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When to Plant Bok Choy in San Francisco County, CA

San Francisco County, California Zone 10b May

This month in San Francisco County, California

Each item below is timed to San Francisco County, California's frost dates and soil temperatures. Skip nothing, stress about nothing.

Avg. last frost February 23
Avg. first frost November 27
Soil temp (4") 78°F
Watering Critical
Pest pressure High
Daylight 14 hrs
  1. Basket week: bok choy

    Don't tug. Use scissors or pruners for clean cuts — torn stems invite disease.

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Bok choy is a Chinese cabbage variety with crisp white stalks and dark green leaves. It is a fast-growing cool-season crop ideal for stir-fries and soups.

San Francisco County, California is in USDA Zone 10b. The average last spring frost is February 23 and the first fall frost is November 27, giving you a growing season of approximately 277 days.

At an elevation of 412 feet, San Francisco County receives approximately 13.5 inches of rainfall annually with predominantly loam soil. Summer highs average 86°F, providing good warmth for Bok Choy during the growing season. With low rainfall, drip irrigation is essential for growing Bok Choy successfully. Mulch heavily to conserve soil moisture.

San Francisco County, CA (Zone 10b) Year-round
277 days
Last Spring Frost February 23
277 growing days
First Fall Frost November 27
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San Francisco County Soil Profile

Soil Type

Loam

Soil pH

6.2-7.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (216 days to spare)
Start indoors: Jan 5 Transplant: Feb 2 🍅 Harvest: Mar 16 – Apr 20
Recommended (50%) ✓ Fits season (200 days to spare)
Start indoors: Jan 26 Transplant: Feb 23 🍅 Harvest: Apr 6 – May 11
Safe Start (90%) ✓ Fits season (182 days to spare)
Start indoors: Mar 9 Transplant: Apr 6 🍅 Harvest: May 18 – Jun 22

Percentages indicate frost risk at transplant. The 70% safe window means there is a 30% chance of frost after transplant — suitable for cold-hardy crops or gardeners with frost protection. The 90% safe window is best for tender plants.

Soil Compatibility in San Francisco County

How your county's soil matches Bok Choy's growing requirements.

Soil pH

Your soil pH (6.2–7.2) is within Bok Choy's preferred range (6.0–7.5).

Soil Texture

The loam soil in San Francisco County is excellent for Bok Choy — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (3.0%). Annual compost additions will help Bok Choy.

How to Plant Bok Choy

1"
Planting Depth
15"
Between Plants
24"
Between Rows

Fall planting: Sow 8 weeks before your first frost date for a fall harvest.

Succession Planting Bok Choy

8
successive plantings in your 277-day season

Sow every 4.6 weeks. Last sowing by Sep 28 to harvest before frost.

For a dedicated fall crop, sow by Oct 02.

Plant Water Budget

Plant needs
0.7″/week
Rainfall provides
0.2″/week
You supply
0.6″/week
Watering frequency 1-2 times/week
Season total 1,473 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Bok Choy

Bok Choy needs approximately 0.7 inches of water per week (3" per month). Here's how your county's rainfall compares month by month.

Month Bok Choy Needs Rainfall You Supplement Action
Jan 2.3" 0" ❄️ Dormant
Feb 3" 3.1" 0" ✅ Rainfall sufficient
Mar 3" 2.2" 0.8" 💧 Light watering
Apr 3" 1.2" 1.8" 🚿 Regular watering
May 3" 0.3" 2.7" 🚿 Regular watering
Jun 3" 0.1" 2.9" 🚿 Regular watering
Jul 3" 0" 3" 🚿 Regular watering
Aug 3" 0" 3" 🚿 Regular watering
Sep 3" 0.1" 2.9" 🚿 Regular watering
Oct 3" 0.6" 2.4" 🚿 Regular watering
Nov 3" 1.4" 1.6" 🚿 Regular watering
Dec 2.1" 0" ❄️ Dormant

Water needs are for active growing months only (Feb–Nov in San Francisco County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Bok Choy Heat Requirements (GDD)

What are Growing Degree Days (GDD)?

Growing Degree Days measure the total warmth your plants receive during the growing season. Think of it as a "heat bank" — every day above 50°F deposits warmth that helps your plants grow.

Each plant needs a certain amount of accumulated heat to mature. If your county provides more GDD than the plant needs, it's a great fit. If it's close, you may want to choose faster-maturing varieties or start seeds indoors to get a head start.

Bok Choy needs ~725 GDD — county provides 4,031 GDD Excellent fit

Bok Choy Planting Timeline — San Francisco County, CA

Bok Choy Planting Calendar

Activity When Date Range
Start Indoors January 26 Jan 26 – Feb 9
Transplant Outdoors February 23 Feb 23 – Mar 9
Direct Sow February 2 Feb 2 – Feb 23
Harvest April 6 Apr 6 – May 11
Fall Sowing October 2 Oct 2 – Oct 16

Plant 1" deep · 15" apart · Rows 24" apart

Month-by-Month Timeline

MonthActivities
January Start Indoors
February Start Indoors Transplant Outdoors Direct Sow
March Transplant Outdoors
April Harvest
May Harvest
June
July
August
September
October Fall Sowing
November
December
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Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

0.7"/week · 1-2 times/week

📅 Days to Maturity

40–60 days

🧪 Soil pH

Needs 6–7.5 · Your soil: ideal

🗺️ USDA Zone

Zone 10b

📆 Growing Season

277 days in San Francisco County

Growing Tips for Bok Choy in San Francisco County

Direct sow Bok Choy outdoors after February 23 in San Francisco County when soil has warmed and frost danger has passed.

Your generous 278.0-day season in San Francisco County allows multiple plantings of Bok Choy. Sow every 20.0 days for continuous harvest.

Common pests for Bok Choy in this region include cabbage worm and flea beetles. Use row covers early in the season and inspect plants weekly.

General growing tips

Direct sow in spring or fall for best results. Keep soil consistently moist. Harvest whole heads or cut outer leaves for a cut-and-come-again approach.

Companion Planting

Good Companions

Avoid Planting Near

  • Strawberries

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Bok Choy in San Francisco County, CA?

San Francisco County is in Zone 10b with an average last frost of February 23. Plan your Bok Choy planting based on this frost date — see the calendar above for exact timing.

What planting zone is San Francisco County, CA?

San Francisco County, California is in USDA Hardiness Zone 10b. The average last spring frost is February 23 and first fall frost is November 27.

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Your San Francisco County Garden Planner — Free

A 24-page printable planner built for San Francisco County (Zone 10b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

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Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for San Francisco County, CA. Local conditions may vary. Last updated: May 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.