The Complete Companion Planting Guide 2026

248 plant relationships. One interactive chart. Zero guesswork.

Companion planting is the practice of growing certain crops near each other so they help one another grow. The right pairings deter pests, improve pollination, fix nitrogen in the soil, and make better use of limited garden space. The wrong pairings stunt growth, attract disease, or compete for the same nutrients.

This guide covers the science behind companion planting, a chart of 248 tested relationships, the top combinations for your vegetable garden, common antagonist pairings to avoid, and how to use a visual planner to lay out companions in your beds.

All data in this guide comes from the Plant Anywhere companion planting engine, which draws on published agricultural research and cross-references companion relationships across 216 crop profiles.

The Science Behind Companion Planting

Companion planting is not folklore. Four well-documented biological mechanisms explain why certain crops perform better when grown together.

Nitrogen Fixation

Legumes -- beans, peas, clover, and other plants in the Fabaceae family -- form a symbiosis with Rhizobium bacteria in their root nodules. These bacteria convert atmospheric nitrogen (N2) into ammonium (NH4+), a form that plants can absorb. When legume roots decompose or are pruned, the fixed nitrogen becomes available to neighboring crops within roughly a 3-foot radius.

This is why the classic "Three Sisters" grouping works: beans fix nitrogen that corn and squash need to produce large yields. It is also why planting bush beans between rows of heavy-feeding brassicas (cabbage, broccoli, kale) reduces the need for supplemental nitrogen fertilizer.

Pest Deterrence

Many aromatic herbs and flowers produce volatile compounds that repel specific insect pests. Basil emits linalool and estragole, which deter aphids, whiteflies, and mosquitoes. Marigolds (Tagetes spp.) release alpha-terthienyl from their roots, which suppresses root-knot nematodes in surrounding soil for up to a full growing season. Garlic and chives produce allicin, which repels Japanese beetles, aphids, and spider mites.

Trap cropping is a related strategy. Nasturtiums attract aphids preferentially, drawing them away from nearby vegetables. The nasturtiums absorb the pest pressure so the crops you actually want to harvest stay clean.

Pollination Support

Flowering companion plants attract bees, hoverflies, and other pollinators to the garden. Crops that require insect pollination to set fruit -- tomatoes, peppers, squash, cucumbers, strawberries -- produce measurably higher yields when grown near borage, calendula, sunflowers, or other pollinator-attracting flowers. This effect is strongest in urban and suburban gardens where pollinator populations may be limited.

Microclimate Modification

Tall crops can provide shade for heat-sensitive neighbors. Corn shades lettuce from midsummer sun. Sunflowers create a windbreak for delicate seedlings. Low-growing squash leaves shade the soil surface, retaining moisture and suppressing weed germination. These spatial relationships are what make companion planting a layout decision, not just a planting list -- and why a visual garden planner is the best tool for getting it right.

How to Use the Companion Planting Chart

The chart below shows companion (beneficial) and antagonist (harmful) relationships between common garden crops. Here is how to read it and apply it to your garden plan.

  1. Find your main crops. Start with the vegetables you know you want to grow this season. Look them up in the chart to see their companions and antagonists.
  2. Group companions in the same bed. If you are growing tomatoes, place basil, carrots, and marigolds in the same bed or adjacent beds. These companions provide pest deterrence and pollination support.
  3. Separate antagonists by at least one bed. If your chart shows that fennel is antagonistic to tomatoes, do not plant them within 4 feet of each other. Ideally, put them in different beds entirely.
  4. Layer your companions. Combine a nitrogen fixer (beans), a pest deterrent (basil), and a pollinator attractor (marigolds) around a heavy feeder (tomatoes) for maximum benefit from a single bed.
  5. Use a visual planner. Static charts tell you what goes together. A visual planner like Plant Anywhere shows you companion lines between crops on your actual garden layout in real time, including lines across multiple beds. This makes it easy to spot conflicts before you plant.

Companion Planting Chart: 248 Relationships

The full Plant Anywhere companion planting database covers 248 relationships across vegetables, herbs, and flowers. Below is a selection of the most-searched companion pairings. For the complete interactive chart, open the Plant Anywhere garden planner (free, no account required to view).

