Companion Planting Guide: What to Plant Together

Companion planting is the gardener’s art of growing certain plants near each other so they help one another thrive. Some pairings deter pests, some draw in pollinators and beneficial insects, and others share shade, structure, or root space. This guide separates the well-supported ideas from the traditional folklore and gives you practical pairings for the most popular crops, plus a quick reference chart you can use at planting time.

What companion planting actually is

At its simplest, companion planting means choosing plant neighbors that support each other rather than compete. The idea is centuries old and shows up in traditions around the world, from Indigenous American polycultures to European cottage gardens. It is a core technique in any urban gardening guide because small spaces benefit enormously when every plant pulls double duty.

It is worth being honest up front: some companion planting claims are backed by solid research, while others are traditional lore passed down without rigorous testing. The most reliable benefits come from broad principles like attracting pollinators, providing physical support, and increasing diversity. Very specific claims, such as one herb dramatically improving the flavor of a neighboring vegetable, are often anecdotal. Treat this guide as a starting point for experimentation, not a set of unbreakable rules.

How companions help your garden

Pest deterrence. Strongly scented plants can mask the smell of a target crop or confuse pests that hunt by scent. Aromatic herbs like basil, rosemary, and dill are often planted among vegetables for this reason. Some plants also act as “trap crops,” luring pests away from the crop you care about, nasturtium is a classic example for aphids.

Pollinators and beneficial insects. Flowers and flowering herbs draw bees, hoverflies, lacewings, and parasitic wasps. Bees improve fruit set on crops like tomatoes, squash, and cucumbers, while predatory insects feed on aphids and caterpillars. This is one of the best-documented benefits, so interplanting flowers among vegetables is almost always worthwhile.

Shade, support, and ground cover. Tall plants can shade heat-sensitive neighbors, climbing plants can use sturdy ones as a trellis, and sprawling plants can shade the soil to suppress weeds and retain moisture. The Three Sisters method (below) is the textbook case of plants providing physical structure for one another.

Soil and nutrients. Legumes such as beans and peas host bacteria that fix nitrogen from the air, gradually enriching the soil for future crops. The effect is modest in a single season but real over time, especially when the plants are eventually turned back into the soil.

Diversity itself. Perhaps the most underrated benefit is simple variety. A mixed planting is harder for any single pest to find and devastate than a solid block of one crop. Diversity spreads risk, supports a wider range of helpful insects, and tends to keep problems smaller and slower-moving.

The Three Sisters: corn, beans, and squash

The Three Sisters is the most famous companion planting system, developed by Indigenous peoples of the Americas. Corn grows tall and provides a living pole for beans to climb. Beans fix nitrogen that helps feed the heavy-feeding corn. Squash sprawls across the ground, its broad leaves shading the soil, holding in moisture, and discouraging weeds, while its prickly stems may deter some animals. Together the three crops use space efficiently and complement each other’s needs, a genuine, time-tested example of the principle working as intended.

To try it, plant corn first and let it establish a few inches of height, then sow beans at the base and squash around the perimeter. If you are just getting started, our guide on how to start a vegetable garden walks through timing and spacing in more detail.

Good and bad pairings for popular crops

Tomatoes. Tomatoes pair well with basil, marigold, carrots, onions, and lettuce. Basil is the famous neighbor, said by many gardeners to help with flavor and pests, though the flavor claim is anecdotal. Keep tomatoes away from brassicas (cabbage family) and from potatoes, since they compete and share diseases like blight. For everything tomato-specific, see our guide on how to grow tomatoes.

Peppers. Peppers enjoy company similar to tomatoes: basil, onions, carrots, and herbs. Avoid planting them right next to brassicas, which can crowd and compete with them. Some gardeners also keep peppers away from fennel, which is widely considered a poor neighbor for many vegetables.

Carrots. Carrots do well alongside onions and leeks, whose strong scent is traditionally believed to confuse the carrot fly, and with tomatoes and lettuce. The classic warning is to keep carrots away from dill and fennel once mature, as they belong to the same family and can cross-attract pests or compete.

Beans. Beans grow happily with corn, squash, cucumbers, carrots, and lettuce. Their nitrogen-fixing makes them generous neighbors. The long-standing advice is to keep beans away from the onion family (onions, garlic, leeks), which is traditionally thought to inhibit their growth, treat this as folklore worth testing rather than proven fact.

Cucumbers. Cucumbers pair well with beans, corn, peas, radishes, and nasturtium. Nasturtium can act as a trap crop for aphids and cucumber beetles. Avoid planting cucumbers near aromatic herbs like sage, which some gardeners find stunts them, and give them room since they sprawl.

Brassicas (cabbage, broccoli, kale). Brassicas benefit from aromatic herbs (dill, mint, rosemary), onions, and from flowers like nasturtium that lure cabbage pests away. Keep them apart from tomatoes, peppers, and strawberries. Diversity is especially valuable here, since cabbage-family pests can find and strip a solid block quickly.

Lettuce. Lettuce is easygoing and fits between many crops. It does well with carrots, radishes, onions, and under taller plants that give it some afternoon shade in hot weather. There are few hard incompatibilities; just avoid crowding it so it gets light and air.

Onions and the allium family. Onions, garlic, and leeks are good neighbors to carrots, tomatoes, lettuce, and brassicas, and their scent is widely used as a pest deterrent. The traditional caution is to keep them away from beans and peas.

Herbs and flowers that earn their place

Basil is the go-to partner for tomatoes and peppers. Its strong aroma may help deter some flying pests, and when allowed to flower it attracts pollinators. Even if the flavor-boosting claim is unproven, it is a productive, low-fuss neighbor.

Marigold is the classic companion flower. French marigolds in particular are supported by research for suppressing certain root-knot nematodes in the soil, and their blooms attract pollinators and predatory insects. They are cheerful, tough, and easy, plant them throughout the beds. See how to grow marigolds for varieties and care.

Nasturtium works mainly as a trap crop, drawing aphids and cabbage pests onto itself and away from your vegetables. It also attracts pollinators, spreads as living mulch, and the leaves and flowers are edible with a peppery bite.

Dill attracts beneficial insects like hoverflies, lacewings, and parasitic wasps that prey on aphids and caterpillars. It pairs well with brassicas but should be kept away from mature carrots. Let some flower to maximize the insect benefit. Other useful flowers and herbs include calendula, borage (a bee magnet), cilantro, and yarrow.

Quick reference companion chart

How to use companion planting in practice

Start small and observe. Pick two or three pairings from the chart, try them this season, and keep simple notes on what happens. Lean on the well-supported moves first: scatter flowers and flowering herbs to pull in pollinators and predators, use legumes to build soil over time, and mix your crops instead of planting large solid blocks. These broad strategies pay off reliably.

Treat the more specific folklore, such as exact “good and bad neighbor” lists, as hypotheses rather than guarantees. Conditions vary by climate, soil, and pest pressure, so a pairing that helps one gardener may do little for another. The real engine behind companion planting is diversity and good habitat for beneficial insects, and you can lean on that even when individual claims do not pan out.

Frequently asked questions