-The three sisters of Corn, Beans and Squash are a traditional polyculture grown by many indigenous cultures across North America. All three sisters are interdependent and help the others grow; the corn supports the climbing pole beans, the beans add nitrogen to the soil, and the squash sprawl over the surface of the soil shading out competing weeds.
-To grow a three sisters garden I find it’s best to plant the seeds in hills, which traditionally would be enriched with fish waste for a nutrient boost. I usually enrich the hills with composted manure myself, since it’s what I have on hand. I make mine about 1‘ high and perhaps twice as wide, with a flattened or bowl shaped top (so water can collect and seep in). To give the plants enough space, hills should be about 4’-5‘ feet apart, from centre to centre. In a small garden hills could probably be closer, as long as the beans and squash have access to sunlight. There aren't any set rules, definitely experiment! A mistake I’ve made in the past is to plant things too densely, in which case the corn grew and thrived but it didn’t allow enough light in for the other two sisters.
In the middle area of the hill, I plant 4-6 corn seeds, and around the outside a similar number of squash. I plant them in late May or early June, after the risk of frost is past for us. The corn gets a 2-3 week head start, and then the beans go in at the base of the young corn seedlings. That way the fast growing pole beans don’t overwhelm the slower corn. You’ll want to eventually thin each hill to 3-4 healthy corn plants.
Hills with transplanted squash and recently sown corn, waiting for beans. - Hills in full abundance, mid-August (photo by Chris Sanford)
-If you’re up for experimenting, other crops can make great additions to the polyculture also. Both amaranth and sunflowers have been traditionally grown either alongside or as a replacement for the corn, and I’ve had success using cucumbers as the ground cover instead of squash.
Our three sisters garden is always one of the summer highlights at the farm. After comparing yields for the area that it takes up, I’m even more impressed by how productive a system it is. The individual yields of each crop might be down somewhat from what each one would produce planted as a monocrop, but the fact that we’re getting three crops in the same space makes it extremely space efficient. Comparing a 30’ x 30’ plot of Three Sisters to an equal sized plot of each individual crop, we harvest something like 75% the corn yield, and perhaps 50% of the beans and squash. But add those up and you get much more yield than any one crop on it's own. All the while being a much more resilient and diverse garden, and needing much less human input.