Bok choy Brassica rapa subsp. chinensis
Bok choy (Brassica rapa subsp. chinensis) is an annual vegetable in the Brassicaceae family. It grows 20–35 cm (8–14 in) tall and 20–30 cm (8–12 in) wide, wants part sun to part shade and high water, and is hardy to about -3 °C (27 °F). Space plants about 20 cm (8 in) apart.
Plan Bok choy in your garden →
Free. Draw your beds, then watch it grow through the year in 2D and 3D.
Bok choy at a glance
| Type | Annual vegetable |
|---|---|
| Family | Brassicaceae |
| Mature height | 20–35 cm (8–14 in) |
| Mature spread | 20–30 cm (8–12 in) |
| Spacing | 20 cm (8 in) centre to centre |
| Sun | Part sun to part shade, at least 4 h of direct sun a day |
| Water | High; drought tolerance none, waterlogging tolerance none |
| Cold hardiness | About -3 °C (27 °F) once established (roughly USDA zone 9) |
| Heat stress | Likely above about 26 °C (79 °F) |
| Flowering | about 6–9 weeks after planting, for 2–4 weeks |
| Days to maturity | About 50 days from planting |
| Wind tolerance | Low |
| Pollinator value | Low |
| Edible | Yes: leaves, stalks |
| Common in gardens of | 🇨🇳 China, 🇯🇵 Japan, 🇹🇭 Thailand, 🇸🇬 Singapore, 🇺🇸 United States, 🇦🇺 Australia, 🇻🇳 Vietnam |
Is Bok choy toxic?
- People: not known to be toxic
- Cats: not known to be toxic
- Dogs: not known to be toxic
Bok choy is non-toxic to people and pets.
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 Bok choy
Good neighbours
- good With Rhubarb: Traditional lore says rhubarb planted near brassicas helps against clubroot and pests; the evidence is weak and not confirmed by trials. Evidence D
- good With Nasturtium: Nasturtiums act as a trap crop for cabbage white butterflies and blackfly, drawing some pressure away from brassicas. Evidence C
Shared pests and diseases
- Clubroot: Clubroot spores persist in soil up to 20 years; keep brassicas in a rotation. Evidence B
Questions about Bok choy
- How far apart should I plant Bok choy?
- About 20 cm (8 in) apart, centre to centre. A mature plant spreads 20–30 cm (8–12 in).
- Does Bok choy need full sun?
- Part sun to part shade: at least 4 hours of direct sun a day.
- How much water does Bok choy need?
- High water. Drought tolerance is none and waterlogging tolerance none.
- How cold-hardy is Bok choy?
- It tolerates about -3 °C (27 °F) once established, roughly USDA zone 9. As an annual it is usually planted out after the last frost.
- When does Bok choy flower?
- About 6–9 weeks after planting, for 2–4 weeks.
- Is Bok choy poisonous to cats and dogs?
- For cats it is not known to be toxic; for dogs not known to be toxic; for people not known to be toxic. Bok choy is non-toxic to people and pets.
- What grows well with Bok choy?
- Traditional lore says rhubarb planted near brassicas helps against clubroot and pests; the evidence is weak and not confirmed by trials. Nasturtiums act as a trap crop for cabbage white butterflies and blackfly, drawing some pressure away from brassicas.
Sources and evidence
Evidence grade C (C: plausible, mixed evidence).
- ASPCA Toxic and Non-Toxic Plant List, ASPCA
- FAO Irrigation and Drainage Paper 56 — Crop Evapotranspiration, FAO
- RHS Plant Finder, Royal Horticultural Society
- University extension gardening guides (general), Various land-grant university extensions
Notes and assumptions
- Typical garden-cultivar values; varieties differ.
- Bolts in heat and long days.
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
- Broccoli Brassica oleracea var. italica
- Cauliflower Brassica oleracea var. botrytis
- Cabbage Brassica oleracea var. capitata
- Kale Brassica oleracea var. sabellica
- Radish Raphanus sativus
- Brussels sprout Brassica oleracea var. gemmifera
- Kohlrabi Brassica oleracea var. gongylodes
- Collard greens Brassica oleracea var. viridis