Planting a Three Sisters Garden
Experimenting with Companion Planting

Debby Luquette
Adams County Master Gardener

(4/20) Companion Planting has always been a gardening interest of mine. Afterall, when have you walked into a forest or field and noticed that all the plants are the same species? I can only think of one natural ‘monoculture’ – expanses of Salt Marsh Cordgrass growing along temperate ocean shorelines. Even in these marshes, there are other inhabitants – plants, insects, birds, and other wildlife. True monocultures only seem to exist where humans have machines and chemicals to maintain them. Nature loves variety.

That makes companion planting an ecological gardening technique that mimics nature. Nature doesn’t grow plants in straight rows of the same species. In temperate areas with adequate rainfall, like Adams County, the natural climax growth is a forest, with a wild array of many species of plants, animals and fungi that have become companions over time.

When the first humans – the First Americans – moved into this area after the retreat of the last Ice Age, their diet was taken from Nature’s provision. As the climate stabilized, the vegetation and wildlife adapted, too. The people inhabiting the Americas also adapted; they began to establish gardens from the seeds and cuttings of plants they found most useful. Trade among various tribes flourished, bringing the seeds of corn, beans, and squashes north and east from Central and South America. Eventually, the Three Sisters emerged as an agricultural method.

The Three Sisters is a companion planting technique that combines corn, pole beans and vining squashes and pumpkins in a way that allows each plant to take advantage of traits of the other two. This mimics a forest, where tall trees support vines and understory plants shelter the ground. The corn supports the vining pole beans. The squashes and pumpkins, with their broad leaves and ability to take up space, cover the ground to suppress weeds and evaporation of water.

Like all legumes, pole beans form a relationship with a particular soil bacterium, Rhizobium. This bacterium colonizes the roots and uses nitrogen from the air and turns it into a form the beans can use. Leaky bean roots and dropped bean foliage allow some of this nitrogen fertilizer to escape into the soil and add a nutritional boost to the corn and squash.

While there is reasonable scientific logic to this plant grouping, there is another reason to use this plant combination. With fertile soil, especially if it is enhanced with organic matter, this grouping is impressively productive and nutritious. Anthropologic and historic records show that the Pilgrims landing in Massachusetts were taught by a Wampanoag tribesman to plant the Three Sisters in groupings on mounds, not in rows. The colonists were shown how to cultivate with hoes and to work with and around the plants by hand.

The Pilgrims that made it through the first two winters were well on their way due in large part to the nutritional value of this corn, beans, and squash diet, supplemented by game and seafood. As more colonists reached these shores with their plows and wheat seeds, the Pilgrims reverted to their comfortable English diet.

Research conducted by Jane Mt. Pleasant of Cornell University demonstrates the nutritional value of the corn-beans-squash diet over the wheat-based diet. (When speaking of corn in this context, it refers to ‘field corn,’ not sweet corn.) The protein and vitamin value of these crops as the main part of the diet exceeds that of a diet based on wheat.

As food crops today, one can consider the Three Sisters as ‘dietary staples,’ supplementing the more common foods we enjoy. For a modern diet with more variability, this includes growing other foods – peppers, tomatoes, brassicas, greens, etc. And do not forget beneficial insect-attracting flowers and herbs in the garden.

Planting a Three Sisters Garden is not hard. There are several layouts which work well. The Wampanoag scheme is several rows of round 2-foot mounds, spaced 2 feet apart. Your plot could be as small as four rows of five mounds each, including aisles, filling an area approximately 20 feet by 15 feet. Additional room is needed for squash mounds added at the end of the row. One could also expand the size of the plot by adding mounds for squash within the corn-bean mounds. Remember that corn is wind pollinated, so there needs to be a somewhat dense planting to achieve good corn pollination.

There are online pages that have diagrams and descriptions of other layouts. The resource I used is a family-friendly book, Native American Gardening by Michael Caduto and Joseph Bruchac, which includes stories and gardening related projects for children, in addition to garden instructions.

Be sure to find varieties of corn, beans, and pumpkins or winter squash you enjoy eating and work well together. This might take more than one growing season. To support the beans, the corn needs to be tall and strong; look for a late variety. Because of the rapidly warming soil we are experiencing now, corn needs to be planted in early May. The beans and squash are planted after the corn has 4 or 6 leaves, about 2˝ weeks later. Be sure to water if the summer is hot and dry.

Once you find varieties of corn and beans you like, if there are no other varieties growing nearby, consider saving their seeds. Allow a few ears and pods of your best, strongest plants to dry on stalk and vine and save these seeds. Personally, I like several summer and winter squash varieties, but because they cross pollinate readily and hybridize easily, I do not save these.

The varieties I planted last year are pictured: pumpkin – Long Island Cheese; beans – Kentucky Cornfield (saved seed); and red field corn, Bloody Butcher. The corn was milled with a reasonably priced mill attachment for a stand mixer. Enjoy the adventure.

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