How to read the chart
- ● Research found a benefit. At least one study found the pairing helped, usually with fewer pests or more of the insects that eat them.
- ◐ Practical. The pair works for a plain reason: one grows fast and comes out early, one shades or supports the other, or they fit together in the space.
- ○ Tradition. Widely repeated and listed by extension services, but with little or no research behind it. Worth trying, not worth worrying about.
- ✕ Keep apart. Pairs that are said to hold each other back, or where one shades the other out.
The full companion planting chart
| Crop | Grow near | Keep apart |
|---|---|---|
| Tomatoes | ● Basil (fewer thrips on tomatoes in a few studies) ● Marigolds (fewer thrips on tomatoes in a few studies) ◐ Lettuce (lettuce grows early or in the tomatoes’ shade) ◐ Spinach (spinach is picked before the tomatoes fill in) | ✕ Beans (tall tomatoes shade sun-loving bush beans) |
| Peppers | ◐ Lettuce (lettuce is picked before the peppers fill in) ◐ Spinach (spinach is picked before the peppers fill in) | – |
| Eggplant | ● Cilantro (cilantro flowers bring predators of potato beetles) ● Dill (dill flowers bring predators of potato beetles) ◐ Lettuce (lettuce grows in the eggplants’ shade) ○ Thyme (thyme is said to bring beneficial insects) | ✕ Fennel (fennel is said to slow eggplant and its relatives) |
| Potatoes | – | ✕ Sunflowers (sunflowers are said to hold potatoes back) |
| Beans | ◐ Squash and zucchini (three sisters: they share the bed with the corn) ◐ Sweet corn (three sisters: pole beans climb the corn and add nitrogen) | ✕ Tomatoes (tall tomatoes shade sun-loving bush beans) ✕ Chives (onion-family plants are said to stunt beans) ✕ Onions and garlic (onion-family plants are said to stunt beans) |
| Sweet corn | ● Buckwheat (flowering buckwheat brings predators of corn earworm) ◐ Beans (three sisters: pole beans climb the corn and add nitrogen) ◐ Squash and zucchini (three sisters: squash shades the soil and keeps weeds down) | – |
| Squash and zucchini | ● Marigolds (less squash bug and cucumber beetle damage (Iowa State study)) ● Nasturtiums (fewer squash bugs (Iowa State study)) ● Sweet alyssum (more natural enemies of aphids (Florida study)) ◐ Beans (three sisters: they share the bed with the corn) ◐ Sweet corn (three sisters: squash shades the soil and keeps weeds down) | – |
| Cucumbers | ○ Chamomile (chamomile is said to bring beneficial insects) | – |
| Lettuce | ● Sweet alyssum (more hoverfly larvae, fewer aphids) ◐ Eggplant (lettuce grows in the eggplants’ shade) ◐ Peppers (lettuce is picked before the peppers fill in) ◐ Tomatoes (lettuce grows early or in the tomatoes’ shade) ○ Chives (chives are said to deter aphids and slugs) | – |
| Spinach | ◐ Peppers (spinach is picked before the peppers fill in) ◐ Tomatoes (spinach is picked before the tomatoes fill in) | – |
| Carrots | ◐ Radishes (radishes are pulled before the carrots need the room) ○ Onions and garlic (onion scent is said to hide carrots from carrot flies) | – |
| Radishes | ◐ Carrots (radishes are pulled before the carrots need the room) | – |
| Beets | ◐ Broccoli, cabbage and kale (beets fit between broccoli plants) | – |
| Onions and garlic | ● Broccoli, cabbage and kale (less cabbageworm and looper damage on broccoli (Iowa State study)) ○ Carrots (onion scent is said to hide carrots from carrot flies) | ✕ Beans (onion-family plants are said to stunt beans) |
| Broccoli, cabbage and kale | ● Mustard and arugula (a trap crop: flea beetles go to it instead) ● Nasturtiums (less cabbageworm and looper damage on broccoli (Iowa State study)) ● Onions and garlic (less cabbageworm and looper damage on broccoli (Iowa State study)) ● Sage (fewer diamondback moths on Brussels sprouts (greenhouse study)) ● Thyme (less cabbageworm and looper damage on broccoli (Iowa State study)) ◐ Beets (beets fit between broccoli plants) ○ Calendula (calendula is said to draw aphids’ predators) | – |
| Strawberries | ○ Borage (borage brings pollinators to strawberries) | – |
| Basil | ● Tomatoes (fewer thrips on tomatoes in a few studies) | – |
| Dill | ● Eggplant (dill flowers bring predators of potato beetles) | – |
| Cilantro | ● Eggplant (cilantro flowers bring predators of potato beetles) | – |
| Thyme | ● Broccoli, cabbage and kale (less cabbageworm and looper damage on broccoli (Iowa State study)) ○ Eggplant (thyme is said to bring beneficial insects) | – |
| Sage | ● Broccoli, cabbage and kale (fewer diamondback moths on Brussels sprouts (greenhouse study)) | – |
| Chives | ○ Lettuce (chives are said to deter aphids and slugs) | ✕ Beans (onion-family plants are said to stunt beans) |
