The Three Sisters’ Garden: Corn, Bean & Squash

For the last few years I’ve been experimenting with a very traditional form of gardening in my bottom garden bed.

That system is, of course, the Three Sisters. You might have heard of it, and you might even have tried it. I’ve known many people (including me!) fail the first time they try it, and I think that’s largely down to failing to adapt the system to local climates and plant varieties.

Before we dive in, let’s take a look at how it works in its native land.

What is the Three Sisters’ Growing System?

The Three Sisters is a traditional way of growing crops together that comes from Indigenous farming in North America. Instead of neat rows, crops are grown together in small groups, usually in mounds.

At its simplest, you grow corn, beans and squash together. The corn goes in first and grows tall. The beans climb it instead of needing canes, and provide nitrogen to the corn and squash. The squash spreads out across the ground, shading the ground, preserving moisture and repressing weeds.

In practice, it was more of a loose system than a fixed recipe. Different communities did it differently depending on their climate and soil. Some added sunflowers around the edges. Others left in plants we’d probably pull out as weeds, but which were actually useful crops in their own right. It’s closer to a small, mixed planting than a tidy three-crop system.

The mounds are also doing more work than people realise. They help with drainage, they warm up faster in spring, and they concentrate fertility. There are also accounts of people burying fish under the corn. If you try it, you’ll need to bury it properly – otherwise something will dig it up.

There’s also a cultural layer to it. The name “Three Sisters” comes from storytelling traditions, where the plants are seen as sisters who grow best together. Corn is usually the tall, protective one, beans the climber, and squash the one that covers the ground. It wasn’t just a growing method – it was part of a wider way of growing and using food.

Two caveats

I’ve always loved the idea of the three sisters, but I do have two reservations, and one comes down to the nitrogen fixing properties of the beans.

The traditional idea is that the beans fix nitrogen from the air to feed the corn and the squash. However, when we plant green manure, we typically cut it down before it flowers or fruits, as the plant will otherwise use the nitrogen for itself. When you cut it down, the roots rot in the soil, adding nitrogen.

So I’m a little sceptical as to whether the beans actually feed the corn in real time. However, if you leave the roots of the beans when you cut them, any remaining nitrogen should stay in the soil.

Secondly, it doesn’t eliminate all weeds. I always have some left, and as the vegetation grows so densely, that usually means clearing everything out at the end of the year.

Caveats aside (and even without complete success), I love the system. The visuals are impressive, the maintenance is minimal and the harvest delicious.

My (Welsh) Three Sisters Version

Here’s how I’ve been growing three sisters

1. Plant the sweetcorn first in potting compost.
2. When the sweetcorn is about 6 inches high, transplant it into the garden. Remember that because corn is wind pollinated, it’s best planted in blocks.
3. Plant two bean seeds next to each sweetcorn. I plant two in case one fails. You could start these separately in compost, but they’re fairly reliable unless you have mice, rats or other bean-loving vermin around.
4. Mound soil and/or compost up around each sweetcorn as they and the beans grow. I’ve differed here from the original method. In the original 3 sisters method, several corn plants are grown in each mound, but I stick to one per position as I like to give them a bit more space. The original method could possibly be more suited to sweetcorn’s native environment? (Note I find the biggest challenge here is the birds, as they love scratching round in loose compost.)
5. Around the same time, I start the squash plant in compost in a propagator. When it’s large enough, I dig a hole, add some well-rotted manure, and plant it in. You don’t need the manure, but I’ve found that when you do this the squash grows massive. One year it grew 20 foot long, then invaded my neighbour’s garden and produced a squash in it. I gave her the option of me cutting it back or her taking the squash – she chose the squash.I put the squash plant some way off from the beans, and then let it grow into them, as the variety I use is a lot more vigorous than the ones traditionally used.
6. When the crops are finished, I cut all the plants at the base, compost the tops and allow the base to rot. I have experimented with covering the sweet corn stalks with compost and leaving them there as a mulch, but the stalks take a long time to break down this way.

I sometimes also plant a mass of wildflowers in the corner of the bed. These look great and create the glorious chaos I love in this part of the garden.

Two thirds successful – lessons learned

I first jumped into this in my usual state of enthusiasm with squash, runner beans and corn.

The corn and the squash performed brilliantly (in fact, they have every time), but the runner beans failed.

Having researched it after the failure (yeah, I know), I found that runner beans are not generally recommended. They’re often too vigorous, can overwhelm the corn, and in some cases even pull the stalks over. In my case, they just didn’t establish properly, which is unusual as I normally find them foolproof.

The next two years I planted dwarf borlotti beans, mainly because I had the seeds around. These did better in that they survived, but they didn’t really use the corn and the harvest wasn’t great.

That’s what made me realise the variety point matters more than it first appears. You need a bean that will climb, but not too aggressively, and that seems to suit the conditions you’re growing in.

This year I’m trying two different beans – climbing borlotti beans and Blue Lake French beans. Both are well suited to the UK, but if you’re considering the three sisters system, it’s well worth checking what works in your climate first. 

Related Posts

• 4 Productive Vegetables That Thrive Without Compost
• Carbon to Nitrogen Ratio: The Key to Fast, Healthy Compost
• How to Use Compost For Maximum Effect

Three Sisters in Arizona image by Spencer-Nägy licenced under creative commons.