The Three Sisters (Spanish: tres hermanas) are the three main crops grown by many Indigenous groups in Central and North America. These crops are squash, maize (called corn), and climbing beans, such as tepary beans or common beans. Some Native American groups also planted sunflowers near their gardens, calling them the "fourth sister."
A farming method called companion planting is often used. Maize and beans are planted together in mounds made by piling soil around the plants each year. Squash is usually planted between the mounds. The corn stalks provide support for the climbing beans. The beans add nitrogen to the soil and help hold the corn in place during strong winds. The large leaves of the squash plants cover the ground, keeping the soil wet and stopping weeds from growing.
Indigenous peoples across North America grew different types of the Three Sisters that suited their local areas. The crops and their use in growing multiple plants together began in Mesoamerica. There, squash was first grown about 10,000 years ago, followed by maize and then beans over the next 5,000 to 6,500 years. European records from the 1500s describe productive Indigenous farming in what is now the Eastern United States and Canada. These crops were used for food and trade. Geographer Carl O. Sauer called the Three Sisters "a special group of plants in North and Central America that work together in a way not seen anywhere else."
Cultivation methods
Agricultural history in the Americas was different from the Old World because the Americas did not have large-seeded grains like wheat and barley, nor did they have large animals that could help with farming. When Europeans first met Indigenous peoples in the Americas, Carlos Sempat Assadourian wrote that Europeans used "extensive agriculture, based on the plough and draught animals," while Indigenous peoples used "intensive agriculture, based on human labour."
In Indigenous American farming, maize (corn), beans, and squash are often planted close together. Maize and beans are usually planted in mounds made by piling soil around the plants each year, and squash is planted between the mounds. In the northeastern U.S., this method helps raise the soil temperature and improves drainage, which helps maize grow better in spring. Among the Haudenosaunee or Iroquois, fields were not tilled, which helped keep the soil fertile and reduced erosion and loss of organic matter. A modern study found that growing maize, beans, and squash together provided more energy and protein than growing any single crop alone.
Each of the three crops benefits from being grown together. The corn stalks help beans climb, the beans add nitrogen to the soil and hold the corn in place during strong winds, and the wide leaves of the squash plants shade the ground, keeping it moist and reducing weeds. Some squash varieties have prickly hairs that help keep pests like deer and raccoons away.
Although Indigenous cultures long understood the benefits of growing these crops together, scientific proof came much later. Much of this research was done in the Soviet Union in the 1970s and published in a series of books edited by Andrey Mikhailovich Grodzinsky. Studies by Dzubenko & Petrenko (1971), Lykhvar & Nazarova (1970), and Pronin et al. (1970) found that growing legumes with maize improved maize growth and yield. Gulyaev et al. (1970) discovered that certain types of beans grew better when planted with maize. Pronin et al. (1972) found that combining faba beans with maize increased productivity and root exudates, especially in soils with high nitrogen-fixing bacteria activity.
Indigenous peoples across North America grew different versions of the Three Sisters, adapted to local conditions. In Mesoamerica, large farms called milpas used companion planting on a larger scale. The Ancestral Puebloans used this method in dry desert areas. In the North American Southwest, the Tewa and other groups sometimes included a "fourth Sister," the Rocky Mountain beeplant, which attracts bees to help pollinate beans and squash. The Three Sisters farming method was also widely used by many First Nations in the Great Lakes–St. Lawrence Lowlands region.
Productivity
The practice of growing the Three Sisters—maize, beans, and squash—together is often used in small gardens for personal use. However, its historical importance was in large-scale farming that helped entire communities grow food. European records from the 1500s describe highly productive Indigenous farming in what is now the eastern United States and Canada, from Florida to Ontario. The geographer Carl O. Sauer called the Three Sisters "a unique plant system found only in North and Central America." The agronomist Jane Mt. Pleasant explained that the Three Sisters mound system improves soil quality, reduces erosion, helps manage plant spacing, provides needed nutrients, and controls weeds. Over thousands of years, selective breeding made maize, the most important crop in the Americas, more productive than Old World grains like wheat and barley. Maize produced 2.5 times more calories per land area than wheat and barley.
Nutritionally, maize, beans, and squash together contain all nine essential amino acids. The protein from maize is improved by beans and pumpkin seeds, while pumpkin flesh provides vitamin A. Farmers using the Three Sisters system harvest about the same amount of energy as from growing only maize, but get more protein from beans and pumpkins. Mt. Pleasant noted that this system produces more food and supports more people per hectare than growing single crops alone.
Scholars Mt. Pleasant and Burt tested Iroquois farming methods using Iroquoian maize varieties in New York. They found maize yields of 22 to 76 bushels per acre (1.4 to 4.8 tonnes per hectare). Soil quality and weather were the main factors affecting these results. Mt. Pleasant also challenged the idea that the Iroquois used slash-and-burn farming, which involves clearing land and abandoning it when soil becomes poor. Instead, she claimed that Iroquoian no-till methods helped keep soil fertile. In a similar experiment in Minnesota, Munson-Scullin and Scullin found that maize yields dropped from 40 to 25 bushels per acre (2.5 to 1.6 tonnes per hectare) over three years.
