Companion Planting Chart for the Vegetable Garden (24 Crops, With Timing by Zone)

Companion planting reliably does five things, and all five are ordinary, observable horticulture rather than folklore. A tall crop like corn or trellised tomatoes casts shade a shorter, shade-tolerant crop like lettuce can use instead of wasting. A sturdy stalk like corn gives a climbing crop like pole beans something to grow on, which saves the cost and the footprint of a trellis. A legume like beans or peas pulls nitrogen from the air and leaves some of it in the soil for a heavy feeder planted nearby. A fast, sacrificial crop like radishes can pull flea beetles or cucumber beetles off a slower neighbor before it establishes. And flowering herbs like cilantro, parsley or dill, along with true flowers, draw in the hoverflies and parasitic wasps that keep aphids and cabbage worms in check later in the season.

What companion planting does not reliably do is repel specific pests by scent, improve the flavor of a neighboring crop, or protect one plant from a specific disease just by proximity, unless the mechanism is one of the handful above. Most of the “tomatoes hate potatoes,” “basil improves tomato flavor,” or “never plant X near Y” rules that circulate online trace back to a mix of old almanacs, biodynamic gardening traditions from the early twentieth century, and simple repetition, not controlled trials. Some of that folklore turns out to be true for a real, separate reason, like the tomato and potato pairing, which is actually about shared disease rather than any mutual dislike. This guide says plainly which pairings below have a mechanism behind them and which ones are tradition worth trying but not worth building a garden plan around.

The vegetable companion planting chart: 24 crops

This is a full vegetable companion planting chart for every crop covered on this site. “Why” gives the one mechanism behind each pairing, whether that is a shared pest, a nutrient interaction, a physical relationship like shade or trellising, or simply a widely held tradition, which is labeled as such rather than presented as proven.

The five pairings that actually work

Corn, beans and squash, the three sisters. This is the pairing with the most mechanism behind it, and it comes from Indigenous agricultural traditions in the Americas that predate the European term “companion planting” by centuries. Corn provides a living trellis for pole beans, which saves you building one. The beans, like all legumes, host rhizobia bacteria in root nodules that convert atmospheric nitrogen into a form the heavy-feeding corn and squash can use. The squash’s broad leaves spread across the ground between the corn stalks, shading out weeds and slowing moisture loss, which functions as a living mulch. None of that is folklore. All three effects are standard, well-understood plant physiology.

Tomatoes and basil. The popular version of this pairing claims basil repels tomato hornworms and improves tomato flavor by proximity. Neither claim has real research behind it, and it is worth saying so plainly. What does hold up is more mundane and just as useful: tomatoes and basil want the same soil warmth, the same amount of sun, and roughly the same watering schedule, and they transplant into the garden on the same timing. Planting them together is efficient bed use with two crops that will not fight each other for resources, which is reason enough even without the mythology.

Carrots and onions. This is one of the few “scent masking” pairings with genuine support from extension research. Carrot rust fly and onion fly both find their host plants largely by smell, flying low and homing in on the specific compounds each crop releases. Interplanting the two crops muddies that signal for both pests, and the effect has shown up in field trials comparing mixed and monoculture rows. It works best in a genuinely interplanted bed, alternating short rows or blocks, not a single onion at the end of a long carrot row.

Lettuce grown under a taller crop. Lettuce bolts and turns bitter in full, hot sun, which is exactly the condition a young tomato or corn planting does not yet provide but will by midsummer. Sow lettuce early, in the same bed as tomatoes, corn or trellised beans, and you get a full harvest out of it in the weeks before the taller crop fills in and shades it out. The lettuce is not fighting for the same light the tomato needs later, because by the time the tomato needs full sun, the lettuce is already finished and out of the ground.

Radishes as a trap and marker crop. Radishes germinate in five to seven days, faster than almost anything else in the garden, which makes them useful for two unrelated reasons. Sown in the same row as a slow-germinating crop like carrots, they mark the row visibly before the carrots show themselves, which is the difference between weeding accurately and hoeing out your own carrot seedlings by accident. Sown near cucumbers, squash or brassicas, radishes are fast and tender enough that flea beetles and cucumber beetles often find them first, functioning as a sacrificial trap crop that buys the slower main crop time to establish.

Pairings to avoid and why

Nightshades sharing blight. Tomatoes, potatoes and eggplant are all nightshades, and all three are susceptible to the same early blight and late blight fungi, plus verticillium wilt in the soil. Planting them side by side this season does not itself spread disease faster than planting them ten feet apart, but if one comes down with blight, the others in the same bed are the most exposed. The bigger issue is rotation: do not plant any of the three in soil where another nightshade grew in the last two to three years, since the fungal spores and verticillium persist in soil.

