Three sisters planting

The Three Sisters Garden is a wonderful example of relationships in the garden. From a scientific, agricultural perspective these relationships are between particular families of plants, legume family (beans, peas), the grass family (corn) and the gourd or curcubit family (squash, pumpkins and melons).

The "three sisters" are maize/corn (Zea mays), beans (Phaseolus vulgaris L.) and squash (Cucurbita spp.). According to historical records, the farmer dug a hole in the ground and placed one seed of each species into the hole. The maize grows first, providing a stalk for the beans, which reach upward for access to the sun. The squash plant grows low to the ground, shaded by the beans and corn, and keeping the weeds from affecting the other two plants.

Today, intercropping in general is recommended as an alternative system for small-scale farmers to improve their yield, and thus food production and income in limited spaces. Inter-cropping is also insurance: if one of the crops fail, the others might not, and the farmer is more likely to get at least one of the crops to produce in a given year, no matter how extreme the weather circumstances.

The microclimate produced by the three sisters combination favors the survival of the plants. Maize is notorious for sucking the nitrogen out of the soil; beans, on the other hand, supply replacement mineral nitrogen back into the soil: essentially, these are the effects of crop rotation without actually having to rotate crops. Overall, say crop scientists, more protein and energy are produced by intercropping three crops in the same space than that achieved by modern monocultural agriculture.

Maize maximizes photosynthesis, and grows straight and tall. Beans use the stalks for structural support and to gain greater access to sunlight; at the same time they bring atmospheric nitrogen into the system, making the nitrogen available to maize. Squash performs best in shady, humid places, and that is the type of microclimate provided by the corn and beans together. Further, squash decreases the amount of erosion that plagues monocultural cropping of corn.