How to use the Three Sisters Cultivation Method

The cultivation method known as Three Sisters has an interesting history. You can read about it in one of Plews’ earlier blogs (link below) Here, I’d like to focus on how to use it as a way to grow particular crops in your garden – you could call it an easy maintenance system and I feel it should be more widely known.

What are the Three Sisters?

Traditionally it combines squash, beans and maize and was a common cultivation method used by both the North and South American Indians.

It is sometimes referred to as an inter-cropping or inter-planting method of cultivation. It is beneficial to the plants as follows: –

The Maize grows tall and provides a support for the climbing bean. Both these plants provide shade from the noon sun for the squash.
Maize is a nitrogen hungry crop. Beans are leguminous plants, able to ‘fix nitrogen’, accessing atmospheric nitrogen and making it available in the soil to the other plants.
The squash with its large leaves keeps the soil moist and reduces competition from weeds.

This is a companion planting system rather than a monoculture. The three sisters together improve the condition of the soil by increasing beneficial mycorrhiza which in turn encourage a symbiotic relationship between the plants’ roots and the surrounding soil.

As a cultivation method it is not perhaps very well known, but is worth a closer look. It would be attractive in the ornamental kitchen garden and can be used both in the open ground and in a raised bed.

Benefits as a Growing Method

This growing method utilises some of the properties of each of the individual plants so that they all benefit. Often described as an intercropping method of cultivation, the plants form more of a symbiotic relationship than most intercropped edible plants. It could be called a companion planting system in the true sense, as the crops work so well together.

The nitrogen seeped into the soil by the beans benefits the soil and the following year’s crops. By growing them together, some of the reasons for following a system of crop rotation are no longer relevant. This makes it possible to grow the same crops for a number of years in the same place without there being a detrimental effect on either the soil or plant health.

These benefits also contribute to an easier maintenance regime. Evidence (largely empirical) suggests that there are fewer issues with pests and diseases. And it is a method well-suited to organic and vegan gardening styles. Plus, when grown together, the three sisters crops produce up to 20% more protein and carbohydrates than they would if grown as three separate monocultures.

Method of Cultivation

The Three Sisters is sometimes referred to as a ‘stacked’ or ‘layered ‘ cultivation method, and it encompasses companion planting and inter-cropping.

For smaller areas use compact squash varieties; both winter and summer squash are suitable.
You may want to start the beans with short stakes to get them started on their upward journey, although if they’re planted close to the maize its not really needed.
The beans can be climbing beans or runner beans – they just need to be able to scramble.
It’s best to have taller maize varieties as they need to stand slightly ‘proud’ to ensure wind pollination.
As for starting off the beans, squash and corn, follow your preferred method for indoor propagation.
Planting out should be in two stages, firstly the maize, then the beans and squash together. This allows the maize to get some height.

Three Sisters – Laying out / Planting patterns

How you lay out the Three Sisters plants in your garden will depend on how much space you have and what shape it is. I suggest two simple patterns below, both of which I have used and which are able to be repeated if you have a larger space.

The first is more usually for a square space. Plant maize in a block in the middle, climbing beans around them and squash around the outside, at the corners. For an 8 foot square try 9 x maize, 6 x beans, 4 x squash.

Another pattern which is to have three rows, each marked off into 5 stations. Rows one and three have maize and beans at stations 2 and 4; row two has maize and beans at station 1,3 and 5. For 10 foot rows have 4 x maize and 4 x bean plant sat each station; 1 x squash; you will need at least three rows, roughly 2 foot apart.

Some of the spacing above depends on which varieties are used (size).

There are some difference in the sunlight requirements of the three different crops. However, they will all be happy in a spot which gets direct sunlight for 4- 6 hours and light for most of the rest of the day. In other words, hot sunlight all day is too much; shade for most of the day is not enough.

Harvesting of beans and squash occurs as they mature during the season. Maize will have a shorter window of readiness. If there are still beans and squash to ripen after the maize has been harvested, leave the stalks as support.

Three Sisters – or More Sisters?

This growing method is already a companion planting system, and there’s every reason for why adding more ‘sisters’ is a positive move. By more sisters I am referring to flowering plants to: –

encourage pollinators
deter pests
act as sacrificial plants
add to the ornamental look of your vegetable patch
be complementary culinary herbs

As both beans and squash are insect pollinated it makes sense to encourage pollinators in to be sure that pollination occurs. Interestingly, the bean flowers themselves attract predators who will eat some of the maize pests.

Sacrificial plants are those which you hope will be eaten by the slugs and snails so they don’t chomp on your vegetables. It doesn’t always work in isolation, but is more successful when used in collaboration with other organic pest repellent methods.

There are a wealth of suitable flowering plants which will perform more than one of these duties. For example Nasturtiums, Calendula, Cleome, Limnanthes (poached egg plant), Nepeta, Thyme, Rosemary, Summer Savory, Chives. Plant the companion flowers as a decorative edge or spread throughout – whichever best suits the ‘look’ you wish to achieve.

And the next steps are…

Are you wondering if the Three Sisters would work in your vegetable plot or kitchen garden? There are a few questions to ask yourself.

Firstly, do you like eating the three vegetables? (a bit critical this one!)

Do you operate a strict crop rotation? This system can be incorporated, but that requires some careful planning – or a Plews Gardening Lesson to help work it all out on your own plot.

What is your soil like? Preparing the soil for your vegetables and fruit growing is crucial, they have to put on a lot of growth and produce crops in a short space of time so nutritious soil is a must. (see blog link below for more)

Remember if you plan it as you would plan any of your edible gardening then you should be successful. Even when the weather is against you and the harvest isn’t as bountiful as you’d hoped…there’s always next year!