Tradition
Good
avoidgood
2 chart entries: 2 recommend, 0 advise against.
All entries cite a source.
Onion
Allium cepa
Amaryllidaceae
Cucumber
Cucumis sativus
CucurbitaceaeCan you plant onions and cucumbers together?
Yes. Onions and cucumbers grow well together. Cucumbers yielded more next to onions in a field trial, and chemicals given off by onions helped cucumbers in 2 greenhouse or pot trials.
Why onions and cucumbers work together
Bigger combined harvest. In a field trial, cucumbers yielded more next to onions.
[Effects of rotation and intercropping on bacterial communities in rhizosphere soil of cucumber]. (Wu FZ · 2008 · Ying yong sheng tai xue bao = The journal of applied ecology)Helpful plant chemistry. In 2 greenhouse or pot trials, chemicals given off by onions helped cucumbers.
Garden charts recommend it. 2 garden chart entries recommend growing them together. Charts pass on gardening tradition; they are not tests.
Effect of garlic and onion extracts or their intercropping on suppressing damping-off and powdery mildew diseases and growth characteristics of cucumber (Morsy · 2009 · Egyptian Journal of Phytopathology)
What to plant with onions and cucumbers
Good neighbours of both, best tested first.
BeetWith onions: 64% more harvestWith cucumbers: Recommended by garden charts, not tested
LettuceWith onions: Recommended by garden charts, not testedWith cucumbers: 35% more harvest
TomatoWith onions: Better soil and nutrient uptakeWith cucumbers: 17% more harvest
DillWith onions: Draws in pest-eating insectsWith cucumbers: Recommended by garden charts, not tested
KohlrabiRecommended by garden charts for both, not tested yet
What to keep away from onions and cucumbers
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
Good
avoidgood
3 papers found: 3 positive, 0 negative.
allelopathy x2yield / land use
auto-classified not reviewed by a person
Yield trial
No intercropping yield trial.
Good neighbours
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 onions and cucumbers
Plants that are good neighbours of each. Biggest harvest gain first; each cell links to the evidence for that pair.
| Plant | With onions | With cucumbers |
|---|---|---|
| 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 cucumbers and beets |
| Lettuce | No trial foundNot tested. Charts: recommend.Evidence for onions and lettuce | Fewer pests35% more harvest from the same spaceField trial, 5 studies. Charts: recommend.Evidence for cucumbers and lettuce |
| 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 | Lures pests away17% more harvest from the same spaceField trial, 4 studies. Charts: recommend.Evidence for cucumbers and tomatoes |
| Dill | Draws in pest-eating insectsField trial, 1 study. Charts: recommend.Evidence for onions and dill | No trial foundNot tested. Charts: recommend.Evidence for cucumbers 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).
Recommended by garden charts for both, not tested yet
The evidence, with sources
- Goodallelopathygreenhouse / pot trialauto-classifiedOnion helps CucumberTillering onion AcPAL and AcALL genes regulate trans‐cinnamic acid and allicin accumulation to improve cucumber environmental adaptability and growthTillering onion AcPAL and AcALL genes regulate trans‐cinnamic acid and allicin accumulation to improve cucumber environmental adaptability and growth (Fu Y · 2024 · Physiologia Plantarum.)Relevance 83% · effect confidence 90%
- Goodallelopathygreenhouse / pot trialauto-classifiedOnion helps Cucumber[Effects of intercropping Chinese onion cultivars of different allelopathic potential on cucumber growth and soil micro-environment].[Effects of intercropping Chinese onion cultivars of different allelopathic potential on cucumber growth and soil micro-environment]. (Yang Y · 2011 · Ying yong sheng tai xue bao = The journal of applied ecology)Relevance 83% · effect confidence 80%
- Goodyield / land usefield trialauto-classifiedOnion helps Cucumber[Effects of rotation and intercropping on bacterial communities in rhizosphere soil of cucumber].[Effects of rotation and intercropping on bacterial communities in rhizosphere soil of cucumber]. (Wu FZ · 2008 · Ying yong sheng tai xue bao = The journal of applied ecology)Relevance 86% · effect confidence 91%
- GoodOnion helps CucumberCucumber: helped by onionsEffect of garlic and onion extracts or their intercropping on suppressing damping-off and powdery mildew diseases and growth characteristics of cucumber (Morsy · 2009 · Egyptian Journal of Phytopathology)
- GoodOnion helps CucumberOnion: helps cucumbersEffect of garlic and onion extracts or their intercropping on suppressing damping-off and powdery mildew diseases and growth characteristics of cucumber (Morsy · 2009 · Egyptian Journal of Phytopathology)
All neighbours of onion and of cucumber, or every pair at once in the companion planting chart.
Have you grown onions and cucumbers 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.