The Three Sisters are the three main agricultural crops of some Native American groups in North America, particularly in New England: squash, maize, and climbing beans (typically tepary beans or common beans).
In a technique known as companion planting, the three crops are planted close together:
- Flat-topped mounds of soil are built for each "cluster", about 30 cm (1 ft) high and 50 cm (20 in) wide.
- Several maize seeds are planted close together, in the very center of each mound.
- When the maize is 15 cm (6 inches) tall, beans and squash are planted around the maize, alternating between beans and squash.
The three crops benefit from each other:
- The maize 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.
In some parts of New England, a fish was often planted with the maize seeds, to act as additional fertilizer where the soil was poor.