Selected companion and antagonist relationships from the Plant Anywhere database (248 total pairs)
Crop Good Companions Antagonists (Keep Apart)
Tomato Basil, carrot, garlic, marigold, parsley, celery, borage Fennel, brassicas (cabbage, broccoli), corn, potato
Pepper Basil, carrot, onion, parsley, tomato, spinach Fennel, kohlrabi, beans
Cucumber Beans, corn, dill, lettuce, peas, radish, sunflower Potato, aromatic herbs (sage, mint)
Bean (Bush & Pole) Corn, cucumber, potato, carrot, celery, strawberry Onion, garlic, chives, leek, fennel
Carrot Lettuce, onion, pea, radish, rosemary, tomato Dill, parsnip, celery
Lettuce Carrot, chive, garlic, onion, radish, strawberry Celery, parsley
Squash Beans, corn, marigold, nasturtium, radish Potato
Garlic Tomato, pepper, lettuce, strawberry, rose Beans, peas, asparagus
Basil Tomato, pepper, oregano, lettuce, asparagus Sage, rue, thyme (compete for similar growing conditions)
Corn Beans, cucumber, melon, pea, squash, sunflower Tomato, celery
Pea Carrot, corn, cucumber, radish, turnip, bean Onion, garlic, chives
Cabbage Celery, dill, onion, chamomile, nasturtium Strawberry, tomato, pole bean
Onion Carrot, lettuce, beet, cabbage, strawberry, tomato Bean, pea, asparagus
Radish Carrot, cucumber, lettuce, pea, spinach, squash Hyssop, agastache
Strawberry Bean, borage, garlic, lettuce, onion, spinach, thyme Brassicas (cabbage, broccoli), fennel

This table covers 15 of the most commonly searched crops. The full 248-pair database is available inside the Plant Anywhere planner, where companion and antagonist lines are drawn directly on your garden canvas as you place each crop.

Top 10 Companion Planting Combinations

These are the 10 most effective companion pairings based on documented yield improvement, pest reduction, or space efficiency. Each pairing is backed by data from the Plant Anywhere companion engine's 248-pair database.

1. Tomato + Basil

The most iconic companion pair. Basil repels aphids, whiteflies, and mosquitoes with its volatile oils. Several studies suggest basil interplanted with tomatoes improves tomato flavor, though the mechanism is debated. Plant basil directly between tomato plants, not in a separate row -- the closer the proximity, the stronger the pest deterrent effect.

2. Corn + Beans + Squash (Three Sisters)

The oldest documented companion planting system in the world, developed by Indigenous American peoples over thousands of years. Corn provides a living trellis for pole beans. Beans fix atmospheric nitrogen that feeds the corn and squash. Squash shades the soil with its broad leaves, retaining moisture and suppressing weeds. Plant corn first, then beans at the base of each stalk once corn is 6 inches tall, then squash seeds between the corn hills.

3. Carrot + Onion

Carrots repel onion fly. Onions repel carrot rust fly. Grown together, each crop protects the other from its primary pest. Alternate rows of carrots and onions for maximum coverage. This pairing is especially effective in regions where carrot rust fly is a persistent problem.

4. Tomato + Marigold

French marigolds (Tagetes patula) release alpha-terthienyl from their roots, which kills root-knot nematodes in the surrounding soil. This effect persists for months after the marigolds are removed. Interplant marigolds throughout your tomato beds, not just at the edges. The nematode-suppressing compounds need to reach the root zone of your tomato plants.

5. Cucumber + Nasturtium

Nasturtiums serve as a trap crop for aphids, drawing them away from cucumber vines. The aphids preferentially colonize nasturtium stems, leaving cucumbers cleaner. Nasturtium flowers are also edible, adding a second harvest from the same bed. Plant nasturtiums at the ends of cucumber rows.

6. Lettuce + Tall Crops (Corn, Tomato, Sunflower)

Lettuce bolts (goes to seed prematurely) in hot weather. Planting lettuce in the shade of taller crops extends the lettuce harvest by several weeks in warm climates. This is a microclimate modification strategy -- the tall crop creates a cooler zone for the lettuce without any chemical interaction. Position lettuce on the north or east side of tall crops so it receives morning sun but afternoon shade.

7. Cabbage + Dill

Dill attracts parasitic wasps (Trichogramma spp.) that prey on cabbage worms, one of the most destructive brassica pests. Let dill flower rather than harvesting all of it -- the umbel flowers are what attract the beneficial insects. Plant dill directly in your brassica bed for the closest proximity.

8. Strawberry + Borage

Borage attracts pollinators that improve strawberry fruit set. It also contains pyrrolizidine alkaloids that deter some pest insects. Borage self-seeds aggressively, so plant it where you are comfortable with it spreading. One or two borage plants per strawberry bed is sufficient for pollination benefits.

9. Pepper + Garlic

Garlic's allicin compounds repel aphids, spider mites, and Japanese beetles, all of which attack pepper plants. Garlic also has mild antifungal properties that may reduce soil-borne disease pressure around pepper roots. Interplant garlic cloves between pepper plants in the fall (in zones 6+) so the garlic is established by the time peppers are transplanted in spring.

