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When to Plant Chinese Cabbage in Jefferson County, ID

Jefferson County, Idaho Zone 5a May

This month in Jefferson County, Idaho

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

Avg. last frost May 22
Avg. first frost September 21
Soil temp (4") 43°F
Watering High
Pest pressure Low
Daylight 14.5 hrs
  1. Plant out chinese cabbage

    Frost risk is low now in Jefferson County, Idaho. If you've been covering beds overnight, you can stop.

  2. Put chinese cabbage seeds straight in the ground

    Rake a smooth bed, make a shallow furrow, drop seeds at the spacing on the packet, water gently, walk away.

June prep starts now
  • Starting indoors: chinese cabbage

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Chinese cabbage (Napa cabbage) forms elongated, barrel-shaped heads with tender, mild-flavored leaves. It is a staple in Asian cooking, particularly for kimchi.

Jefferson County, Idaho is in USDA Zone 5a. The average last spring frost is May 22 and the first fall frost is September 21, giving you a growing season of approximately 122 days.

At an elevation of 5,094 feet, Jefferson County receives approximately 18 inches of rainfall annually with predominantly loam soil. Summer highs average 87°F, providing good warmth for Chinese Cabbage during the growing season. With low rainfall, drip irrigation is essential for growing Chinese Cabbage successfully. Mulch heavily to conserve soil moisture.

Jefferson County, ID (Zone 5a) Short season
122 days
Last Spring Frost May 22
122 growing days
First Fall Frost September 21
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Jefferson County Soil Profile

Soil Type

Loam

Soil pH

6.3-7.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (39 days to spare)
Start indoors: Apr 4 Transplant: May 9 🍅 Harvest: Jul 4 – Aug 1
Recommended (50%) ✓ Fits season (38 days to spare)
Start indoors: Apr 17 Transplant: May 22 🍅 Harvest: Jul 17 – Aug 14
Safe Start (90%) ✓ Fits season (34 days to spare)
Start indoors: May 13 Transplant: Jun 17 🍅 Harvest: Aug 12 – Sep 9

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 Jefferson County

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

Soil pH

Your soil pH (6.3–7.8) overlaps with Chinese Cabbage's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.4%). Annual compost additions will help Chinese Cabbage.

How to Plant Chinese 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 Chinese Cabbage

2
successive plantings in your 122-day season

Sow every 5.7 weeks. Last sowing by Jul 13 to harvest before frost.

For a dedicated fall crop, sow by Jul 13.

Plant Water Budget

Plant needs
1.5″/week
Rainfall provides
0.6″/week
You supply
1.1″/week
Watering frequency 2-3 times/week
Season total 1,147 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Chinese Cabbage

Chinese 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 Chinese Cabbage Needs Rainfall You Supplement Action
Jan 1.1" 0" ❄️ Dormant
Feb 1.2" 0" ❄️ Dormant
Mar 1.4" 0" ❄️ Dormant
Apr 2" 0" ❄️ Dormant
May 6.5" 1.9" 4.6" 🚿 Regular watering
Jun 6.5" 1.4" 5.1" 🚿 Regular watering
Jul 6.5" 1.4" 5.1" 🚿 Regular watering
Aug 6.5" 2" 4.5" 🚿 Regular watering
Sep 6.5" 1.6" 4.9" 🚿 Regular watering
Oct 1.6" 0" ❄️ Dormant
Nov 1.3" 0" ❄️ Dormant
Dec 1" 0" ❄️ Dormant

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

Chinese 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.

Chinese Cabbage needs ~915 GDD — county provides 1,860 GDD Excellent fit

Chinese Cabbage Planting Timeline — Jefferson County, ID

Chinese Cabbage Planting Calendar

Activity When Date Range
Start Indoors April 17 Apr 17 – May 1
Transplant Outdoors May 22 May 22 – Jun 5
Direct Sow May 8 May 8 – May 29
Harvest July 17 Jul 17 – Aug 14
Fall Sowing July 13 Jul 13 – Jul 27

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

Month-by-Month Timeline

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

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1.5"/week · 2-3 times/week

📅 Days to Maturity

50–70 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 5a

📆 Growing Season

122 days in Jefferson County

Growing Tips for Chinese Cabbage in Jefferson County

Direct sow Chinese Cabbage outdoors after May 22 in Jefferson County when soil has warmed and frost danger has passed.

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

Jefferson County receives only 18" of rain annually. Chinese Cabbage needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Best grown as a fall crop to avoid bolting. Start seeds indoors or direct sow in late summer. Keep soil consistently moist and provide shade in warm weather.

Companion Planting

Good Companions

Avoid Planting Near

  • Strawberries
  • Tomatoes

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Chinese Cabbage in Jefferson County, ID?

Jefferson County is in Zone 5a with an average last frost of May 22. Plan your Chinese Cabbage planting based on this frost date — see the calendar above for exact timing.

What planting zone is Jefferson County, ID?

Jefferson County, Idaho is in USDA Hardiness Zone 5a. The average last spring frost is May 22 and first fall frost is September 21.

🌱

Your Jefferson County Garden Planner — Free

A 24-page printable planner built for Jefferson County (Zone 5a). 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 Jefferson County, ID. 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.