Bok Choy
Brassica rapa subsp. chinensis
Brassicaceae · cabbage family
- Matures
- 30–45 days
- Harvest
- Once · Annual
- Sun
- 4–8 hrs
- Spacing
- 6–8 in
Planting window
When to sow, by microclimate — foggier blocks run a different calendar than sunnier ones.
| Jan | Feb | Mar | Apr | May | Jun | |
|---|---|---|---|---|---|---|
| Foggy | ● | ● | ● | ◐ | ◐ | ◐ |
| Sunny | ● | ● | ● | ● |
| Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|
| Foggy | ● | ● | ● | ◐ | ||
| Sunny | ◐ | ● | ● |
Well-suitedMarginalNot suited
Sunlight
How well it does at each level of direct sun per day.
<2 hrsNot suited
2–4 hrsMarginal
4–6 hrsWell-suited
6–8 hrsWell-suited
8+ hrsMarginal
Well-suitedMarginalNot suited
Soil depth
Root room it needs — useful for sizing raised beds and containers.
6–10"Well-suited
10–15"Well-suited
15–18"Well-suited
18–24"Well-suited
Well-suitedMarginalNot suited
Spacing
Room each plant needs — along the row and between rows — for sizing beds.
- In-row
- 6–8 in
- Between rows
- 12–24 in
Growth habit
The shape it makes in the bed and how tall it gets — what tells you whether to give it a trellis, a stake, or just room.
- Habit
- Low mound
- Mature height
- 6–12 in
Low and self-supporting — no staking needed.
How to start it
Sow it where it grows, or raise it under cover and set it out — and how far ahead to start the seedlings if it's the latter.
- Usually
- Direct-sow
- Start indoors
- 3 weeks ahead
Direct-sowWell-suited
TransplantWell-suited
Sown straight into the bed it will grow in.
Well-suitedMarginalNot suited
Getting started
How it goes in the ground — how deep to sow or set it, and the soil temperature it needs to wake up. The cold-soil floor is the real limiter for direct-sowing in a foggy SF spring.
- Started from
- From seed
- Ideal soil temp
- 50–80°F
- Sow depth
- 0.25–0.5 in
- Time to emerge
- 4–7 days
Germinates between 50–80°F; happiest around 50–80°F.
30°F110°F
IdealWorkable
Pests & diseases
What tends to trouble this crop — what it is, what you'll see, and what to do about it, least-toxic first.
Shares the leafy cole-crop pest complex — see kale, broccoli, and cabbage.
Pests3
Aphids
- What it is
- Aphids have soft pear-shaped bodies with long legs and antennae and may be green, yellow, brown, red, or black depending on the species and the plants they feed on. A few species appear waxy or woolly due to the secretion of a waxy white or gray substance over their body surface.
- What you'll see
- Low to moderate numbers of leaf-feeding aphids aren't usually damaging in gardens or on trees. However, large populations can turn leaves yellow and stunt shoots; aphids can also produce large quantities of a sticky exudate known as honeydew, which often turns black with the growth of a sooty mold fungus.
- What to do
- Before planting vegetables, check surrounding areas for sources of aphids and remove these sources. On the other hand, these aphid-infested weeds can sometimes provide an early source of aphid natural enemies.
Cabbage Worms and Loopers
- What you'll see
- Worms and loopers are light to dark green. Adult loopers are gray or brown moths while cabbage worms are white butterflies. Worms and loopers chew holes in leaves and hide in kale heads.
- What to do
- Control worms and loopers with appropriate insecticides or biological measures.
Flea Beetles
- What it is
- Their small size, enlarged back legs, characteristic shot-hole damage, and habit of jumping when disturbed make flea beetles easy to identify. There are numerous flea beetle species.
- What you'll see
- Adults feed mostly on leaves, leaving tiny pits or small holes at their feeding sites. Flea beetles feeding together can cover leaves with bleached, pitted areas or ragged holes.
- What to do
- Remove debris in the fall to remove any overwintering beetles. Reflective mulches applied very soon after planting and before plants become infected can be helpful.
Sources
Every figure above is backed by these.
- UC Master Gardeners, San Mateo–SF Countiesbacks plantingWindow · Foggy & Sunny calendars, Mustard row used as the mustard-family proxy for bok choy (Brassica rapa; SF calendar has no bok choy row): seed foggy Jan-Oct, sunny Jan-Apr & Aug-Sep. Provides the Foggy/Sunny split.
- Golden Gate Gardening (Pam Peirce)backs plantingWindow, sunlight, lifecycle, harvestStyle · Foggier/Sunnier planting-times charts, Mustard row (mustard-family proxy): used to soften the SF-calibrated summer edges to maybe (foggy Apr-Jun, sunny Jul). Also backs sunlight: bok choy is a cool-season leafy brassica that tolerates part shade and bolts in heat, so full sun in sunnier spots is only marginal (8+ hrs = maybe). Habit and harvest: annual, once — from this source's entry for this crop.
- UC Master Gardeners, Santa Clara Countybacks plantingWindow, daysToMaturity, inRowSpacing · UC MG Santa Clara bok choy page: 'Direct seed or transplant 6 to 8 inches apart in February to April ... or September to October' (spacing 6-8; corroborates the Feb-Apr / Sep-Oct Bay Area window); 'Harvest about a month after sowing' (days floor ~30, fast/baby).
- UC Master Gardeners, Sonoma County (Planting Summary)backs daysToMaturity, rowSpacing, startMethod · Vegetable Planting Summary, 'Greens, assorted' row (notes name Asian greens explicitly; bok choy is an Asian green): 35-45 days. With the Santa Clara ~1-month figure this gives the 30-45 day range. Between-row spacing 12-24 in (Greens, assorted row). Start method: Vegetable Planting Summary, Cabbage, Chinese row: method D (usually direct-sown).
- UC Master Gardeners, Santa Clara County (Containers)backs soilDepth · No bok choy row; assigned shallow-rooted (6-9 in) by parity with the quick leafy greens listed under shallow-rooted (lettuces, spinach), which bok choy resembles in rooting.
- Cornell University Home Gardeningbacks germination · Cornell pak choy/bok choy: germination 50–80°F; emergence 4–7 days
- USDA GRIN Taxonomybacks botany
- University of Minnesota Extensionbacks plantingDepth, growthHabit · UMN Extension: 'Plant seed shallowly, one-fourth to one-half inch deep.' Height/habit: 'For dwarf varieties, this may be only six inches tall. Full-sized varieties can be a foot tall.' (6-12 in) - a low, compact leafy rosette (low-mound).
- UC Master Gardeners, Santa Clara Countybacks startMethod · Start method: Planting chart: Bok choy carries both a Transplant row (3 weeks) and a Direct seed row.