Familiar to many gardeners is the Native American triad of corn, beans, and squash, a combination often called the Three Sisters. The trio qualifies as a guild because each of these plants supports and benefits the others. The cornstalks form a trellis for the bean vines to climb. The beans, in turn, draw nitrogen from the air, and via symbiotic bacteria convert the nitrogen to plant-available form. These nitrogen-fixing bacteria, scientists have recently learned, are fed by special sugars that ooze from the corn roots. The rambling squash, with its broad leaves, forms a living parasol that densely covers the ground, inhibiting weeds and keeping the soil cool and moist. Together the Three Sisters produce more food, with less water and fertilizer, than a similar area planted to any one of these three crops in isolation.
This guild bears many interconnections:
- Beans furnish nitrogenous fertility for themselves, corn, and squash;
- Squash shades soil for the benefit of all three;
- Corn feeds the bean-hugging bacterial nodules and creates a trellis for the beans.
The Three Sisters guild is a perfect place to begin creating a richly connected garden.
- Mark out a series of planting holes about 3 feet apart (to calculate how many holes you need, figure that you’ll get about four or five ears of corn per hole).
- Then poke three or four kernels of corn into each hole (some suggest to soak four to seven corn seeds overnight), and cover with an inch of soil.
- When the corn sprouts, start mounding the soil up around the young stalks. Don’t cover the sprouts; just build up earth around the base. These mounds, by exposing soil to the air and sun, will warm the sprouts, speeding their growth. The mounds also improve drainage. Don’t thin the corn you want two or three stalks per mound, hence the greater-than-usual distance between mounds.
- About two weeks after planting the corn, select some pole beans—not a bush variety and coat the seeds with a legume inoculant specific for beans (available from many seed suppliers). This ensures that the all-important nitrogen-fixing bacteria find a happy home among the bean roots. Plant two or three bean seeds into each corn mound.
- At the same time you start the beans, plant squash or pumpkins between each mound. Don’t use zucchini; grow a vining squash variety that will sprawl over the soil.
- After harvest, leave the stalks, vines, and other organic debris on the ground to compost in place. This returns some of the extracted fertility to the soil and protects the ground from erosion. Although much of the bacterially fixed nitrogen will be concentrated into the protein-rich bean pods, plenty will remain in the vines and roots, ready to go back to the earth.
As an alternative to the Three Sisters combo, the sunflower stands as a substitute for the corn. It is certainly sturdy enough to hold its own against a vine. And when the center opens to reveal its thousands of seeds, we can leave them for the birds.
A fourth sister was also employed, Spider Flower (Cleome spp.). Cleome is quite aromatic with a magnificent flower; these traits attract beneficial pollinators, and the spiny stems further protect neighboring crops.