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The Three Sisters

The ancestral Native American pairing of corn, bean, squash.

Watch the videoLa méthode Milpa (maïs, courge, haricot)Zeprofdortie : PERMACULTURE

Explanation

The corn serves as a support for the climbing bean, the bean fixes nitrogen from the air, and the squash covers the soil and limits evaporation. Their advantage comes partly from roots that explore the soil differently (Zhang et al., 2014; Postma and Lynch, 2012), and the bean's nitrogen returns to the soil mostly when its residues go back into it. From the same area, the trio yields more energy and protein than each crop grown alone (Mt.Pleasant, 2016); in the garden, the mound is still enriched with compost, as for any squash (RHS). A thousand-year-old practice passed down by the Haudenosaunee (Iroquois Confederacy), the Wendat (Hurons) and many other nations of North and Central America.

Refined definition

The Three Sisters (“Diohé:ko” in Mohawk, “We:nh” among the Hopi) refers to the three-way corn-bean-squash cropping combination on the same mound. Among the Haudenosaunee peoples, it is not only an agricultural technique: it is a spiritual teaching about cooperation and reciprocity. It is also nutritionally complete: corn provides the carbohydrates, the bean the protein (with the amino acids corn lacks, lysine, tryptophan), the squash vitamins A and C.

Key points

  • The science behind the guild

    Corn (Poaceae): fast vertical growth, wind-pollinated, nitrogen-hungry, the stalk serves as a support. Climbing bean (Fabaceae): symbiosis with Rhizobium that fixes nitrogen from the air, part of which returns to the soil with its residues; twining, it climbs the corn in a spiral. Squash (Cucurbitaceae): broad leaves that cover the soil, shade it, retain moisture, a natural weed suppressant. Studies: Mt. Pleasant J. (2006), The Science behind the Three Sisters Mound System, in Histories of Maize (Staller, Tykot and Benz eds.), Academic Press; Mt.Pleasant J. (2016), Ethnobiology Letters 7(1):87-98.

  • The traditional planting method

    A mound or “hill” about 80 cm to 1 m wide and 15 to 20 cm high (a gardener's rule of thumb), enriched with compost. 1) Sow 4-5 corn kernels at the centre, spaced 25 cm apart in a staggered pattern, wait for emergence (May-June). 2) When the corn reaches 15-20 cm, sow 4 climbing-bean seeds in a circle around the corn plants. 3) On the sides of the mound, sow 2-3 squash seeds. Mulch generously. Staggered harvest: green beans July-August, squash September-October, corn as dry grain at full maturity.

  • The Haudenosaunee teaching

    Robin Wall Kimmerer (botanist, member of the Citizen Potawatomi Nation), in Braiding Sweetgrass (2013), presents the Three Sisters not as three juxtaposed crops but as three sisters that grow together: the corn lends its stalk to the bean, the bean fixes the nitrogen the soil needs, the squash covers the earth and protects them all. The lesson she draws from it goes beyond the field, reciprocity means we do not succeed alone. (Paraphrase of the author, not a word-for-word quotation.) Source: Robin Wall Kimmerer, Braiding Sweetgrass, Milkweed Editions, 2013.

Watch out for

  • • Choose suitable varieties: a tall-stemmed corn harvested ripe for grain (flour, polenta, popcorn), since a sweetcorn, picked immature, is far less nourishing (Mt.Pleasant, 2016), CLIMBING bean (not dwarf, it will not climb the corn), TRAILING squash (not bush).
  • • Stagger the sowings: if all three are sown at once, the bean smothers the young corn.
  • • Suited to the annual vegetable-garden guild, not a miracle solution, but an excellent entry point to the permaculture guild.

Sources

  • Mt. Pleasant, J. (2006). The science behind the Three Sisters mound system: an agronomic assessment of an indigenous agricultural system in the northeast. In Staller, J.E., Tykot, R.H. & Benz, B.F. (dir.), Histories of Maize (p. 529-537). Academic Press.
  • Mt. Pleasant, J. (2016). Food yields and nutrient analyses of the Three Sisters: a Haudenosaunee cropping system. Ethnobiology Letters, 7(1).
  • Zhang, C., Postma, J.A., York, L.M. & Lynch, J.P. (2014). Root foraging elicits niche complementarity-dependent yield advantage in the ancient 'three sisters' (maize/bean/squash) polyculture. Annals of Botany, 114(8), 1719-1733.
  • Postma, J.A. & Lynch, J.P. (2012). Complementarity in root architecture for nutrient uptake in ancient maize/bean and maize/bean/squash polycultures. Annals of Botany, 110(2), 521-534.
  • Kimmerer, R.W. (2013). Braiding Sweetgrass: Indigenous Wisdom, Scientific Knowledge, and the Teachings of Plants. Minneapolis : Milkweed Editions.