Planting the three sisters

I had a conversation recently with someone talking about the benefits of companion plantings and the Three Sisters in particular. Being wired from graduate school to always questions whether something was simply theory or research-based scientific fact, I decided it was time to investigate.

The Iroquois have been credited with this agriculture technique of planting corn, beans and squash together. Iroquois legend has it that corns, bean and squash are “precious gifts from the Great Spirit, each watched over by one of the Three Sisters’ spirits”. https://extension.psu.edu/programs/master-gardener/counties/pike/news/2015/three-sisters.

Most scientists and researchers shy away from the term companion planting, because it is often more theory than fact. They do, however, use terms such as intercropping and polyculture. Both methods refer to growing two or more dissimilar crops on the same piece of land simultaneously. One difference between the two terms is polyculture often aims at hosting plants that mature at different times of the growing season.

The benefits of a polyculture is in that it more closely mimics natural biodiversity in the ecosystem. This can reduce disease and insect populations, as well as potentially increasing harvest yields.

It turns out that planting squash, pole beans and corn together results in some interesting perks. The corn acts as a trellis giving the beans a place to climb. The beans provide nitrogen for the other two plants. The squash rounds out this trio’s microclimate by providing shade which can reduce weed growth and retain moisture in the soil. Oklahoma Ag in the Classroom also shares “the prickly hairs of the squash vine keep pests away”. http://aitc.okstate.edu/lessons/okstudies/3sisters.pdf.

Cornell University cautions we may have some unexpected results when using the Three Sisters method, such as a decrease in harvest due to not providing additional fertilizer and an overcrowding of plants. A detailed description of how to plant the Three Sisters based on the Iroquois custom can be found on the university website: http://gardening.cals.cornell.edu/lessons/curricula/the-three-sisters-exploring-an-iroquois-garden/how-to-plant-the-three-sisters/.

So is this method of planting theory, tradition or fact? I couldn’t find any research-based, peer-reviewed papers proving the Three Sisters planting method directly benefits the corn, beans or squash when planted together. On the other hand, polyculture plantings have been shown to be beneficial on numerous levels. Regardless of my findings, I think planting the Three Sisters would be a great activity, especially for youth and those interested in learning more about Native American culture.

For more on the legend of the Three Sisters:

https://nysipm.cornell.edu/sites/nysipm.cornell.edu/files/shared/documents/three-sisters-story.pdf.

Kelley Rawlsky has an M.S. in horticulture and is the director of Bringing People and Plants Together, an organization dedicated to bringing horticulture education and therapy to the community. For more information: PeopleAndPlantsTogether@gmail.com or follow us on Facebook.

Article originally published in Broomfield Enterprise - May 20, 2018