groundnut

Photo: James St. John — CC BY 2.0 · source

Survives zone 3 through 9

Harvest calendar

Best planted in early spring after your last frost, or in fall before the ground freezes, depending on your climate.

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 3–9

Habit

Vine

Edible part

Root, Shoot, Flower, Seed, 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

Native range

Eastern North America, from Ontario and Quebec south to Florida and Texas — damp thickets, riverbanks and the margins of wet woodland. A staple food of many Indigenous nations, and credited with keeping the Pilgrims alive through their first winters.

Status

Both wild and cultivated

Years to fruit

3–5 yrs

Growth speed

Fast — 1–2 m of twining stem in a season once the tubers are established

Spacing

45 cm (18 in) apart — about 4.9 per m² (4.6 per 10 sq ft)

Leaf shape

Alternate and pinnate with five to seven ovate, pointed leaflets on a twining stem — a bean's leaf, which is what it is.

Root system

A string of tubers strung along underground rhizomes like beads on a necklace, usually 20–60 cm down, joined by wiry runners — a colony rather than a single crown. Nitrogen-fixing root nodules come with it. That running habit is exactly why the record warns about containment.

Fruit description

Not the crop, though the pods are edible: narrow bean pods 5–12 cm, cooked like a green bean when young, and the ripe seeds cooked like a lentil. Many clones are triploid and set no pods at all. The tuber is what you grow it for — 2–5 cm, brown-skinned and white-fleshed, with roughly three times the protein of a potato.

Propagation

Plant tubers in spring, exactly as for potatoes; the small tubers along a runner are all viable. Seed is possible where a clone sets it but is slow and variable.

Pollination

Insect-pollinated; many clones set seed poorly, but the crop is the tuber, not the seed

The edible parts listed above are a starting point, not a field guide. Identify a plant with certainty — ideally against a local authority — before eating any part of it, and read the full disclaimer. Spotted something wrong? Report it.