Onion

Allium cepa

Amaryllidaceae

Pepper

Capsicum annuum

Solanaceae

Can you plant onions and peppers together?

Yes. Onions and peppers grow well together. A shared bed gave about 20% more harvest than separate beds in 5 field trials.

Why onions and peppers work together

More harvest from the same bed. In 5 field trials, a bed with both crops gave about 20% more harvest than the same space split into a onion bed and a pepper bed.
Yield and economics of chilli based intercropping system (Suresha · 2007)
and 4 more sources
Garden charts recommend it. 2 garden chart entries recommend growing them together. Charts pass on gardening tradition; they are not tests.
Intercropping for field production of peppers (Kahn · 2010 · HortTechnology)
and 1 more source

What to plant with onions and peppers

Good neighbours of both, best tested first.

DillWith onions: Draws in pest-eating insectsWith peppers: Draws in pest-eating insects

How each one was tested, with the evidence

What to keep away from onions and peppers

PeaWith onions: Garden charts advise against it, not tested
AsparagusWith onions: Garden charts advise against it, not tested
KaleWith peppers: Garden charts advise against it, not tested
Brussels sproutsWith peppers: Garden charts advise against it, not tested

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

Tradition

Good

avoidgood

2 chart entries: 2 recommend, 0 advise against.

All entries cite a source.

Research

Good

avoidgood

1 paper found: 1 positive, 0 negative.

yield / land use

auto-classified not reviewed by a person

Yield trial

Good

0.48

0.73

Pepper gains more. Partial LER is each crop's share of the yield it would give alone.

5 field trials. Published LERs lean high.

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.

What is going on (2)

Pick a card to spotlight its animation in the scene.

Onion PepperGrown together, Onion and Pepper gave more food from the same ground than apart.

Researchfield trial x1

Experimental dataset of the impact assessment of vegetable intercropping on agroeconomic performances, pests and beneficials, and soil resources. (Perrin B · 2023 · Data in brief)

Onion PepperMedian land equivalent ratio 1.20 over 5 trials: growing them together gave 1.20 times the harvest of two separate plots of the same size.

Partial LERs (medians): Onion 0.42 + Pepper 0.68. Range across treatments 1.18 to 1.32. Medians are taken separately, so the parts need not add up to the median LER. LER above 1 is biased upward by publication bias.

Yield trialfield trial x5

Yield and economics of chilli based intercropping system (Suresha · 2007)

Economic Returns and Yield of Chilli as Intercropped with Varying Onion Population (Tarafder · 2003)

3 more sources

Effect of bokashi and vermicompost leachate on yield and quality of pepper (Capsicum annuum) and onion (Allium cepa) under monoculture and intercropping cultures (Álvarez-Solís · 2016)

Effect of intercropping chili (Capsicum annuum L.) with onion (Allium cepa L.) in sandy regosol (Brintha · 2012)

Evaluation of the Yield Components and Yield of Onion (Allium cepa L.)-Pepper (Capsicum annuum L.) Intercrop in the Sudan Savanna (Kabura · 2008)

Tradition saysGood

2 gardening-lore entries. Lore is a starting point, not proof.

Intercropping for field production of peppers (Kahn · 2010 · HortTechnology)

Aspects of biologically based pest management in commercial pepper production (Frantz · 1997 · Proceedings of the Florida State Horticultural Society)

Companion plants for both onions and peppers

Plants that are good neighbours of each. Biggest harvest gain first; each cell links to the evidence for that pair.

Plant	With onions	With peppers
Dill	Draws in pest-eating insectsField trial, 1 study. Charts: recommend.Evidence for onions and dill	Draws in pest-eating insectsField trial, 1 study. Charts: not listed.Evidence for peppers and dill

The evidence, with sources

ResearchGood1 entry

Goodyield / land usefield trialauto-classified

Experimental dataset of the impact assessment of vegetable intercropping on agroeconomic performances, pests and beneficials, and soil resources.
Experimental dataset of the impact assessment of vegetable intercropping on agroeconomic performances, pests and beneficials, and soil resources. (Perrin B · 2023 · Data in brief)

Relevance 91% · effect confidence 7%

Yield trialGood5 entries

GoodLER 1.32field trial

India, 2005-2006; Additive design; median LER 1.32 over 1 treatment(s) · partial LER Onion 0.38, Pepper 0.94
Yield and economics of chilli based intercropping system (Suresha · 2007)
GoodLER 1.20field trial

Bangladesh, 1999-2000; Additive design; median LER 1.20 over 8 treatment(s) · partial LER Onion 0.61, Pepper 0.59
Economic Returns and Yield of Chilli as Intercropped with Varying Onion Population (Tarafder · 2003)
GoodLER 1.51field trial

Mexico, NA; Replacement design; median LER 1.51 over 3 treatment(s) · partial LER Onion 0.72, Pepper 0.68
Effect of bokashi and vermicompost leachate on yield and quality of pepper (Capsicum annuum) and onion (Allium cepa) under monoculture and intercropping cultures (Álvarez-Solís · 2016)

Show 2 more

GoodLER 1.18field trial

Bangladesh, 2010; Additive design; median LER 1.18 over 1 treatment(s) · partial LER Onion 0.28, Pepper 0.91
Effect of intercropping chili (Capsicum annuum L.) with onion (Allium cepa L.) in sandy regosol (Brintha · 2012)
No effectLER 1.01field trial

Nigeria, 2002-2004; Additive design; median LER 1.01 over 16 treatment(s) · partial LER Onion 0.415, Pepper 0.55
Evaluation of the Yield Components and Yield of Onion (Allium cepa L.)-Pepper (Capsicum annuum L.) Intercrop in the Sudan Savanna (Kabura · 2008)

TraditionGood2 entries

GoodOnion helps Pepper
Onion: helps peppers
Intercropping for field production of peppers (Kahn · 2010 · HortTechnology)
GoodOnion helps Pepper
Peppers: helped by onions crimson clover
Intercropping for field production of peppers (Kahn · 2010 · HortTechnology)
Aspects of biologically based pest management in commercial pepper production (Frantz · 1997 · Proceedings of the Florida State Horticultural Society)

Plan a bed with onions and peppers

All neighbours of onion and of pepper, or every pair at once in the companion planting chart.

Have you grown onions and peppers 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.