Companion planting guide › Three Sisters: corn, beans and squash

Three Sisters: corn, beans and squash: does it work?

Proven Consistent benefit shown in replicated field research or long-running extension trials.

Grown together, the Three Sisters produced more total food energy and protein per area than any of the single crops or mixtures of single-crop plots in New York field trials.

1. Mt.Pleasant J., Burt R.F. (2010). Estimating Productivity of Traditional Iroquoian Cropping Systems. Journal of Ethnobiology 30:52–79.
2. Mt.Pleasant J. (2016). Food Yields and Nutrient Analyses of the Three Sisters. Ethnobiology Letters (peer-reviewed).

Mechanism

Intercropping/complementary use of space: corn is the trellis, beans climb, squash covers the ground.

What the research found

• Field experiments (1993–1997, New York): corn yields were little reduced by bean and squash; beans and squash yielded much less than in their own monocultures (Mt.Pleasant & Burt 2010).
• Land Equivalency Ratios showed the polyculture more productive than monocultures of the individual crops (Mt.Pleasant & Burt 2010).
• Three Sisters yielded 12.25 million kcal/ha and 349 kg protein/ha, more than any monoculture or monoculture mixture tested (Mt.Pleasant 2016).

Caveats

The advantage is total food per area. Bean and squash harvests individually are much smaller than if grown alone. Results are from New York soils with a traditional flour corn.