The Three Sisters garden is an ancient Native American method of gardening using a system which grows corn, beans, and squash crops simultaneously in the same growing area, often called a hill. It goes back to the Iroquois people who thought about the elements of nature while planting. If you want to use traditional methods, plant the seeds with kind thoughts 3 days before Full Moon.
Corn is the oldest sister. She stands tall in the center. This could be corn for grinding into cornmeal, sweet corn or popcorn.
Squash is the next sister. She grows over the mound, keeping her sisters from weeds and shades the soil from the sun with her leaves, keeping it cool and moist. This can be winter squash, summer squash like zucchini or pumpkins.
Beans are the third sister. She climbs through squash and then up corn to bind all together as she reaches for the sun. Beans help keep the soil fertile by converting the sun's energy into nitrogen filled nodules that grow on its roots. As beans grow they use the stored nitrogen as food. This can be shelling beans that are harvested when dry and used in baked beans and bean soups or fresh green beans that are climbers.
In mid-Spring clear a sunny garden area of grass, weeds, and large stones. The area should be at least eight feet across. If you have access to compost or well rotted manure, add this to the garden.
In late-Spring after the soil has warmed, sow about seven or eight corn seeds in the center of the growing circle, spaced out about six inches from each other. Plant the corn seeds an inch under the soil, firm the soil above by patting it down with the palm of your hand. Water well. The corn will sprout and begin to grow in about two weeks.
After the corn has grown to about ten inches high, sow about a dozen pole bean seeds in a ring pattern six inches outside the corn stalks. Push the bean seeds about an inch under the soil and firm the ground above them by patting it down with your hand. Water well. The beans will usually begin to sprout in about 7-14 days.
About a week after the beans sprout, sow six or seven squash seeds in a ring about 12-15" outside the beans. Push the squash seeds about an inch under the soil and firm the ground above them by patting it down with your hand. The squash seeds will sprout in about a week.
As the corn grows the beans will begin to climb around the corn stalks. The squash will begin to grow its vines and the squash leaves will soon cover and shade the soil. Water well during weeks where there has been little or no rain.
To find heirloom seeds for corn, squash and beans, please see http://www.seedsavers.org.