Sweet corn

Zea mays

Poaceae

Watermelon

Citrullus lanatus

Cucurbitaceae

Can you plant corn and watermelon together?

It depends. The sources disagree about corn and watermelon. A shared bed gave about 72% more harvest than separate beds in one field trial, but corn crowded watermelon out of light and water in a field trial.

Why it depends

Mixed results on competition for light and water. In a field trial, results on competition for light and water were mixed.
Optimised sowing date enhances crop resilience towards size-asymmetric competition and reduces the yield difference between intercropped and sole maize (Huang · 2018)
More harvest from the same bed. In one field trial, a bed with both crops gave about 72% more harvest than the same space split into a sweet corn bed and a watermelon bed.
Optimised sowing date enhances crop resilience towards size-asymmetric competition and reduces the yield difference between intercropped and sole maize (Huang · 2018)
Competes for light and water. In a field trial, corn crowded watermelon out of light and water.
Plant growth patterns in a tripartite strip relay intercrop are shaped by asymmetric aboveground competition (Huang C · 2017 · Field Crops Research.)

What to plant with corn and watermelon

Good neighbours of both, best tested first.

RadishWith corn: 40% more harvestWith watermelon: Bigger combined harvest

How each one was tested, with the evidence

What to keep away from corn and watermelon

CeleryWith corn: 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

No chart mentions this pair.

Research

Bad

avoidgood

2 papers found: 0 positive, 1 negative, 1 mixed.

competition x2

auto-classified not reviewed by a person

Yield trial

Good

0.79

0.88

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

1 field trial. Published LERs lean high.

It's complicated

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.

Sweet corn WatermelonSweet corn and Watermelon compete for light, water and nutrients: roots tangle and the taller plant shades the other.

Researchfield trial x2

Optimised sowing date enhances crop resilience towards size-asymmetric competition and reduces the yield difference between intercropped and sole maize (Huang · 2018)

Plant growth patterns in a tripartite strip relay intercrop are shaped by asymmetric aboveground competition (Huang C · 2017 · Field Crops Research.)

Sweet corn WatermelonMedian land equivalent ratio 1.72 over 1 trial: growing them together gave 1.72 times the harvest of two separate plots of the same size.

Partial LERs (medians): Sweet corn 0.79 + Watermelon 0.88. Range across treatments 1.50 to 1.82. 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 trialgreenhouse / pot trial x1

Optimised sowing date enhances crop resilience towards size-asymmetric competition and reduces the yield difference between intercropped and sole maize (Huang · 2018)

Companion plants for both corn and watermelon

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

Plant	With corn	With watermelon
Radish	40% more harvest from the same spaceField trial, 2 studies. Charts: not listed.Evidence for corn and radishes	Bigger combined harvestField trial, 1 study. Charts: not listed.Evidence for watermelon and radishes

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

ResearchBad2 entries

Mixedcompetitionfield trialauto-classified

Optimised sowing date enhances crop resilience towards size-asymmetric competition and reduces the yield difference between intercropped and sole maize
Optimised sowing date enhances crop resilience towards size-asymmetric competition and reduces the yield difference between intercropped and sole maize (Huang · 2018)

Relevance 95% · effect confidence 42%
Badcompetitionfield trialauto-classified

Plant growth patterns in a tripartite strip relay intercrop are shaped by asymmetric aboveground competition
Plant growth patterns in a tripartite strip relay intercrop are shaped by asymmetric aboveground competition (Huang C · 2017 · Field Crops Research.)

Relevance 91% · effect confidence 61%

Yield trialGood1 entry

GoodLER 1.72greenhouse / pot trial

China, 2013-2014; Additive design; median LER 1.71 over 6 treatment(s) · partial LER Sweet corn 0.79, Watermelon 0.875
Optimised sowing date enhances crop resilience towards size-asymmetric competition and reduces the yield difference between intercropped and sole maize (Huang · 2018)

Plan a bed with corn and watermelon

All neighbours of sweet corn and of watermelon, or every pair at once in the companion planting chart.

Have you grown corn and watermelon 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.