The Three Sisters are the three main agricultural crops of Native Americans in North America: squash, maize (or corn), and climbing beans.

In a technique known as companion planting, the three crops are planted close together:

1. build flat-topped mounds of soil for each "cluster", about a foot high and 20 inches wide
2. plant several corn seeds close together, in the very center
3. when the corn is 6 inches tall, plant beans and squash around the corn, alternating between beans and squash

The three crops benefit from each other:

• The corn provides a structure for the beans to climb, eliminating the need for poles.
• The beans provide the nitrogen to the soil that the other plants remove.
• The squash spreads along the ground, monopolizing the sunlight to prevent weeds.
• The squash also acts as a "living mulch," creating a microclimate to retain moisture in the soil.