Other scholars estimated lower maize yields. Hart and Feranec reported Huron agriculture yields of 8 to 22 bushels per acre (0.5 to 1.4 tonnes per hectare), with higher yields on newly cleared land. The Huron lived in Ontario, where farming was harder due to less fertile soil. Despite this, they produced enough food to trade with neighboring groups. Bruce Trigger estimated that the Hurons needed 0.4 to 0.8 acres (1,600 to 3,200 square meters) of farmland per person for their needs, with more land required for trade. Sissel Schroeder estimated that 19th-century Native American farms averaged 18.9 bushels per acre (1.2 tonnes per hectare), but suggested earlier yields might have been as low as 10 bushels per acre (0.6 tonnes per hectare). Since Native Americans did not plow their land, Mt. Pleasant and Burt concluded that their methods helped retain more organic matter in the soil, leading to higher maize yields than early Euro-American farms.
Society and culture
Maize, beans, and squash have been grown in the Americas for a very long time, whether planted alone or together. Learning how to grow these crops took thousands of years. Squash was the first to be domesticated, followed by maize and then beans. Squash was first grown by people about 8,000 to 10,000 years ago.
The Three Sisters model is more than just a way to grow crops together. It has also been an important part of the culture and beliefs of the communities that used it. Scholars from fields like anthropology, history, agriculture, and food studies have studied and written about the Three Sisters. Most of these studies were done by people who are not from the Indigenous groups that originally created and used this farming method.
Between 800 AD and the time Cahokia was used, the largest Native American city north of the Rio Grande was Cahokia. It was located in the Mississippi floodplain near modern-day St. Louis, Missouri. Cahokia covered more than 13 square kilometers and supported thousands of people. The city had clearly defined areas for government, homes, and farming. At first, people in Cahokia grew domesticated squash, gourds, and maize alongside wild beans. Domesticated beans were not grown there until 1250 AD. The Three Sisters crops helped produce enough food to support Cahokia’s growing population and other cultures in the Mississippi River region, such as the Mississippian and Muscogee peoples.
There is evidence that Cahokia held a large feast between 1050 and 1100 AD. The food served at these events included domesticated squash, maize, and wild beans, along with other plants and animals. Foods that needed preparation, like cornmeal, were often made at the feast site along with items that had ritual or ceremonial importance.
Over time, the land around Cahokia became damaged because of heavy use. As forests were cleared, water ran off the land and flooded fields during the growing season, making it harder to grow the crops that Cahokia relied on. By around 1350 AD, Cahokia was mostly abandoned, though the Mississippian and Muscogee cultures continued to thrive until about 1600 AD, when diseases brought by Spanish explorers caused population decline and cultural changes.
In the Handbook of North American Indians, the Three Sisters are described as the "foundation of (Iroquois) subsistence," helping the Haudenosaunee (Iroquois) develop the systems needed for settled life. The Three Sisters are important in Haudenosaunee traditions, including myths and ceremonies like the Haudenosaunee Thanksgiving Address.
According to a legend, the Three Sisters grew from Earth Woman’s body. During the time of creation, Sky Woman fell to Earth and had a daughter named Earth Woman. Earth Woman gave birth to twin sons with the help of the west wind. The first son, Sapling, was born normally, but his twin brother, Flint, was born too quickly and killed Earth Woman during childbirth. As Earth Woman died, either she wished for her body to help people or Sky Woman planted seeds she had brought from the sky onto Earth Woman’s grave. From Earth Woman’s body, plants like corn, beans, and squash grew from her breasts, hands, and navel, while other plants like sunflowers and strawberries grew from her legs, heart, and feet.
In 1779, Seneca Chief Handsome Lake wanted to die after the U.S. military killed Haudenosaunee people and villagers. After grieving, he saw the spirits of the Three Sisters and decided to teach his people traditional farming methods again.
In the early 20th century, researchers found many varieties of maize, beans, and squash grown by Haudenosaunee communities. The first academic description of the Three Sisters system in 1910 noted that the Iroquois preferred to plant the three crops together because it was easier and because they believed the plants were protected by three spirits that would not allow them to grow apart.
Among the Haudenosaunee, women were responsible for growing and sharing the Three Sisters crops, which gave them a higher social position. Men traditionally traveled for hunting, diplomacy, or military tasks. Men helped prepare the land for planting, and women worked together to plant, care for, and harvest the crops. Archaeological findings suggest that the Haudenosaunee began growing the Three Sisters together as a polyculture after 700 years before the present. Because the Haudenosaunee traded their crops, the need for each crop could change from year to year. Some researchers believe they may have sometimes planted the crops together or separately depending on their needs.
Growing traditional corn remains an important cultural practice for the Haudenosaunee. Today, efforts to preserve this tradition include the Iroquois White Corn Project at Ganondagan State Historic Site in Victor, New York.
The Maya people also relied heavily on the Three Sisters. Maize was the most important part of the Maya diet and played a central role in their myths and beliefs. Archaeological evidence shows that Chapalote-Nal-Tel was the main type of maize grown, though other types were likely used as well.
Folklore
Many legends from Indigenous cultures tell stories about the creation and growth of the Three Sisters crops.
One story shows the crops as three sisters. The first sister, who represents beans, is a young child wearing green clothing. The second sister, who represents squash, is an older child wearing a yellow dress. The oldest sister, who represents corn, is often shown wearing a pale green shawl and having long, yellow hair.
The three sisters are visited many times by a young Indigenous boy. He impresses them with his bravery and skill at hunting, especially archery. Each time he visits, one of the sisters disappears until only the oldest sister remains. She becomes very sad. When the boy returns during the harvest season, he hears her crying and takes her to his parents' lodge to comfort her. There, the oldest sister is reunited with her sisters, who had stayed with the boy out of curiosity. After this, the three sisters never separate again.