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Companion planting checker

Pick a plant. We show its neighbours and how well each tip is backed. Green and red only with a study or a clear reason.

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What do you want to plant?

What the colours mean

  • Good neighbour· A–C
  • Better not side by side· A–C
  • Disputed· X
  • Gardeners’ lore, not proven· D
A
Backed by several trials
B
Hint from one study
C
Expert rule with a reason
D
Tradition, named by at least two sources
X
Sources disagree

Neighbours with evidence

All 39 pairs with evidence
  • Tomato + PotatoBetter not side by side· CBoth get late blight; side by side, tomatoes catch it more easily.
  • Sweetcorn + Pole beanGood neighbour· CCorn works as a pole for the beans and saves space. Whether the mix yields more is unclear.
  • Sweetcorn + Bush beanGood neighbour· CBush beans cope with the corn's shade and root at a different depth – little competition.
  • Sweetcorn + Pumpkin and winter squashGood neighbour· CSquash fills the space between corn plants, shades the soil and suppresses weeds.
  • Pumpkin and winter squash + Pole beanGood neighbour· CBig squash leaves keep the soil moist and shaded, which is said to help bean flowering.
  • Carrot + TomatoGood neighbour· CCarrots dislike heat; tomatoes give them shade.
  • Butterhead lettuce, Loose-leaf lettuce, Iceberg lettuce + TomatoGood neighbour· CLettuce bolts in heat; in the shade of tall tomatoes it stays tender longer.
  • Butterhead lettuce, Loose-leaf lettuce, Iceberg lettuce + SweetcornGood neighbour· CLettuce grows fast between the corn and gets shade there; it is picked before the corn closes in.
  • Sweetcorn + RadishGood neighbour· CRadishes are harvested between the corn before it shades them out.
  • Cucumber + SweetcornGood neighbour· CSmall pickling cucumbers can climb the corn, saving space.
  • Cucumber + Bush bean, Pole beanGood neighbour· CBeans fix nitrogen, but it is only released once their roots rot in the soil.
  • White cabbage, Red cabbage, Savoy cabbage, Cauliflower, Broccoli, Brussels sprouts, Kale, Kohlrabi, Chinese cabbage, Pak choi + Pea, Sugar snap and snow pea, Bush bean, Pole bean, Runner bean, Broad bean (fava bean)Good neighbour· CLegumes fix nitrogen that cabbage can use – but it is only released once their roots rot.
  • White cabbage, Red cabbage, Savoy cabbage, Cauliflower, Brussels sprouts + Butterhead lettuce, Loose-leaf lettuceGood neighbour· CLettuce grows fast in the gaps between young cabbages and is picked before the cabbage closes the rows.
  • Brussels sprouts + RadishGood neighbour· CRadishes are harvested between the sprouts before these shade them out.
  • Pea + RadishGood neighbour· CThere is room for a row of radishes between two rows of peas.
  • Sweetcorn + SpinachGood neighbour· CEarly spinach uses the gaps while the corn is small – it must be gone by mid-June or the corn suffers.
  • Cucumber + Butterhead lettuceGood neighbour· CCucumbers only go in mid-May; until then, and along the edge, there is room for lettuce.
  • Leek + Butterhead lettuceGood neighbour· CLeeks only grow strongly in late summer; until then quick lettuce fits in the row.
  • Leek + KohlrabiGood neighbour· CLeeks grow slowly; early kohlrabi is harvested before they need the space.
  • Sunflower + Pole beanGood neighbour· CSunflowers act as a support for climbing beans.
  • Tomato + BasilGood neighbour· BIn garden trials, tomato and basil together out-yielded either crop alone – especially when planted densely.
  • Brussels sprouts + BasilGood neighbour· BIn the same garden trial, basil next to Brussels sprouts also paid off (higher combined yield).
  • Butterhead lettuce, Loose-leaf lettuce, Iceberg lettuce + Sweet alyssumGood neighbour· BSweet alyssum draws beneficial insects that eat aphids; lettuce next to it had fewer aphids.
