What is a 3 Sisters Garden? A "3 sisters" garden is composed of corn, pole beans, and squash. These three vegetables are grown together in one space and compliment each other. Corn grows upright, providing a pole for pole beans to use as a trellis and grow on. Pole beans put nitrogen into the soil, feeding the heavy feeders, corn and squash. Squash grows along the ground in-between the corn and pole beans. Once established, the squash acts as a ground cover, keeping mois