The Three Sisters, corn, beans and squash, is one of the oldest and best-known companion planting systems in the world. Indigenous peoples of North America developed it over centuries, and many communities still grow it today.
Each “sister” helps the others, and together they produce a lot of food from a small space. Here’s how it works and how to plant your own Three Sisters garden.
How the Three Sisters Help Each Other
- Corn grows tall and strong, giving the beans a natural pole to climb.
- Beans are legumes. Bacteria on their roots take nitrogen from the air and store it in the soil, which feeds future crops after the plants break down.
- Squash spreads its big leaves across the ground, shading out weeds and keeping the soil moist. Its prickly vines may also discourage some animals.
Grown together, the three crops also make a balanced diet: corn for carbohydrates, beans for protein and squash for vitamins.
What You’ll Need
- A sunny spot: at least 6 to 8 hours of direct sun a day.
- Space: plan for roughly 4 to 5 feet between mound centers, because the squash will spread. A 10 x 10 foot area fits about 4 mounds.
- Corn seed: traditional flour, flint or dent corn is ideal because the stalks are sturdy. Sweet corn works but is weaker, so choose a tall variety.
- Pole bean seed: a climbing type such as Scarlet Runner or a “cornfield” bean. Avoid bush beans, which won’t climb.
- Squash or pumpkin seed: a vining winter squash or small pumpkin.
- Compost to enrich each mound.
How to Plant a Three Sisters Garden, Step by Step
- Wait for warm soil. Plant corn after your last frost, once nights stay above about 50°F (10°C).
- Build the mounds. Make mounds about 12 inches high and 18 inches to 3 feet across, mixing in compost. In dry areas, flatten the top and make a shallow dip to catch water.
- Plant the corn. Soak corn seed for a few hours, then plant 4 to 7 seeds about 6 inches apart in the center of each mound. Later, thin to the 3 or 4 strongest seedlings.
- Wait for the corn to grow. Let the corn reach at least 6 inches tall before planting the beans. If beans go in too early, they can pull down the young stalks.
- Plant the beans. Sow about 6 pole bean seeds in a circle roughly 6 inches out from the corn. Thin to 3 or 4 plants.
- Plant the squash. At the same time, plant about 4 squash seeds around the outer edge of the mound, about a foot from the beans. Thin to the 1 strongest plant.
- Guide the beans. As they grow, gently wrap the bean tendrils around the corn stalks.
Caring for Your Three Sisters
- Water deeply at the base of the mounds, especially while the corn is forming tassels and ears.
- Weed early. Pull weeds until the squash leaves cover the ground, then let the squash do the work.
- Watch for pests such as squash vine borers and squash bugs. Check the undersides of leaves and the base of the vines.
- Harvest in stages. Pick green beans while young, or let them dry on the vine for dry beans. Harvest corn when the silks turn brown, and winter squash when the rind is hard.
Three Sisters in a Small Garden or Raised Bed
No big plot? Grow a single mound in a 4 x 4 foot raised bed, or let the squash trail over the edge of the bed. Choose a compact bush-type winter squash and a shorter pole bean to keep things manageable.
Common Problems and Fixes
- Beans pulling corn over: plant beans later, after the corn is established, and use fewer bean plants per mound.
- Poorly filled corn ears: corn is wind-pollinated. Plant several mounds close together in a block, not one long row.
- Squash taking over: gently redirect vines away from the corn, or choose a less vigorous variety.
Want more pairings? See our companion planting chart for vegetables, and learn which plants shouldn’t be grown together.
Frequently Asked Questions
Can I use sweet corn for the Three Sisters?
Yes, but sweet corn stalks are thinner, and you’ll pick the ears before the beans finish. Choose a tall, sturdy variety and limit the beans to 2 or 3 per mound.
Is there a fourth sister?
Some traditions add a fourth plant, such as Rocky Mountain bee plant or sunflowers, to attract pollinators. Keep sunflowers at the edge, because they can shade and compete with the corn.
When should I plant the Three Sisters?
In late spring, after frost has passed and the soil has warmed. Plant beans and squash about 2 weeks after the corn, once the corn is about 6 inches tall.
