Three Sisters
Corn, beans and squash grown together — the one traditional polyculture with measured evidence that it out-produces the same area grown separately.
The plan
Each square is one square foot; the number is how many plants go in it at recommended spacing. North is the top of the plan — the tallest crops sit there so they don't shade the rest.
No recorded bad pairings between neighbouring squares in this plan.
Why it's arranged this way
Corn provides the pole, beans climb it, and squash covers the ground to hold moisture and suppress weeds. Studies find a land-equivalent ratio above 1, meaning the polyculture genuinely beats three separate monocultures. The measured driver is complementary root foraging and physical structure — not, despite the folklore, beans feeding nitrogen to the corn during the season.
- Sequence matters: sow corn first and let it reach about 6 inches before sowing beans, or the beans will pull down seedlings too weak to carry them.
- Corn is wind-pollinated and needs a block rather than a row — a 4×4 is the practical minimum for decent ear fill.
- The nitrogen story is wrong even though the practice is right. Same-season nitrogen transfer from legumes to neighbours is typically under 1%; the benefit arrives when the residue breaks down, so dig the bean plants in at the end rather than pulling them out.
What's in it, and when to plant
| Crop | Squares | Plants | Start indoors | Plant outside |
|---|---|---|---|---|
| Sweet corn | 6 | 6 | — | Apr 10 – Apr 23 |
| Pole bean | 4 | 32 | — | Apr 10 – Apr 23 |
| Summer squash / zucchini | 6 | 6 | — | Apr 17 – Apr 30 |
What you'll need
Bill of materialsSoil and equipment
- Raised bed soil, 12 in deep 16 cu ft · 11 bags · 0.593 cu yd
- Soaker hose — these crops split or bolt with uneven water
- Bird or insect netting
- Trellis or netting for climbing crops
- Straw or leaf mulch
- Floating row cover
Seed for this bed
- Sweet corn seeds 6 plants · 6 sq
- Pole bean seeds 32 plants · 4 sq
- Summer squash / zucchini seeds 6 plants · 6 sq
Soil volume is calculated from this bed's footprint at 12 inches deep — adjust it on the soil calculator. Plant counts come from square-foot density for each crop. As an Amazon Associate we earn from qualifying purchases. Equipment is listed because the crops in this plan need it, not because it is sponsored.
Other layout plans
The Beginner 4×8 Bed
The standard first raised bed: eight crops that are hard to kill, spaced properly, with nothing planted next to something it fights with.
4 × 4 ftThe Cut-and-Come-Again Salad Bed
A 4×4 bed of fast greens and roots that you harvest continuously rather than all at once. Ready in six weeks, productive for months.
6 × 4 ftThe Salsa Bed
Everything for a bowl of salsa in one 4×6 bed: tomatoes, peppers, onions and cilantro, timed so they are ready together.
6 × 4 ftThe Insectary Strip
A 4×6 border of flowering plants chosen for the evidence behind them — sweet alyssum for hoverflies, borage for pollination, calendula and dill for predatory wasps.
4 × 4 ftThe Partial Shade Bed
For the bed that only gets three to five hours of sun. Leafy crops and roots that genuinely prefer it, rather than fruiting crops that will merely survive.