10. Bean + Potato

Beans fix nitrogen that potatoes need for tuber development. Potatoes repel Mexican bean beetles. This pairing is most effective with bush beans planted between potato rows, as pole beans could shade potato foliage. Harvest potatoes first, then let the beans continue producing into fall.

Antagonist Pairings: What NOT to Plant Together

Just as some plants help each other, others actively interfere with their neighbors' growth. Here are the most important antagonist relationships to avoid in your garden layout.

Fennel + Almost Everything

Fennel (Foeniculum vulgare) is allelopathic -- it exudes compounds from its roots that inhibit the growth of most other plants, including tomatoes, beans, peppers, and brassicas. Grow fennel in its own isolated bed or in a container. The only crops that tolerate fennel well are dill and cilantro.

Onion Family + Bean Family

Alliums (onions, garlic, leeks, chives, shallots) inhibit the growth of legumes (beans, peas, lentils). The mechanism is not fully understood, but the effect is consistent and well-documented in agricultural research. Keep your allium bed and your legume bed on opposite sides of the garden.

Potato + Tomato

Both are nightshades (Solanaceae) and share the same diseases, particularly late blight (Phytophthora infestans). Planting them near each other increases the likelihood that a blight infection in one crop will spread to the other. Separate them by at least 10 feet, and ideally by a non-nightshade bed.

Brassicas + Strawberry

Brassicas (cabbage, broccoli, kale, cauliflower) are heavy nitrogen feeders that can out-compete strawberries for nutrients. They also attract pests that damage strawberry plants. Grow them in different sections of the garden and rotate their positions each year.

Companion Planting for Flowers

Flowers are not just decorative in a vegetable garden. The right flowers provide pest control, pollination, and even soil improvement. Here are the most valuable companion flowers for vegetable growers.

Best companion flowers for vegetable gardens
Flower Benefit Best Paired With
Marigold (Tagetes) Nematode suppression, whitefly deterrence Tomato, pepper, squash, eggplant
Nasturtium Trap crop for aphids, edible flowers Cucumber, squash, beans, brassicas
Sunflower Pollinator attraction, windbreak, trellis Corn, cucumber, squash, lettuce
Borage Pollinator attraction, pest deterrence Strawberry, tomato, squash
Calendula Pest deterrence (asparagus beetle, tomato hornworm), pollinator attraction Tomato, asparagus, beans
Chamomile Growth enhancement for brassicas, pollinator attraction Cabbage, broccoli, cauliflower, onion
Lavender Deer and rabbit deterrence, pollinator attraction Lettuce, brassicas (as border planting)
Zinnia Pollinator attraction, beneficial insect habitat Squash, cucumber, pepper

Interplant these flowers throughout your vegetable beds rather than confining them to borders. The pest-deterrent and pollination benefits are strongest when flowers are growing directly among the vegetables they protect.

Companion Planting by Crop Family

If you are planning companion layouts for crops not listed in the chart above, use this family-level guide. Crops in the same botanical family generally share the same companions and antagonists.

Nightshades (Solanaceae): Tomato, Pepper, Eggplant, Potato

Companions: basil, carrot, garlic, marigold, parsley. Antagonists: fennel, other nightshades (do not interplant potato and tomato). Nightshades are heavy feeders that benefit from nitrogen-fixing companions like beans planted in the previous season or in adjacent beds.

Brassicas (Brassicaceae): Cabbage, Broccoli, Kale, Cauliflower, Brussels Sprouts

Companions: celery, dill, chamomile, onion, nasturtium. Antagonists: strawberry, tomato, pole beans. Brassicas attract cabbage worms; dill and chamomile attract the parasitic wasps that prey on them.

Legumes (Fabaceae): Bean, Pea, Lentil, Clover

Companions: corn, cucumber, potato, carrot, radish. Antagonists: all alliums (onion, garlic, chives, leek). Legumes fix nitrogen and are the best companions for heavy-feeding crops.

Cucurbits (Cucurbitaceae): Cucumber, Squash, Melon, Pumpkin, Zucchini

Companions: beans, corn, marigold, nasturtium, radish, sunflower. Antagonists: potato, aromatic herbs (sage, mint). Cucurbits need pollinators for fruit set, making pollinator-attracting flowers essential companions.

Alliums (Amaryllidaceae): Onion, Garlic, Leek, Chive, Shallot

Companions: carrot, lettuce, beet, tomato, strawberry, rose. Antagonists: beans, peas, asparagus. Alliums repel many pests, making them useful border plants for almost any bed -- except legume beds.

