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Three Sisters Grow Bag Garden

By: Angela Judd | February 15, 2025

How to Grow Corn, Beans, and Squash (and Alternatives) in 20-Gallon Containers

If you’ve ever wanted to try the famous “Three Sisters” planting method but were short on space, a 3 Sisters Grow Bag Garden may be just the solution. Traditionally grown in a shared plot, the Three Sisters— corn, beans, and squash — can also thrive together in 20-gallon (about 75 liters) grow bags. By adding an olla for efficient watering, you can keep your container garden healthy even in hot, dry climates. Below, I’ll cover the basics of the Three Sisters: how to adapt them to a grow bag, when to plant each crop, and alternatives to corn if you prefer a different “sister.”

Article Index:

What Is the Three Sisters Planting Method?
Grouping at Least Three Grow Bags for Corn
Alternatives to Corn in a Three Sisters Container Garden
Advantages of Each Option
Three Sisters Planting Times by Climate
Three Sisters Step-by-Step Guide: Planting in Each 20-Gallon Grow Bag
Care & Maintenance for Three Sisters Container Gardens
FAQ: Your Common Questions Answered
Final Thoughts: Enjoying Your Homegrown “Sisters” Container Garden
References

What Is the Three Sisters Planting Method?

Indigenous peoples across North America have used the Three Sisters planting method for centuries.¹ Here’s how it works:

Corn grows tall, providing a natural trellis for climbing beans.
Beans fix nitrogen in the soil, which benefits the other plants.
Squash sprawls around the base, shading the soil to retain moisture and discourage weeds.

Get seeds for the Three Sisters here.

The synergy among these plants means each “sister” contributes something valuable to the others. This is the original companion planting method. Learn more about the benefits of companion planting in this guide.

Grouping at Least Three Grow Bags for Corn

If you plan to grow corn, it is best to use at least three grow bags clustered together. Corn relies on wind pollination; a single bag or even two bags often won’t provide enough pollen transfer for full ears. If you only have space for one or two bags, consider a corn alternative like amaranth, okra, or sunflowers.

An additional benefit of growing multiple bags is the insulating effect grouping them close together can have. By placing them side by side, the bags help shield one another from extreme temperature fluctuations and reduce moisture loss, which is particularly beneficial in hot, dry regions. This cooperative microclimate helps keep roots cooler and soil more consistently hydrated, promoting healthier plant growth overall. Learn more about how to garden in grow bags in this guide.

Alternatives to Corn in a Three Sisters Container Garden

While corn is a traditional “sister,” growing a small amount can make it challenging to achieve proper pollination. Amaranth, okra, and sunflowers make excellent tall “sister” stand-ins. Corn growing guide.

Amaranth is a showstopper with its bright flower heads, and you can harvest both the leaves and seeds. It also handles the heat like a pro, so it’s a great pick if you’re gardening in a warm region like the low desert of Arizona. Amaranth growing guide.

Get amaranth seeds here.

Okra is another heat-loving plant that grows tall and sturdy, giving beans plenty to climb on. It’s known for producing pods all season, provided you harvest them regularly. If you’re sensitive to the tiny spines on the pods, wearing gloves during picking can make your life much easier. Okra growing guide.

Get okra seeds here.

Sunflowers, meanwhile, bring a gorgeous pop of color and produce seed heads you can snack on or share with birds. The catch is their tendency toward allelopathy, meaning they release substances that can inhibit the growth of nearby plants. A study in the journal Plants confirms this effect can impact neighboring crops if they share soil or grow too close.² To minimize issues, look for branching sunflower varieties bred for cut flowers and refresh or amend your soil each season. Sunflower growing guide.

Get branching sunflower seeds here.

Advantages of Each Option

Corn: Traditional approach, strong trellis, tasty harvest of fresh ears.
Amaranth: Heat-hardy, attractive, and yields nutritious greens and seeds.
Okra: Ideal for hot climates, it produces a steady harvest of pods.
Sunflowers: Beautiful blooms, seeds for snacks or wildlife, but keep an eye on allelopathic effects.

Three Sisters Planting Times by Climate

Cool Climates (Zones 3–5): Sow corn (or alternative) in late spring (May) after the last frost. Plant beans two weeks later and squash around the same time as beans.
Moderate Climates (Zones 6–8): Start corn (or an alternative) from late April to early May. Once the soil warms, add beans and squash by mid-to-late May.
Warm Climates (Zones 9–10, including Low Desert of Arizona):
- First round: Plant corn in late February to early March. Beans and squash by mid-March.
- Second planting: Late summer (August) if conditions allow.

Three Sisters Step-by-Step Guide: Planting in Each 20-Gallon Grow Bag

1. Preparing the Container

A 20-gallon grow bag provides enough depth and width for corn, beans, and squash roots to coexist. One 20-gallon bag can hold one “set” of Three Sisters. These are the grow bags I use.

Soil Mix: Fill each 20-gallon bag with high-quality potting mix combined with compost or well-aged manure. Leave about 2 inches (5 cm) of space from the top. I use the raised bed mix from Arizona Worm Farm in my raised beds and containers.
Olla (Optional): If you live in a hot, dry region, place an olla (a porous clay pot) in the center before adding soil. Keep the neck exposed so you can fill it with water. Purchase ollas here. (You can use any size. I usually use the medium or large olla in the 20-gallon grow bags).

