Tradition
Good
avoidgood
2 chart entries: 2 recommend, 0 advise against.
All entries cite a source.
Onion
Allium cepa
Amaryllidaceae
Broccoli
Brassica oleracea var. italica
BrassicaceaeCan you plant onions and broccoli together?
Charts say yes. Nobody has tested onions with broccoli, as far as we could find.
Why we can't give a firm answer
Garden charts recommend it. 2 garden chart entries recommend growing them together. Charts pass on gardening tradition; they are not tests.
Companion Plants (Alabama Cooperative Extension System)
What to plant with onions and broccoli
Good neighbours of both, best tested first.
BeetWith onions: 64% more harvestWith broccoli: Recommended by garden charts, not tested
CabbageWith onions: 8% more harvestWith broccoli: Lures pests away
TomatoWith onions: Better soil and nutrient uptakeWith broccoli: Recommended by garden charts, not tested
CauliflowerWith onions: Bigger combined harvestWith broccoli: Lures pests away
DillWith onions: Draws in pest-eating insectsWith broccoli: Recommended by garden charts, not tested
What to keep away from onions and broccoli
The evidence in detail
For readers who want to dig in: every chart entry, study and yield trial behind the answer above, with the numbers.
Tradition, research and yield trials
Research
No papers found on this pair.
Yield trial
No intercropping yield trial.
Untested folklore
Companion plants for both onions and broccoli
Plants that are good neighbours of each. Biggest harvest gain first; each cell links to the evidence for that pair.
| Plant | With onions | With broccoli |
|---|---|---|
| Beet | 64% more harvest from the same spaceField trial, 1 study. Charts: recommend.Evidence for onions and beets | No trial foundNot tested. Charts: recommend.Evidence for broccoli and beets |
| Cabbage | Fewer pests and draws in pest-eating insects8% more harvest from the same spaceField trial, 8 studies. Charts: recommend.Evidence for onions and cabbage | Lures pests awaySame family (Brassicaceae): shares pests and diseasesField trial, 3 studies. Charts: not listed.Evidence for broccoli and cabbage |
| Tomato | Better soil and nutrient uptake and bigger combined harvestMixed results on soil and nutrientsField trial, 7 studies. Charts: not listed.Evidence for onions and tomatoes | No trial foundNot tested. Charts: recommend.Evidence for broccoli and tomatoes |
| Cauliflower | Bigger combined harvestField trial, 1 study. Charts: not listed.Evidence for onions and cauliflower | Lures pests awaySame family (Brassicaceae): shares pests and diseasesField trial, 2 studies. Charts: not listed.Evidence for broccoli and cauliflower |
| Dill | Draws in pest-eating insectsField trial, 1 study. Charts: recommend.Evidence for onions and dill | No trial foundNot tested. Charts: recommend.Evidence for broccoli and dill |
Harvest from the same space compares a bed with both crops against the same area split into single-crop beds, counting the harvest of both crops (the land equivalent ratio in yield trials).
The evidence, with sources
- GoodOnion helps BroccoliBroccoli: helped by onionsCompanion Plants (Alabama Cooperative Extension System)
- GoodOnion helps BroccoliOnion: helps broccoliCompanion Plants (Alabama Cooperative Extension System)
All neighbours of onion and of broccoli, or every pair at once in the companion planting chart.
Have you grown onions and broccoli together?
Tell other gardeners what happened: spacing, pests, harvest, or ask a question. Reader notes are not checked by us and do not change the verdicts on this page.