Pole beans Companion Plants

Claim. Corn stalks provide physical support for climbing beans; in measured Three Sisters plots the polyculture produced more food energy and protein per area than the same crops grown separately.

Mechanism. Beans climb the corn stalk, replacing a trellis; the crops differ in height and rooting and share space efficiently.

Studied in. Field plots in New York State comparing the Three Sisters with monocultures. (field)

Conditions. Sow beans 2–3 weeks after corn, when corn is about 30 cm tall. Beans sown at the base of corn plants, 2–3 beans per stalk, in blocks. Corn must be established before beans climb it.

Management. Use a sturdy, tall corn cultivar; Limit beans per stalk so they do not pull corn down; Plant corn in blocks for pollination.

Applies when. Works in a home bed large enough for a corn block (at least 1.2 × 1.2 m).

Limitations. Individual crop yields were lower than monocultures; the gain is per area, not per plant. Sweet corn is weaker-stalked than the flour corns used historically.

Evidence. Tier B: One or more relevant controlled field studies or an authoritative synthesis tied to the crop, effect and arrangement. (field trial).

Sources. Mt. Pleasant 2016; University of Minnesota Extension 2023

Reviewed August 15, 2026 by Garden Planner editorial team (pending independent horticultural review). Record corn--pole-beans--physical_support v1. Request a correction.

Claim. Beans fix nitrogen, but reviews show only a small, variable share reaches neighbouring corn during the season; most benefit comes after bean residues decompose, that is, to the following crop.

Mechanism. Rhizobial nitrogen fixation; transfer to neighbours through root exudates and decomposition.

Studied in. Review of legume nitrogen-transfer studies; Three Sisters plots. (field)

Conditions. Benefit accrues mainly to the crop planted after the beans. In-season benefit is small; do not rely on it.

Management. Leave bean roots and residues in the bed.

Applies when. Plan corn fertility as if the beans were not there; treat extra nitrogen as a bonus for next season.

Limitations. Transfer during the season is typically under 10–15% of fixed nitrogen.

Evidence. Tier B: One or more relevant controlled field studies or an authoritative synthesis tied to the crop, effect and arrangement. (meta analysis).

Sources. Thilakarathna 2016; Mt. Pleasant 2016

Reviewed August 15, 2026 by Garden Planner editorial team (pending independent horticultural review). Record pole-beans--corn--nutrient_transfer v1. Request a correction.

Claim. Climbing beans and sprawling squash occupy different layers; measured as part of the three-crop system, not as a pair.

Mechanism. Vertical versus ground-level growth.

Studied in. Three Sisters plots. (field)

Conditions. Planted together Both plants must be present at the same time.

Applies when. Only as part of the corn–bean–squash arrangement; beans need a support.

Limitations. Not tested as a two-crop pair.

Evidence. Tier B: One or more relevant controlled field studies or an authoritative synthesis tied to the crop, effect and arrangement. (field trial).

Sources. Mt. Pleasant 2016

Reviewed August 15, 2026 by Garden Planner editorial team (pending independent horticultural review). Record pole-beans--winter-squash--spatial_complement v1. Request a correction.

Claim. Climbing beans and onions are traditionally listed as incompatible. No controlled evidence found.

Mechanism. Claimed by tradition; no harmful interaction demonstrated.

Conditions. Planted together Both plants must be present at the same time.

Applies when. The planner does not separate these plants on this claim; it evaluates space, light, water and timing normally.

Limitations. No mechanism identified.

Evidence. Tier D: Traditional knowledge or structured community observations without a controlled comparison. (tradition).

Sources. University of Minnesota Extension 2023

Reviewed August 15, 2026 by Garden Planner editorial team (pending independent horticultural review). Record pole-beans--onion--flavor_or_growth v1. Request a correction.

Claim. Sunflowers are said to stunt beans. Laboratory evidence only; shading is the demonstrable problem.

Mechanism. Claimed by tradition; no harmful interaction demonstrated.

Conditions. Planted together Both plants must be present at the same time.

Applies when. The planner does not separate these plants on this claim; it evaluates space, light, water and timing normally.

Limitations. Shade and competition, not chemistry.

Evidence. Tier D: Traditional knowledge or structured community observations without a controlled comparison. (tradition).

Sources. Duke 2015

Reviewed August 15, 2026 by Garden Planner editorial team (pending independent horticultural review). Record sunflower--pole-beans--allelopathy v1. Request a correction.