Planting the "Three Sisters" is a companion planting technique which was heavily utilized by Native Americans for hundreds of years. Corn, beans and winter squash are the "Three Sisters". Companion planting is simply grouping plants together that benefit each other in some way. Beans affix nitrogen into the soil, corn is a heavy feeder. Planting beans with corn provides the corn with nitrogen and the corn in turn provides the beans with a structure to climb on. The prickly vines of the winter squash helps keep critters away from the corn. Planting corn, beans and winter squash together also helps when there isn't a lot of gardening space.
Things You Will Need
Winter Squash, any of the squash family will work, we use pumpkin
Choose a sunny location and prepare the soil. Soil should be loosened up to 18 inches and organic matter mixed in. Corn needs a lot of space, a minimum of 16 foot by 16 foot area.
Plant corn seeds in groups of two to three. Thin plants when they reach about 4 inches. Choose the healthiest corn plant. It needs to be planted in at least 4 rows of four with three feet between rows. This is necessary for pollination. It does not transplant well and all plants need to be the same "age" so growth stages are similar when it's pollination time. It should be watered deeply to encourage deep rooting for stability.
Once corn has been thinned, plant beans six inches from it. Watch the growth of the beans and train them to vine up the corn plant. Once beans have started to produce, they should be checked daily. If they are not picked when ready, the plant will stop producing. Daily harvesting also allows you to notice any potential problems with the other vegetables. The beans will trap nitrogen in the soil for the other vegetables.
At the same time you plant the beans, plant your choice of winter squash. Plant winter squash in between the corn rows. Let the vines ramble around. The prickly vines of the winter squash discourage many pests. Don't let the vines grow up the corn as they can damage the stalks.
Days until harvest depend on what type of corn you have planted. It can take anywhere from 65 - 95 days to harvest corn. Depending on variety, winter squash will take anywhere from 100 - 160 days until ready for harvest. Beans are ready much sooner and can continually be harvested until the plant dies. Planting the "Three Sisters" together will have allowed for more utilization of space and a better harvest due to companion planting benefits.
Tips & Warnings
A note about corn: As soon as it is picked, its sugars start to turn to starch. It should be picked and cooked right away. If it isn't going to be cooked right away, pick it in the morning when they are at their sweetest.
Most winter squashes can be stored for a surprising amount of time in a cool spot. Time and conditions vary by type.