  • Tomato + French marigold (tagetes)Good neighbour· BIn a greenhouse trial, whiteflies built up more slowly on tomatoes next to French marigolds (limonene). Other mixed partners had a similar effect.
  • White cabbage + TomatoGood neighbour· BIn two field trials in Myanmar, cabbage next to tomatoes had markedly fewer diamondback moth caterpillars. Cooler climates were not tested.
  • White cabbage + Chilli pepperGood neighbour· BIn the same Myanmar trial, cabbage next to chilli had fewer diamondback moth caterpillars.
  • White cabbage + French marigold (tagetes)Good neighbour· BIn a two-year field trial in India, cabbage next to marigolds had fewer diamondback moth caterpillars.
  • Carrot + French marigold (tagetes)Good neighbour· BIn a field trial, carrots grown with French marigolds had the least carrot fly damage; yield did not drop.
  • Carrot + Pot marigold (calendula)Good neighbour· BIn the same trial, carrots next to pot marigolds had the least nematode damage.
  • Carrot + Spring onion (scallion)Good neighbour· BCarrots grown with Welsh onions had less carrot fly damage and higher yields in a trial.
  • Coriander (cilantro) + Basil, ParsleyGood neighbour· BAccording to the RHS, coriander sometimes kept pests off basil and parsley – not reliably.
  • Onion + CarrotDisputed· XClassic pairing against carrot and onion fly. Trials show slightly less carrot fly while onions are young; the Bavarian garden academy advises against it because nutrient and water needs differ.
  • White cabbage, Red cabbage, Savoy cabbage, Cauliflower, Broccoli, Brussels sprouts, Kale, Kohlrabi, Chinese cabbage, Pak choi + GarlicDisputed· XCharts call garlic a bad neighbour for cabbage. Field trials in China and India instead found fewer cabbage white caterpillars, aphids and diamondback moths.
  • White cabbage, Red cabbage, Savoy cabbage, Cauliflower, Broccoli, Brussels sprouts, Kale, Kohlrabi, Chinese cabbage, Pak choi + OnionDisputed· XCharts call onions a bad neighbour for cabbage. A field trial in India found fewer diamondback moth caterpillars next to onions.
  • Carrot + DillDisputed· XSaid to be a good neighbour and it cut carrot fly damage in a trial – but carrot yield fell markedly.
  • Cucumber + RadishDisputed· XBUND lists radishes as bad cucumber neighbours; the Rhineland-Palatinate garden academy plants them next to cucumbers.
  • Chinese cabbage, Kale + LeekDisputed· XBUND lists leeks as good cabbage neighbours; the Rhineland-Palatinate garden academy advises against them for Chinese cabbage and kale.
  • Celery + Butterhead lettuceDisputed· XBUND lists lettuce as a good celery neighbour; the Rhineland-Palatinate garden academy advises against it for celery.
  • White cabbage, Red cabbage, Savoy cabbage, Cauliflower, Brussels sprouts + KohlrabiDisputed· XAccording to the garden academy, early kohlrabi fits the gaps between young cabbages; BUND advises against other brassicas as neighbours.

Questions and answers

Are there studies on companion planting?

For a few pairs, yes, such as basil next to tomatoes. For most pairs in garden charts, evidence is missing. The Bavarian Garden Academy writes that such effects are hard to prove. What is clear: planting too close does the most harm.

Why are some pairs grey?

Grey means gardeners’ lore. At least two sources name the pair, but no study backs it. Trying it does no harm.

Do onions and carrots go together?

That is disputed. The German conservation group BUND recommends the pair; the Bavarian Garden Academy advises against it because they need different amounts of water and nutrients.

Why not tomatoes next to potatoes?

Both get late blight. Planted close together, tomatoes catch it more easily. That is the advice of the Schleswig-Holstein Chamber of Agriculture.

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