How to Plan Companion Planting in Your Garden

Knowing which crops go together is the first step. Turning that knowledge into an actual garden layout is where most gardeners get stuck. Here is a practical workflow.

  1. List your crops. Write down every vegetable, herb, and flower you want to grow this season.
  2. Check the chart. For each crop, note its companions and antagonists. Look for crops that share common companions -- these should go in the same bed.
  3. Group by compatibility. Create 2-4 bed groupings. Example: Bed 1 = tomato, basil, carrot, marigold. Bed 2 = beans, corn, squash (Three Sisters). Bed 3 = lettuce, radish, chive, strawberry. Bed 4 = onion, beet, garlic (allium bed, away from beans).
  4. Separate antagonists. Make sure no antagonist pairs share a bed. Check that fennel is isolated. Check that alliums and legumes are in different beds.
  5. Place crops on your layout. Use a visual garden planner to drag crops into beds and see companion/antagonist lines in real time. Plant Anywhere draws green lines between companions and red lines between antagonists directly on your garden canvas, including lines across beds.
  6. Adjust spacing. Make sure companion plants are within 2-4 feet of each other. Use the planner's spacing rings to check that nothing is overcrowded.

Plan Your Companion Planting Layout with Plant Anywhere

Plant Anywhere is a free garden planner with a built-in companion planting engine covering 248 plant relationships. When you place crops on the spatial garden grid, the planner draws companion lines between compatible plants and warns you about antagonist pairings -- including relationships across multiple beds.

What makes it different from a static chart:

Start planning your companion planting layout -- free

Related Guides

Frequently Asked Questions

What is companion planting?

Companion planting is the practice of growing certain crops near each other so they benefit one another. Benefits include pest deterrence, improved pollination, nitrogen fixation, and better use of garden space.

What should I plant next to tomatoes?

Plant basil, carrots, garlic, marigolds, and parsley next to tomatoes. Basil repels aphids and whiteflies while improving tomato flavor. Marigolds deter nematodes in the soil. Avoid planting fennel, brassicas, or corn near tomatoes.

What vegetables should not be planted together?

Avoid planting fennel near most vegetables, onions near beans or peas, potatoes near tomatoes (both are nightshades and share blight), and brassicas near strawberries. These antagonist relationships can reduce yields or increase disease pressure.

Does companion planting really work?

Yes. Research confirms several companion planting mechanisms: legumes fix atmospheric nitrogen for neighboring crops, aromatic herbs repel specific insect pests, tall crops provide shade for heat-sensitive plants, and flowers attract pollinators that increase fruit set on nearby vegetables.

What is the Three Sisters planting method?

The Three Sisters is a companion planting technique from Indigenous American agriculture. Corn provides a trellis for beans, beans fix nitrogen for the corn and squash, and squash leaves shade the soil to retain moisture and suppress weeds. All three crops benefit from growing together.

How close should companion plants be?

Companion plants work best when planted within 2 to 4 feet of each other. Pest-deterrent herbs like basil should be interplanted directly among the crops they protect. Nitrogen-fixing legumes benefit neighbors within a 3-foot radius as their root nodules release nitrogen into the surrounding soil.

Can companion planting replace pesticides?

Companion planting can significantly reduce pest pressure but is best used as part of an integrated approach. Marigolds, nasturtiums, and aromatic herbs deter many common garden pests. Combined with crop rotation and good garden hygiene, companion planting can eliminate the need for chemical pesticides in most home gardens.

What flowers are good companion plants for vegetables?

Marigolds deter nematodes and whiteflies. Nasturtiums act as trap crops for aphids. Sunflowers attract pollinators and provide shade. Borage attracts bees and repels tomato hornworms. Calendula deters asparagus beetles and tomato hornworms. Interplanting flowers throughout the vegetable garden improves pollination and reduces pest damage.

Is there a free companion planting chart?

Yes. Plant Anywhere provides a free interactive companion planting chart covering 248 plant relationships. Unlike static PDF charts, the Plant Anywhere companion planting tool shows companion and antagonist lines directly on your garden layout as you place crops, so you can see which plants help or hinder each other in real time.

What herbs are good companions for most vegetables?

Basil, dill, cilantro, parsley, and chives are beneficial companions for most vegetables. Basil repels aphids and flies. Dill and cilantro attract predatory insects that eat garden pests. Parsley attracts hoverflies. Chives deter aphids and Japanese beetles. Plant these herbs throughout your vegetable beds for broad-spectrum pest protection.