An agricultural staple of the North American Native American diet was the intercropping of squash, beans, and corn. The combination of these plant types was so important to Native American culture that it took on a spiritual nature. In the Iriquois mythology, squash, beans, and corn are three inseperable sisters who must grow together and depend on each other for survival. The Three Sisters agricultural technique was practiced by Native Americans from Mesoamerica all the way to the Great Lakes in Michigan.
The Three Sisters intercropping system is efficient both ecologically and nutritionally. Typically the three plants are planted together at the top of a raised mound. The corn provides a tall sturdy base for the beans to climb allowing them access to sunlight; the beans in turn fortify the corn stalk making it less vulnerable to wind. The squash leaves grow and spread along the ground which blocks sunlight from reaching the earth creating natural weed suppression. The shade provided by the squash leaves also creates a cool microclimate under the canopy of the leaves and helps the soil retain moisture allowing roots access to water for a longer period of time. Beans fix nitrogen into the soil, which provides added nutrients for the squash and corn plants. Some tribes add a fourth sister, a bee plant, which attracts pollinators to the plants and adds to the ecological richness of the intercropping. This symbiotic planting will allow all three crops to extend their growing season while using less water and nitrogen imputs.
Nutritionally, this is an efficient combination because beans contain amino acids that are lacking in the corn plant. When eaten together they create a more balanced diet (http://en.wikipedia.org/wiki/Three_Sisters_(agriculture).
If you would like to plant your own Three Sisters garden, follow the design provided by Renee’s Garden in the following link: http://www.reneesgarden.com/articles/3sisters.html