Legumes next to alliums. Onions and garlic release sulfur compounds from their roots that measurably suppress rhizobia, the bacteria beans and peas depend on to fix nitrogen. This is one of companion planting’s better documented negative interactions, not folklore. Keep beans and peas in a separate bed or at least a few feet from an onion or garlic row, and save the alliums for pairing with carrots, beets and brassicas instead, where they earn their keep.

Sunflowers crowding potatoes or beans. Sunflower roots release allelopathic compounds, chemicals that suppress the growth of certain neighboring plants, and potatoes and beans are two of the crops most affected. Sunflowers are worth growing as a trellis for cucumbers or a windbreak for corn, but keep them out of the potato and bean beds specifically.

Corn and tomatoes sharing a pest. Corn earworm and tomato fruitworm are the same insect, Helicoverpa zea, using two different host plants. Growing corn and tomatoes in the same bed does not cause the pest, but it does concentrate it, giving one generation of moths two crops to lay eggs on in the same square feet. Separating them by even a modest distance spreads the risk instead of stacking it.

Cucurbits crowded together. Cucumbers, zucchini, winter squash and pumpkins are all cucurbits that grow fast, spread wide and pull hard on water and nutrients. Planting several of them touching does not cause a specific disease, but the dense, humid canopy that results is exactly the condition powdery mildew and squash bugs prefer, and the plants will out-compete each other for root space regardless. Give each one the spacing its own crop page recommends rather than treating “squash family” as one bed.

Timing: companions only work if they are in the ground together

Every pairing above depends on something the folklore version of companion planting never mentions: the two crops actually overlapping in the garden at the same time. A companion planting chart that only tells you what to plant together and skips when is only half a plan, because the three sisters, tomatoes and basil, and lettuce under a taller crop all depend on specific timing relative to your last frost date, and that timing moves by weeks across zones.

For the three sisters, corn and beans are both direct sown about one week after your last frost, once the soil has warmed enough for both to germinate reliably. Squash transplants go in about two weeks after last frost, timed so the squash is a few weeks behind the corn and beans rather than competing with them from day one. Here is that timing for every USDA zone.

Tomatoes and basil share the same transplant rule, about two weeks after last frost, which is exactly why they pair so cleanly in a shared bed. A zone 6b gardener transplants both tomatoes and basil around April 29, a zone 8a gardener around April 8, and neither crop sits waiting on the other. Lettuce under tomatoes runs on the opposite clock: lettuce goes in about four weeks before last frost, which is March 18 in zone 6b or February 25 in zone 8a, well ahead of the tomato transplant date. By the time the tomato is filling out and starting to shade the bed, the lettuce planted six to eight weeks earlier has already been cut, and the ground it used is free for the tomato’s roots to spread into. That sequence, not any scent or chemistry, is the actual reason the pairing works.

Spacing and layout in a raised bed

A standard 4 by 8 foot raised bed handles a three sisters planting and a tomato and basil guild in the same season if you lay it out with the mature size of each crop in mind rather than the seed packet spacing alone. Put the three sisters at one end: corn in a block of at least four rows rather than one long row, since corn is wind-pollinated and pollinates poorly in a thin line, spaced roughly 12 inches apart in each direction. Beans go in around the base of the corn once it is 4 to 6 inches tall, two or three seeds per stalk. Squash goes along the outer edge of the block, where its vines can run off the side of the bed onto open ground or a path rather than smothering the corn and beans.

At the other end, a tomato and basil guild works well with tomatoes on 24 to 36 inch centers depending on the variety, basil tucked in the gaps between them, and a row of carrots or onions along the front edge where they get full sun and do not compete with the tomato’s root zone for long. Raised beds make this kind of guild planting easier than an in-ground row garden, because the contained soil warms faster in spring and the defined edges make it simple to keep a sprawling squash from swallowing a neighboring bed.

Where to go next

• When to start seeds indoors by zone for the indoor timing behind the tomatoes, basil and peppers in this chart.
• Last frost date: what to plant before it for the frost-tolerant crops you can get in the ground ahead of the three sisters.
• Fall planting calendar by zone for how these same pairings shift once you are sowing for autumn instead of spring.
• Best raised garden beds for beginners if you are setting up the bed this chart is meant to fill.