Skip to content
Permagora
All guides

In the pathway: Getting started in permaculture

The Three Sisters

Maize, bean, squash: three plants that help one another on the same mound.

Level: Beginner 1 season (April to October)
A drawing of the Three Sisters: a maize plant serves as a stake for the climbing bean (mauve flowers), and the squash carpets the ground with its pumpkins.
Drawing: Garlan Miles · CC BY-SA 4.0 · source
Watch the videoLa méthode Milpa (maïs, courge, haricot)Zeprofdortie : PERMACULTURE

The guild's plates

Introduction

The milpa, or 'Three Sisters', is an age-old association developed by the peoples of Mesoamerica. It is a perfect illustration of the permaculture principle of beneficial associations: three crops complement each other in time and space to produce more from the same area, with less watering and weeding.

Background

The maize acts as a living stake, the climbing bean fixes atmospheric nitrogen through its root nodules, and the squash covers the ground with its wide leaves, keeping moisture in and smothering weeds. This trio forms a small ecosystem on a single mound.

Who this guide is for

Beginner or experienced gardeners with a sunny vegetable patch of at least 1.5 m². Suited to almost all of mainland France.

Why it matters

Soil explored more fully (maize forages nearer the surface, the bean more evenly down the profile, Zhang et al., 2014), water savings (the squash covers the ground and greatly reduces evaporation), space savings (3 harvests on the same area), resilience (in a heatwave, the squash protects the soil).

What to understand before starting

  • A full-sun spot, sheltered from strong winds.
  • Loose soil, worked to 30 cm, enriched with mature compost.
  • Soil temperature > 15 °C (generally after mid-May in northern France).
  • Suitable varieties: a tall-stemmed maize harvested ripe for grain (flour, polenta), not F1 hybrid (a sweetcorn, picked immature, is far less nourishing); climbing bean (not dwarf); trailing squash (red kuri, butternut).

Detailed steps

  1. Step 1

    Prepare the mound

    Form a mound 80 cm to 1 m wide, 15 to 20 cm high. Work in 1 to 2 buckets of mature compost per square metre. The domed shape drains excess water and warms the soil.

  2. Step 2

    Sow the maize

    In the centre, sow 4 to 6 maize kernels in a staggered pattern, 25 cm apart, 3 cm deep. Water. Grouped sowing ensures good cross-pollination (maize is wind-pollinated).

  3. Step 3

    Wait for emergence

    Be patient for 2 to 3 weeks, until the maize plants reach 15 to 20 cm tall. Without this, the bean will get the upper hand and smother the maize.

  4. Step 4

    Sow the bean

    At the foot of each maize plant, sow 2 to 3 climbing-bean seeds 3 cm deep. The maize will act as a natural stake.

  5. Step 5

    Sow the squash around the edge

    All around the mound, sow 2 or 3 squash seeds at least 80 cm apart. A single trailing squash can cover 4 to 6 m². Limit to 1 plant per mound.

  6. Step 6

    Mulch generously

    As soon as they emerge, cover the bare soil with 5 to 10 cm of straw, hay or dry clippings. This limits evaporation and feeds the soil.

  7. Step 7

    Tend and harvest

    Water regularly the first month, then cut back. Pick the green beans through the summer, sweetcorn when the silks turn brown, grain maize at full maturity, the squash after the first light frosts.

Concrete examples

  • Northern variant: 'Golden Bantam' sweetcorn (eaten fresh on the cob), 'Borlotti' bean (Phaseolus), 'Red Kuri' squash.
  • Southern variant: 'Bloody Butcher' maize, runner bean, 'Waltham Butternut' squash.
  • In a 1.2 m × 1.2 m square: 4 maize in the centre, 4 beans, 1 squash in a corner.

Common mistakes to avoid

  • Sowing bean and maize at the same time: the bean climbs too fast and breaks the young maize.
  • Choosing a dwarf bean instead of a climbing one: it won't use the living stake.
  • Putting several trailing squash on the same mound: they smother each other and everything else.
  • Adding too much nitrogen (fresh manure): the maize lodges, the bean makes lots of leaves and few pods.
  • Forgetting to mulch: the soil crusts, water runs off, the squash suffers.

Tips & best practices

Frequently asked questions

Can I grow the Three Sisters in a pot?
Hard: the squash needs a lot of room. For a balcony, swap the squash for a climbing nasturtium, keeping the maize and the climbing bean.
Do I need to water?
Yes the first month, then only during very dry spells. The mulch and the squash do the work.
What about slugs on the young squash?
Mulch with a ring of ash or coffee grounds around the seedlings for the first few weeks.

Key takeaways

  • The maize is a stake, the bean fixes nitrogen, the squash protects the soil.
  • Stagger the sowings: maize first, bean when the maize is 15 cm.
  • Mulch thick, space the squash, choose non-F1 varieties.

Sources

  • Mt. Pleasant, J. (2006). The science behind the Three Sisters mound system: an agronomic assessment of an indigenous agricultural system in the northeast. In Staller, J.E., Tykot, R.H. & Benz, B.F. (dir.), Histories of Maize (p. 529-537). Academic Press.
  • Mt. Pleasant, J. (2016). Food yields and nutrient analyses of the Three Sisters: a Haudenosaunee cropping system. Ethnobiology Letters, 7(1).
  • Zhang, C., Postma, J.A., York, L.M. & Lynch, J.P. (2014). Root foraging elicits niche complementarity-dependent yield advantage in the ancient 'three sisters' (maize/bean/squash) polyculture. Annals of Botany, 114(8), 1719-1733.
Back to all guides