Three Sisters Planting Guide: Corn, Beans, and Squash
How to plant a Three Sisters garden: corn first on a mound, pole beans when the corn is about 6 inches tall, and squash around the outside. Spacing, timin...
Published by ThriveThyme
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Three Sisters Planting Guide
Plant corn first on a wide mound. When the corn is about 6 inches tall, plant pole beans around it and squash around the outside. Corn holds up the beans, and squash leaves shade out weeds. This is one of the few companion plantings with clear reasons behind it.
The Three Sisters is an Indigenous planting method used across North America and Mesoamerica for centuries. It is still the base of milpa farming today.
What Each Crop Does
- Corn is the pole. Its stalk gives the beans something to climb.
- Pole beans climb the corn. Beans fix nitrogen in their roots, but most of it stays with the bean until the roots break down. Corn still needs its own fertilizer the first year.
- Squash or pumpkin covers the ground. Big leaves shade the soil, hold moisture, and crowd out weeds. Prickly vines may also keep raccoons off the corn.
When to Plant
All three are frost-tender. Plant after your last spring frost, once soil is about 60 F. Find your date on the first frost date page. Do not rush it: cold soil rots corn and bean seed.
How to Plant One Mound
- Pick a spot with 6 to 8 hours of sun and access to water.
- Build a mound about 12 inches high and 18 inches to 3 feet wide. Space mounds 3 to 4 feet apart. In dry areas, flatten the top and press a shallow dip so water soaks in.
- Plant 4 to 7 corn seeds about 6 inches apart in the center. Thin to the 3 or 4 strongest.
- When the corn is about 6 inches tall, plant about 6 pole bean seeds in a circle 6 inches out from the corn. Thin to 3 or 4.
- At the same time, plant 4 squash or pumpkin seeds about a foot outside the beans. Thin to 1 plant.
- Water about 1 inch a week if it does not rain.
- Side-dress the corn with compost or fertilizer when it is knee-high and again when silks show.
Pick the Right Varieties
- Corn: tall field, flint, or flour corn holds bean weight best. Short sweet corn can fall over under heavy vines.
- Beans: pole beans, not bush beans. Bush beans will not climb.
- Squash: vining winter squash or pumpkins. Bush zucchini does not spread enough to shade the ground.
Common Problems
- Beans planted with the corn seed. Fast beans pull small corn over. Wait for 6 inches of corn.
- No fertilizer. Corn is a heavy feeder, and bean nitrogen does not reach it in time.
- Too-close mounds. Squash vines run several feet. Give them room or train them back toward the mound.
- Tall sunflowers in the middle. If you add them, plant them on the north side so they do not shade the mound.
Check corn, bean, and squash pairs on the Companion Planting Desk. Plant pages: sweet corn, pole bean, and butternut squash.
Sources: Cornell Cooperative Extension, Creating a Three Sisters Garden; University of Minnesota Extension, Companion planting in home gardens; Oregon State University Extension, Tips for planting corn, beans and squash.