Photo: James St. John — CC BY 2.0 · source
Survives zone 3 through 9
Starchy tubers cooked (boiled, roasted, fried) — a nutty, potato-like staple with roughly three times potato's protein; young pods, shoots and flowers also edible cooked. Tubers best harvested autumn to spring after 2+ seasons; borne like beads strung along the rhizome.
- Hardiness
- Zone 3 to 9
- Habit
- Vine
- Edible part
- Root, Shoot, Flower, Nut, Fruit
- Ripens
- Autumn
- Mature size
- Twining perennial vine 1–6 m; ⚠ spreads into colonies via rhizome — contain it
- Light
- Full sun to partial
- Soil pH
- 6.0–7.5 (nitrogen-fixing; tolerates poor soil)
- Environment
- Wetland
- Status
- Both wild and cultivated
- Years to fruit
- 3–5 yrs
- Pollination
- Insect-pollinated; many clones set seed poorly, but the crop is the tuber, not the seed
Growing guide
Fertilizing. Nitrogen-fixing legume that needs little supplemental feeding; a light, balanced feed in spring and again in summer is sufficient, since excess nitrogen favors vine growth over tuber production.
How it spreads. Spreads by a chain of enlarging tubers along its underground roots as well as by twining stems above ground; established plantings can spread indefinitely and are difficult to fully remove, so give it a dedicated, contained bed.
Growing tips. Needs a trellis, fence, or shrub to climb, and dislikes windy sites. Tubers take two to three years to reach a worthwhile size, and the best yields come from leaving a planting undisturbed for at least two growing seasons.