marigolds as companions for tomatoes, potatoes, squash, cucumbers, peppers, and beans. They work best when planted in or around the bed rather than in a separate display garden, but keep soil preparation, rotation, and watering in place, since marigolds are a supplement rather than a stand-alone pest control.
- 6
Is companion planting scientifically proven?
Some mechanisms are well established, others are not. Nitrogen fixation by legumes, marigold suppression of root-knot nematodes, and flowering herbs feeding beneficial predatory insects are documented in university research and extension publications. Many traditional pairings, including specific flavor improvements between plants and broad claims that one herb repels every pest, have not held up consistently in replicated trials. Treat the chart as a planning aid for diversity, spacing, and practical synergy, and use proven measures such as rotation, sanitation, correct watering, and identified pest controls for confirmed problems in your garden.
Sources
Virginia Tech Extension, SPES-620 Companion Planting (Table 1: Compatible and Incompatible Plants)“Companion planting is the art of growing two or more compatible plants in close proximity to attract beneficial insects, repel pests, and generally improve the growth... Table 1: Tomatoes — Companions: Onion Family, Nasturtium, Marigold, Asparagus, Carrot, Parsley, Cucumber; Incompatible: Irish Potato, Fennel, Cabbage Family. Carrots — Companions: English Pea, Lettuce, Onion Family, Tomato; Incompatible: Dill, Parsnip, Radish. Corn — Companions: Irish Potato, Beans, English Pea, Pumpkin, Cucumber, Squash; Incompatible: Tomato. Potato (Irish) — Companions: Beans, Corn, Cabbage Family, Marigolds, Horseradish; Incompatible: Pumpkin, Squash, Tomato, Cucumber, Sunflower. Lettuce — Companions: Carrot, Radish, Strawberry, Cucumber; Incompatible: Garlic, Onion, Leeks, Chives. Squash — Companions: Nasturtium, Corn, Marigold; Incompatible: Irish Potato. Spinach — Companions: Strawberry, Bush Bean; Incompatible: Cauliflower, Cabbages, Broccoli.”
Virginia Tech Extension, SPES-620 Companion Planting — Mechanisms of Companion Planting“Marigolds (Tagetes) release thiopene, which is a nematode repellent... Beans, peas and other legumes form nodules on their roots with rhizobium bacteria, which fix atmospheric nitrogen for use by plants... Herbs such as dill and cilantro provide pollen and nectar for ladybugs and other beneficial insects... Three Sisters: corn provides support for beans, beans provide nitrogen for corn and squash, and squash covers the soil to retain moisture and suppress weeds.”
Montana State University Extension, Sanders County — Companion Planting Guide“Bush Bean friends: Beet, Cabbage, Carrot, Cauliflower, Celery, Chard, Corn, Cucumber, Eggplant, Leek, Marigold, Parsnip, Pea, Potato, Radish, Rosemary, Strawberry, Sunflower; adversaries: Basil, Fennel, Kohlrabi, Onion Family. Pepper friends: Early Potato, Radish, Spinach, Strawberry, Turnip; adversaries: Fennel, Kohlrabi. Cucumber friends: Early Potato, Parsley, Pea, Pumpkin, Squash, Nasturtium, Radish, Sunflower, Tomato; adversaries: Bush Beans, Cabbage Family, Corn, Dill, Eggplant, Lettuce, Potato, Sage. Onion family friends: Beet, Cabbage Family, Carrot, Kohlrabi, Leek, Early Lettuce, Parsnip, Asparagus, Bean, Pea, Sage.”