Chinese yam (nagaimo) Dioscorea polystachya
Chinese yam (nagaimo) (Dioscorea polystachya) is a deciduous perennial vegetable in the Dioscoreaceae family, native to China, Korea and Japan. It grows 2–4 m (6.6–13 ft) tall and 50 cm–1 m (20 in–3.3 ft) wide, wants full sun and moderate water, and is hardy to about -25 °C (-13 °F). Space plants about 40 cm (16 in) apart.
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Chinese yam (nagaimo) at a glance
| Type | Perennial vegetable, deciduous |
|---|---|
| Family | Dioscoreaceae |
| Mature height | 2–4 m (6.6–13 ft) |
| Mature spread | 50 cm–1 m (20 in–3.3 ft) |
| Spacing | 40 cm (16 in) centre to centre |
| Sun | Full sun, at least 5 h of direct sun a day |
| Water | Moderate; drought tolerance low, waterlogging tolerance none |
| Soil pH | 5.5–7 |
| Cold hardiness | About -25 °C (-13 °F) once established (roughly USDA zone 5) |
| Heat stress | Likely above about 34 °C (93 °F) |
| Flowering | from about July for 3–6 weeks (northern hemisphere; later in cold climates, earlier in warm ones) |
| Wind tolerance | Low |
| Pollinator value | Low |
| Edible | Yes: tubers (grated raw as tororo, or cooked), aerial bulbils |
| Native to | China, Korea and Japan |
| Common in gardens of | 🇨🇳 China, 🇯🇵 Japan, 🇰🇷 South Korea |
| Invasive in | eastern United States (spread by bulbils): check local rules before planting |
Is Chinese yam (nagaimo) toxic?
- People: mildly toxic
- Cats: mildly toxic
- Dogs: mildly toxic
- Parts: raw skin
Raw peel can itch (oxalate crystals); the flesh is eaten raw in Japan.
If a child or pet may have eaten part of a plant, call a poison centre or vet straight away.
Companion planting: what to grow with Chinese yam (nagaimo)
No well-documented helpful pairing. Group it with plants that like full sun and moderate water.
Questions about Chinese yam (nagaimo)
- How far apart should I plant Chinese yam (nagaimo)?
- About 40 cm (16 in) apart, centre to centre. A mature plant spreads 50 cm–1 m (20 in–3.3 ft).
- Does Chinese yam (nagaimo) need full sun?
- Full sun: at least 5 hours of direct sun a day.
- How much water does Chinese yam (nagaimo) need?
- Moderate water. Drought tolerance is low and waterlogging tolerance none.
- How cold-hardy is Chinese yam (nagaimo)?
- It tolerates about -25 °C (-13 °F) once established, roughly USDA zone 5.
- When does Chinese yam (nagaimo) flower?
- From about July for 3–6 weeks (northern hemisphere; later in cold climates, earlier in warm ones).
- Is Chinese yam (nagaimo) poisonous to cats and dogs?
- For cats it is mildly toxic; for dogs mildly toxic; for people mildly toxic. Raw peel can itch (oxalate crystals); the flesh is eaten raw in Japan.
- What grows well with Chinese yam (nagaimo)?
- There is no well-documented companion pairing for Chinese yam (nagaimo). Group it with plants that like the same sun (full sun) and water (moderate).
Sources and evidence
Evidence grade B (B: extension service or peer-reviewed).
Notes and assumptions
- Long straight tubers reach a metre deep; cinnamon-scented flowers. Bulbils make it invasive in parts of the US.
Reference values for planning, not horticultural, veterinary or medical advice. Varieties, soils and local climates differ: check with a local nursery or extension service.
Related plants
- White bat lily Tacca integrifolia
- White yam Dioscorea rotundata
- Tomato Solanum lycopersicum
- Cherry tomato Solanum lycopersicum var. cerasiforme
- Potato Solanum tuberosum
- Bell pepper Capsicum annuum
- Lettuce Lactuca sativa
- Carrot Daucus carota subsp. sativus