Why Use an Olla?

Saves water by delivering it directly to the root zone.

Reduces evaporation, which is a real plus in hot, dry climates such as the low desert of Arizona.

2. Plant Corn (or Alternative)

Number of Seeds per Bag: 4–5 seeds.
Depth: 1 inch (2.5 cm).
Spacing: Evenly around the center, 6–8 inches (15–20 cm) apart.
Timing: Sow after your last frost date, when nighttime temperatures stay above 50°F (10°C).

Alternatives to Corn:

Amaranth: Plant 1-3 per bag.
Okra: Plant 1-2 per bag.
Sunflowers: Plant 2-3 single-stemmed varieties or one branching variety per bag. Branching varieties reduce allelopathic issues (2).

3. Add Pole Beans

Learn more about how to grow beans in this guide.

Number of Seeds per Bag: 4–6 seeds total.
Depth: 1 inch (2.5 cm).
Spacing: Plant each bean seed a few inches from the base of each tall plant so it can climb.
When to Plant: About two weeks after corn (or alternative) germinates, when corn stalks are ~6 inches (15 cm) tall.

4. Plant Squash

Learn more about how to grow squash in this guide.

Number of Seeds per Bag: 2–3 seeds. Thin to strongest seedling.
Depth: 1 inch (2.5 cm).
Spacing: Near the perimeter of the grow bag, leaving room for vines to sprawl.
When to Plant: Same time as beans or within a week afterward.

Care & Maintenance for Three Sisters Container Gardens

Watering
- Fill the olla and water the soil each time. In hot weather, check daily.
- Top the soil with mulch to reduce evaporation. Learn what to use for mulch in this guide.
Fertilizing
- While beans do fix some nitrogen, corn and squash are heavy feeders.
- Use a balanced organic fertilizer or add compost every few weeks.
Pollination Help
- If growing corn, gently shake the stalks when tassels appear to help disperse pollen.
- Group at least three bags for better wind pollination.
Pest & Disease Watch
- Common issues: aphids, squash bugs, powdery mildew.
- Practice good air circulation and remove diseased leaves promptly.
Harvest
- Corn: Kernels should release a milky fluid if pierced, and silks turn brown.
- Beans: Harvest when the size of a pencil. Pick often to encourage new pods.
- Squash: Harvest summer squash young (tender skin); let winter squash mature until skins are hard.
- Okra: Pods at 3–4 inches (8–10 cm).
- Sunflowers: Cut blooms for bouquets or let seeds mature for roasting/bird feed.

FAQ: Your Common Questions Answered

Can I plant multiple Three Sisters grow bag garden sets side by side?
Yes. Placing bags close together helps if you’re growing multiple corn plants for better wind pollination.
Can I grow bush beans instead of pole beans?
Absolutely. Bush beans don’t need a tall trellis, but you’ll lose the vertical climbing aspect. Still, they can complement corn or other tall alternatives.
Can I use black-eyed peas, asparagus beans, or tepary beans instead of pole beans?
Yes! Black-eyed peas, asparagus beans (yardlong beans), and tepary beans are all excellent heat-tolerant alternatives to traditional pole beans. Black-eyed peas and tepary beans are well adapted to arid conditions, making them a great choice for hot, dry climates. Asparagus beans thrive in warm weather and grow long, slender pods that can easily climb corn, amaranth, okra, or sunflowers. Just like pole beans, all of these options will help fix nitrogen in the soil, benefiting the other plants in your grow bag.

If you’re growing black-eyed peas, asparagus beans, or tepary beans, check out my guides on how to grow black-eyed peas, asparagus beans, and tepary beans for specific planting and care tips.

More FAQ about Three Sisters grow bag gardens

Is one 20-gallon bag enough if I plant corn?
Aim for three or more grow bags of corn for best pollination and bigger yields. If you have limited space, consider using a corn substitute like okra, amaranth, or sunflowers in a single bag.
Do I need to thin my seedlings?
Yes, if more than 4–5 corn or tall alternative seedlings come up in one bag, thin them to avoid overcrowding. The same goes for beans and squash; keep the healthiest seedlings.
How often do I refill the olla?
It depends on your climate. In very hot weather, check it daily. In moderate conditions, once or twice a week is often sufficient.
What if I only have a 15-gallon bag?
You can still try a mini Three Sisters but plant fewer seeds (perhaps 3 corn/alternatives, 2 beans, and 1–2 squash). Keep an eye on root space and water needs.
Aren’t sunflowers toxic to other plants?
Sunflowers can be allelopathic, meaning they release chemicals that may inhibit neighboring plants’ growth. Choose less allelopathic varieties and refresh your potting mix each season to reduce these issues.

Final Thoughts: Enjoying Your Homegrown “Sisters” Container Garden

Whether you stick to the traditional corn, beans, and squash or experiment with amaranth, okra, or sunflowers, a 3 Sisters Grow Bag Garden offers a space-saving, eco-friendly way to produce fresh food. You’ll also carry on a time-honored gardening tradition adapted for modern container gardening. With some planning, regular watering via an olla, and some basic care, you can harvest delicious produce from your porch, patio, or backyard.