Melon Sisters (small bed)
Cowpeas on a trellis with melons covering the ground, for a bed too small for corn.
Why these plants work together
Here is how these plants help each other, with how sure we are of each:
- Trellis provides vertical support
- Melon vines suppress weeds and retain soil moisture
- Cowpeas improve the ground for next season
Space it needs
At least 1.5 m²16 ft². If your bed is smaller, the planner grays this plant team out, says why, and offers the nearest adaptation that fits. It never swaps in something else without telling you.
Adapted from Melon Sisters.
What it looks like planted
- 3 × Cowpea
- 1 × Melon
Between seasons
Nothing is left living in the bed over winter; the whole planting is re-established.
What it claims
Melon vines suppress weeds and retain soil moisture
How it works: A living cover keeps a leaf canopy over the ground. It intercepts light at the soil surface, so weed seedlings are shaded out before they establish, and it slows surface evaporation, so the soil holds more water. In a Three Sisters planting this is the squash's role. Its broad leaves shade the bed.
Evidence: checked against 2 sources in the research-based literature.
The 2 sources
Mulching for soil and garden health UMN Extension
Studies show that mulch reduces evaporation from the soil surface and helps soil hold water.
Creating a Three Sisters Garden Cornell Cooperative Extension (Warren Co. Master Gardener)
The large, prickly squash leaves shade the soil, preventing weed growth
Cowpeas improve the ground for next season
How it works: A legume fixes atmospheric nitrogen into its tissue as it grows. When the crop is killed and its residue decomposes, soil microbes mineralize that organic nitrogen, converting a form plants can't use into one they can, and release it for the next crop. How much depends on how well the legume grew, and it is lower on sandy soils.
Evidence: checked against 2 sources in the research-based literature.
The 2 sources
Growing Cover Crops for Nitrogen on Vegetable Farms Penn State Extension
When cover crops are killed and begin to decompose, nitrogen can be released from the residues back into the soil where it can feed the next crop
Late Summer Planting Legumes to Produce Nitrogen Credits for Next Year Univ. of Wisconsin-Madison Extension (Crops & Soils)
The nitrogen credit depends on the amount of crop growth and when the legume was planted. Nitrogen credits are 50 lb N/a lower on sandy, coarse-textured soils.
What to keep in mind
Label as an adaptation, not as Melon Sisters. The cowpeas climb the trellis instead of corn, so the corn block is gone, along with the pollination mechanism that needs it. The melon stays the ground layer; on a bed this small, let its vines run over the edges so they don't crowd the roots.
Who does what, and the swaps
Each job in this planting can be done by more than one plant. The usual choice comes first, and each swap says what it costs.
Support
- Or a structure: Cattle panel
- What that swap costs: No biomass, no romance. About $20. Reusable across seasons.
- Swaps: Sunflower
- What a swap costs: A heavy nitrogen feeder that competes with the cowpeas. It needs a ~30-day head start or the vines pull it down, and it holds up about 2 vines per stalk.
Fixer
- Usual choice: Cowpea
- Swaps: Pole lima, Yardlong bean
Cover
- Usual choice: Melon
- Swaps: Watermelon
What it costs the ground
Rotation history belongs to the ground itself, so this is what the planner records about this patch after the plant team comes out.
- Legumes: counts as a full season of this family
- Cucurbits: counts as a full season of this family