Corn, beans and squash were the three main agricultural crops of many Native American groups in the continental United States. Known as The Three Sisters, growing these crops together -- as the Native Americans are believed to have inspired Colonial farmers to do -- demonstrates an agricultural strategy known as Companion Planting.
Here's how it works. The Corn stalks provide structure for the pole beans to climb. The Bean roots fix nitrogen in the soil for the Corn and Squash. And the Squash plants spread along the ground like a living mulch, blocking the sun, retaining moisture in the soil, discouraging weeds and deterring pests with prickly hairs of their vines. In this way, the three crops not only occupy the same plot, but also synergize, enhancing the growth of one another.
Robbins Farm Garden introduced a Three Sisters plot in 2011, and is featuring one again this year. This is in happy coincidence with the Arlington Historical Society's 3rd Grade Educational Program on Colonial Life, which includes The Three Sisters. Colonial farmers adopted The Three Sisters planting strategy from the Algonquin, the Native Americans who originally inhabited this land. In Colonial times, Arlington was known by the Algonquin name Menotomy.
In 2011, our Three Sisters plot contained Double Standard Heirloom Corn, Garden of Eden Italian Pole Beans and Chucky F1 Pumpkins. We were unaware that the Corn should be planted first, followed when it is six inches tall by the Beans and Squash. When planted all at once, as we did that first year, the Beans outgrew the Corn and required staking. This, as well as a desire to try different Corn and Squash varieties, led to a few changes in our 2012 Three Sisters plot.
This year, we planted only the corn, Miniature Colored Popcorn on May 12. We will follow when the corn has reached six inches in height, with Garden of Eden Italian Pole Beans again (they did exceptionally well in 2011 and were delicious) and JWS 6823 PMR F1 Butternut Squash. Butternut Squash were selected because they are less susceptible to Squash Vine Borers than most Squashes. The borers can be extracted from the vines, but the lack of access created by the Corn and Bean plants make this disagreeable procedure more difficult.
Nutritionally, The Three Sisters also work well together. In combination with Beans, Corn and Squash contain all the nutrients necessary to produce proteins and niacin. Combining the Three Sisters with other seasonal herbs and vegetables in a stew is a traditional treat. All three crops can also be stored without refrigeration. Corn and Beans can be dried, and undamaged winter Squash will keep for many months in cool, dry conditions.
Variations of Three Sisters abound. Pueblo tribes of the US Southwest adapted the companion planting to a drier environment, often including a Fourth Sister known as Rocky Mountain Beeweed to attract bees to pollinate the Beans and Squash.