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When to Plant Napa Cabbage in Sierra County, CA

Sierra County, California Zone 6b May

May in the garden — Sierra County, California

We've pulled the most time-sensitive tasks for Sierra County, California this May and put them front and centre. Tackle them in order.

Avg. last frost May 10
Avg. first frost October 22
Soil temp (4") 62°F
Watering Critical
Pest pressure Low
Daylight 14.2 hrs
  1. Time to transplant napa cabbage

    Water the tray well an hour before you transplant. Roots slide out cleanly and settle in faster.

Looking ahead to June
  • Starting indoors: napa cabbage

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Napa cabbage forms tall, barrel-shaped heads with tender, crinkled leaves and a mild, slightly sweet flavor. It is the primary cabbage used for kimchi.

Sierra County, California is in USDA Zone 6b. The average last spring frost is May 10 and the first fall frost is October 22, giving you a growing season of approximately 165 days.

At an elevation of 1,560 feet, Sierra County receives approximately 40.5 inches of rainfall annually with predominantly loam soil. Summer highs average 80°F, so choose short-season varieties of Napa Cabbage to ensure they mature before fall.

Sierra County, CA (Zone 6b) Moderate season
165 days
Last Spring Frost May 10
165 growing days
First Fall Frost October 22

Sierra County Soil Profile

Soil Type

Loam

Soil pH

6.7-7.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (73 days to spare)
Start indoors: Mar 21 Transplant: Apr 25 🍅 Harvest: Jun 20 – Jul 25
Recommended (50%) ✓ Fits season (74 days to spare)
Start indoors: Apr 5 Transplant: May 10 🍅 Harvest: Jul 5 – Aug 9
Safe Start (90%) ✓ Fits season (82 days to spare)
Start indoors: May 1 Transplant: Jun 5 🍅 Harvest: Jul 31 – Sep 4

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 Sierra County

How your county's soil matches Napa Cabbage's growing requirements.

Soil pH

Your soil pH (6.7–7.3) is within Napa Cabbage's preferred range (6.0–7.5).

Soil Texture

The loam soil in Sierra County is excellent for Napa Cabbage — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (3.0%). Annual compost additions will help Napa Cabbage.

How to Plant Napa Cabbage

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

Fall planting: Sow 10 weeks before your first frost date for a fall harvest.

Succession Planting Napa Cabbage

3
successive plantings in your 165-day season

Sow every 6.3 weeks. Last sowing by Aug 08 to harvest before frost.

For a dedicated fall crop, sow by Aug 13.

Plant Water Budget

Plant needs
1.5″/week
Rainfall provides
1.0″/week
You supply
0.6″/week
Watering frequency 1-2 times/week
Season total 827 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Napa Cabbage

Napa Cabbage needs approximately 1.5 inches of water per week (6.5" per month). Here's how your county's rainfall compares month by month.

Month Napa Cabbage Needs Rainfall You Supplement Action
Jan 8.8" 0" ❄️ Dormant
Feb 8.2" 0" ❄️ Dormant
Mar 5.6" 0" ❄️ Dormant
Apr 3.2" 0" ❄️ Dormant
May 6.5" 1.1" 5.4" 🚿 Regular watering
Jun 6.5" 0.2" 6.3" 🚿 Regular watering
Jul 6.5" 0" 6.5" 🚿 Regular watering
Aug 6.5" 0" 6.5" 🚿 Regular watering
Sep 6.5" 0.4" 6.1" 🚿 Regular watering
Oct 6.5" 1.9" 4.6" 🚿 Regular watering
Nov 3.7" 0" ❄️ Dormant
Dec 7.3" 0" ❄️ Dormant

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

Napa Cabbage 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.

Napa Cabbage needs ~650 GDD — county provides 1,650 GDD Excellent fit

Napa Cabbage Planting Timeline — Sierra County, CA

Napa Cabbage Planting Calendar

Activity When Date Range
Start Indoors April 5 Apr 5 – Apr 19
Transplant Outdoors May 10 May 10 – May 24
Direct Sow April 26 Apr 26 – May 17
Harvest July 5 Jul 5 – Aug 9
Fall Sowing August 13 Aug 13 – Aug 27

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1.5"/week · 1-2 times/week

📅 Days to Maturity

55–75 days

🧪 Soil pH

Needs 6–7.5 · Your soil: ideal

🗺️ USDA Zone

Zone 6b

📆 Growing Season

165 days in Sierra County

Growing Tips for Napa Cabbage in Sierra County

Direct sow Napa Cabbage outdoors after May 10 in Sierra County when soil has warmed and frost danger has passed.

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

General growing tips

Best grown as a fall crop. Direct sow in late summer, 60-70 days before first frost. Keep soil evenly moist. Bolt-resistant varieties are available for spring planting.

Companion Planting

Good Companions

Avoid Planting Near

  • Strawberries

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Napa Cabbage in Sierra County, CA?

Sierra County is in Zone 6b with an average last frost of May 10. Plan your Napa Cabbage planting based on this frost date — see the calendar above for exact timing.

What planting zone is Sierra County, CA?

Sierra County, California is in USDA Hardiness Zone 6b. The average last spring frost is May 10 and first fall frost is October 22.

🌱

Your Sierra County Garden Planner — Free

A 24-page printable planner built for Sierra County (Zone 6b). 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 Sierra 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.