Tradition
No chart mentions this pair.
Garlic
Allium sativum
Amaryllidaceae
Onion
Allium cepa
AmaryllidaceaeCan you plant garlic and onions together?
Yes, with care. Garlic and onions are close relatives: both are in the Amaryllidaceae family, so they share pests and diseases. Nothing we found says they help or harm each other beyond that.
What to watch for
Same family, shared pests. Garlic and onions are both in the Amaryllidaceae family, so the same pests and diseases can move from one to the other.
Crop Rotation in the Vegetable Garden (Steil · 2025 · Iowa State University Extension and Outreach, Yard and Garden)
What to plant with garlic and onions
Good neighbours of both, best tested first.
BeetWith garlic: Recommended by garden charts, not testedWith onions: 64% more harvest
CucumberWith garlic: Bigger combined harvestWith onions: Helpful plant chemistry
TomatoWith garlic: Recommended by garden charts, not testedWith onions: Better soil and nutrient uptake
LettuceRecommended by garden charts for both, not tested yet
What to keep away from garlic and onions
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
Same family, shared pests and diseases. Both in Amaryllidaceae: often susceptible to the same diseases and insects. Source: Iowa State University Extension and Outreach, Yard and Garden
Research
No papers found on this pair.
Yield trial
No intercropping yield trial.
Same family, careful
What happens above and below ground
Each animation illustrates a mechanism a study reported for this pair. Pick a card to focus on it.
Everything at once.
Companion plants for both garlic and onions
Plants that are good neighbours of each. Biggest harvest gain first; each cell links to the evidence for that pair.
| Plant | With garlic | With onions |
|---|---|---|
| Beet | No trial foundNot tested. Charts: recommend.Evidence for garlic and beets | 64% more harvest from the same spaceField trial, 1 study. Charts: recommend.Evidence for onions and beets |
| Cucumber | Bigger combined harvest and better soil and nutrient uptakeChemicals that hold growth backField trial, 5 studies. Charts: recommend.Evidence for garlic and cucumbers | Helpful plant chemistry and bigger combined harvestField trial, 3 studies. Charts: recommend.Evidence for onions and cucumbers |
| Tomato | No trial foundNot tested. Charts: recommend.Evidence for garlic and tomatoes | 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 |
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).
Recommended by garden charts for both, not tested yet
The evidence, with sources
- Both in Amaryllidaceae: often susceptible to the same diseases and insectsCrop Rotation in the Vegetable Garden (Steil · 2025 · Iowa State University Extension and Outreach, Yard and Garden)
All neighbours of garlic and of onion, or every pair at once in the companion planting chart.
Have you grown garlic and onions 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.