| Nasturtiums | ● Broccoli, cabbage and kale (less cabbageworm and looper damage on broccoli (Iowa State study)) ● Squash and zucchini (fewer squash bugs (Iowa State study)) | – |
| Marigolds | ● Squash and zucchini (less squash bug and cucumber beetle damage (Iowa State study)) ● Tomatoes (fewer thrips on tomatoes in a few studies) | – |
| Sweet alyssum | ● Lettuce (more hoverfly larvae, fewer aphids) ● Squash and zucchini (more natural enemies of aphids (Florida study)) | – |
| Borage | ○ Strawberries (borage brings pollinators to strawberries) | – |
| Calendula | ○ Broccoli, cabbage and kale (calendula is said to draw aphids’ predators) | – |
| Chamomile | ○ Cucumbers (chamomile is said to bring beneficial insects) | – |
| Buckwheat | ● Sweet corn (flowering buckwheat brings predators of corn earworm) | – |
| Mustard and arugula | ● Broccoli, cabbage and kale (a trap crop: flea beetles go to it instead) | – |
| Sunflowers | – | ✕ Potatoes (sunflowers are said to hold potatoes back) |
| Fennel | – | ✕ Eggplant (fennel is said to slow eggplant and its relatives) |
● research found a benefit · ◐ practical: space, shade or support · ○ tradition, little research · ✕ keep apart. Studies tested particular pests and places: a pairing that helped there may do little in your garden.
What the research says
There isn’t much of it. UMass Extension notes that rigorous studies of companion planting are few compared with the books, lists and charts built on anecdote. The pairings that have been tested mostly work in one of three ways:
- Trap crops draw pests away from the crop you want to protect. Arugula, mustard and napa cabbage pull flea beetles off other cabbage-family crops, and University of Minnesota Extension notes that mixes of three or more trap crops work better than one. Nasturtiums cut squash bug numbers around squash.
- Flowers for beneficial insects. Sweet alyssum, African marigolds, buckwheat, dill and cilantro flowers feed hoverflies, wasps and other insects that eat aphids, caterpillars and beetles. Hoverfly larvae eat large numbers of aphids.
- Mixing plants together. A bed of several crops, heights and scents is harder for pests to find than a block of one crop.
Claims the research doesn’t back
- Marigolds keep flea beetles off cabbage-family crops. Little research supports it, and some contradicts it.
- Marigolds keep Colorado potato beetles off potatoes. Several studies found they don’t.
- Marigolds protect against root nematodes just by growing nearby. The effect comes only when marigolds are grown as a cover crop and dug into the soil.
- Eggplant draws potato beetles away from potatoes. It made no difference in a University of Minnesota Extension trial.
The Three Sisters
Corn, pole beans and squash is the best-known companion planting. The corn gives the beans a stalk to climb, the beans add nitrogen to the soil, and the squash spreads over the ground, shading it and keeping weeds down. University of Minnesota Extension notes the system came from Mesoamerica and has been grown for hundreds of years by Pueblo, Mandan and Iroquois farmers. Plant the corn first; sow the beans when it is about 6 inches tall, then the squash around the edge.
Planning your beds
- Start with timing. Pairs only help if they grow at the same time: check your frost dates and start seeds on time with the seed starting calculator.
- Give each plant its space. A companion planted too close competes for light, water and food.
- Keep notes. Write down what you paired and how it went. Over a few seasons, your own notes are the best chart for your garden.
Questions people ask
What grows well with tomatoes?
Basil and marigolds: in a few studies they reduced thrips on tomatoes. Lettuce and spinach also pair well, since they are harvested early or grow in the tomatoes’ shade.
What should not be planted with beans?
Tradition says to keep onions, garlic and chives away from beans. Tall tomatoes also shade bush beans, which need full sun.
Does companion planting really work?
Some of it. Trap crops and flowers that feed beneficial insects have held up in studies. Most other pairings come from tradition and haven’t been tested.
Do marigolds keep pests away?
Sometimes. Around squash they reduced squash bug and cucumber beetle damage in an Iowa State study, and with tomatoes they reduced thrips. But studies found they don’t keep Colorado potato beetles off potatoes, and there’s little support for them against flea beetles.
Sources
- University of Minnesota Extension: Companion planting in home gardens (N. Hoidal, reviewed 2026)
- University of Arizona Extension: The Art of Companion Planting (2023)
- UMass Amherst Extension: Companion Planting in the Vegetable Garden (2012)
Checked October 15, 2026.