Oca
Oxalis tuberosa
Also known asNew Zealand yam (in NZ) · Uqa · Yam (regional misnomer) · Apilla
Environment
The bounded range this crop tolerates.
Climate and zones
- USDA zones
- 7–10 (winter low around -18°C)
- Frost
- frost sensitive (dies at first frost)
- Season
- cool (spring/fall)
Growing systems
Root mass: moderate.
Growing media
| Medium | pH effect | Retention | Bacterial surface |
|---|---|---|---|
| Soil-based mix (Potting soil) | varies | high | high |
Nutrient demand by stage
NPK ratios are relative weights. EC targets shift through the plant's life.
| Stage | N | P | K | EC (mS/cm) |
|---|---|---|---|---|
| seedling | 2 | 1 | 1 | 1 |
| vegetative | 2 | 1 | 2 | 1.4 |
Aquaponics suitability
Not recommended
Fish waste alone doesn't supply enough of what this crop demands. Grows in hybrid systems with supplemental dosing, but expect active management.
Care notes
A specialty tuber crop requiring specific conditions. Media beds or large containers (15 L) with loose substrate. EC 1.5-2.5 mS/cm. pH 5.5-6.5. Temperature: 12–20°C (cool highland climate; heat above 28°C suppresses tuber formation). Moderate light (DLI 12-18 mol/m2/day). The critical challenge at temperate latitudes: oca only forms tubers when day length drops below 12 hours (typically October-November in the northern hemisphere), but the plant needs to be large and established by then to produce worthwhile tubers. Start early (March-April) and grow through summer to build a large plant, then hope for a long enough frost-free autumn for tuber formation. In mild-winter areas (zones 8+), this works. In cold climates, frost kills the plant before tubers develop fully. Growing under artificial short-day conditions (covering plants to limit light hours starting in August) is an experimental workaround. Harvest after foliage dies back from frost, digging carefully. Cure tubers in sunlight for 1-2 weeks to sweeten them.