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When to Plant Kai Lan in Orange County, CA

Orange County, California Zone 10b May

Orange County, California gardeners: here's your May plan

May rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Orange County, California.

Avg. last frost February 13
Avg. first frost December 11
Soil temp (4") 79°F
Watering Critical
Pest pressure High
Daylight 13.7 hrs
  1. Basket week: kai lan

    This is the payoff month. Bring a basket, bring a friend, and get into the beds.

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Kai lan (Chinese broccoli) is a brassica grown for its thick, glossy stems and small flower buds. It has a slightly bitter, broccoli-like flavor essential in Cantonese cooking.

Orange County, California is in USDA Zone 10b. The average last spring frost is February 13 and the first fall frost is December 11, giving you a growing season of approximately 301 days.

At an elevation of 405 feet, Orange County receives approximately 13.8 inches of rainfall annually with predominantly loam soil. Summer highs average 88°F, providing good warmth for Kai Lan during the growing season. With low rainfall, drip irrigation is essential for growing Kai Lan successfully. Mulch heavily to conserve soil moisture.

Orange County, CA (Zone 10b) Year-round
301 days
Last Spring Frost February 13
301 growing days
First Fall Frost December 11

Orange County Soil Profile

Soil Type

Loam

Soil pH

5.7-7.6

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (223 days to spare)
Start indoors: Jan 5 Transplant: Feb 2 🍅 Harvest: Mar 23 – Apr 20
Recommended (50%) ✓ Fits season (224 days to spare)
Start indoors: Jan 16 Transplant: Feb 13 🍅 Harvest: Apr 3 – May 1
Safe Start (90%) ✓ Fits season (185 days to spare)
Start indoors: Mar 5 Transplant: Apr 2 🍅 Harvest: May 21 – Jun 18

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 Orange County

How your county's soil matches Kai Lan's growing requirements.

Soil pH

Your soil pH (5.7–7.6) overlaps with Kai Lan's range (6.0–7.5), though not a perfect match.

Soil Texture

The loam soil in Orange County is excellent for Kai Lan — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (2.1%). Annual compost additions will help Kai Lan.

How to Plant Kai Lan

0.5"
Planting Depth
6"
Between Plants
12"
Between Rows

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

Succession Planting Kai Lan

8
successive plantings in your 301-day season

Sow every 5.1 weeks. Last sowing by Oct 12 to harvest before frost.

For a dedicated fall crop, sow by Oct 16.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.2″/week
You supply
1.0″/week
Watering frequency 2-3 times/week
Season total 2,606 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Kai Lan

Kai Lan needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Kai Lan Needs Rainfall You Supplement Action
Jan 2.4" 0" ❄️ Dormant
Feb 4.3" 2.6" 1.7" 💧 Light watering
Mar 4.3" 2.2" 2.1" 💧 Light watering
Apr 4.3" 1.1" 3.2" 🚿 Regular watering
May 4.3" 0.4" 3.9" 🚿 Regular watering
Jun 4.3" 0.1" 4.2" 🚿 Regular watering
Jul 4.3" 0" 4.3" 🚿 Regular watering
Aug 4.3" 0" 4.3" 🚿 Regular watering
Sep 4.3" 0.2" 4.1" 🚿 Regular watering
Oct 4.3" 0.7" 3.6" 🚿 Regular watering
Nov 4.3" 1.5" 2.8" 🚿 Regular watering
Dec 4.3" 2.7" 1.6" 💧 Light watering

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

Kai Lan 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.

Kai Lan needs ~840 GDD — county provides 4,832 GDD Excellent fit

Kai Lan Planting Timeline — Orange County, CA

Kai Lan Planting Calendar

Activity When Date Range
Start Indoors January 16 Jan 16 – Jan 30
Transplant Outdoors February 13 Feb 13 – Feb 27
Direct Sow January 23 Jan 23 – Feb 13
Harvest April 3 Apr 3 – May 1
Fall Sowing October 16 Oct 16 – Oct 30

Plant 0.5" deep · 6" apart · Rows 12" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · 2-3 times/week

📅 Days to Maturity

45–60 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 10b

📆 Growing Season

301 days in Orange County

Growing Tips for Kai Lan in Orange County

Direct sow Kai Lan outdoors after February 13 in Orange County when soil has warmed and frost danger has passed.

Your generous 302.0-day season in Orange County allows multiple plantings of Kai Lan. Sow every 22.0 days for continuous harvest.

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

Orange County receives only 14" of rain annually. Kai Lan needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Direct sow in spring or fall. Harvest when flower buds first appear but before they open. Cut stems at the base to encourage side shoots. Prefers cool weather.

Companion Planting

Good Companions

Avoid Planting Near

  • Strawberries

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Kai Lan in Orange County, CA?

Orange County is in Zone 10b with an average last frost of February 13. Plan your Kai Lan planting based on this frost date — see the calendar above for exact timing.

What planting zone is Orange County, CA?

Orange County, California is in USDA Hardiness Zone 10b. The average last spring frost is February 13 and first fall frost is December 11.

🌱

Your Orange County Garden Planner — Free

A 24-page printable planner built for Orange 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 Orange 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.