According to Iroquois legend, corn, beans, and pumpkin are three inseparable sisters who only grow and thrive together. This tradition of inter-planting corn, beans and pumpkin in the same mounds is a sophisticated, sustainable system that provides long-term soil fertility and a healthy diet to generations.
Corn provides a natural pole for bean vines to climb. Beans fix nitrogen on their roots, improving the overall fertility of the plot by providing nitrogen to the following years corn. Bean vines also help stabilize the corn plants making them less vulnerable to blowing over in the wind. Shallow rooted pumpkin vines become a living mulch, shading emerging weeds and preventing soil moisture from evaporating, improving the crops chances of survival int he dry. Spiny pumpkin plants also help discourage predators from approaching the corn and beans. (In literature the predators quoted are often Raccoons. In this respect The Three Sisters has worked extremely well – I have not seen a single Raccoon in my garden or anywhere else in CHB! You’re welcome. 😆 )
The large amount of crop residue from this planting combination can be incorporated back into the soil at the end of the season (chop and drop), to build up the organic matter and improve its structure.
Corn, beans and pumpkin also complement each other nutritionally. Corn provides carbohydrates, the dried beans are rich in protein, balancing the lack of amino acids found in corn. Finally, pumpkin yields both vitamins from the fruit and delicious oil from the seeds.
Success with The Three Sisters involves careful attention to timing, seed spacing, and varieties. If you simply plant all three in the same hole at the same time the result will be a snarl of vines in which the corn gets overwhelmed.