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When to Plant Napa Cabbage in Butte County, ID

Butte County, Idaho Zone 5a May

Your May planting checklist for Butte County, Idaho

Your garden in Butte County, Idaho is working on a schedule, even when you're not. Here's where you should be this May.

Avg. last frost June 1
Avg. first frost September 14
Soil temp (4") 34°F
Watering Moderate
Pest pressure Low
Daylight 14.5 hrs
  1. Seed napa cabbage outdoors

    Sow every 2 weeks for a continuous harvest. A single big planting means a single big glut.

Get ahead of June
  • Transplants going out: 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.

Butte County, Idaho is in USDA Zone 5a. The average last spring frost is June 1 and the first fall frost is September 14, giving you a growing season of approximately 105 days.

At an elevation of 7,254 feet, Butte County receives approximately 24 inches of rainfall annually with predominantly loam soil. Summer highs average 84°F, so choose short-season varieties of Napa Cabbage to ensure they mature before fall.

Butte County, ID (Zone 5a) Short season
105 days
Last Spring Frost June 1
105 growing days
First Fall Frost September 14

Butte County Soil Profile

Soil Type

Loam

Soil pH

6.8-8.4

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (19 days to spare)
Start indoors: Apr 16 Transplant: May 21 🍅 Harvest: Jul 16 – Aug 20
Recommended (50%) ✓ Fits season (14 days to spare)
Start indoors: Apr 27 Transplant: Jun 1 🍅 Harvest: Jul 27 – Aug 31
Safe Start (90%) ✓ Fits season (19 days to spare)
Start indoors: May 13 Transplant: Jun 17 🍅 Harvest: Aug 12 – Sep 16

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 Butte County

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

Soil pH

Your soil pH (6.8–8.4) is more alkaline than Napa Cabbage prefers (6.0–7.5). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.4%). 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

2
successive plantings in your 105-day season

Sow every 6.3 weeks. Last sowing by Jul 01 to harvest before frost.

For a dedicated fall crop, sow by Jul 06.

Plant Water Budget

Plant needs
1.5″/week
Rainfall provides
1.0″/week
You supply
0.7″/week
Watering frequency 1-2 times/week
Season total 606 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — 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 1.8" 0" ❄️ Dormant
Feb 1.4" 0" ❄️ Dormant
Mar 2.1" 0" ❄️ Dormant
Apr 2.4" 0" ❄️ Dormant
May 3" 0" ❄️ Dormant
Jun 6.5" 1.9" 4.6" 🚿 Regular watering
Jul 6.5" 1.9" 4.6" 🚿 Regular watering
Aug 6.5" 2.7" 3.8" 🚿 Regular watering
Sep 6.5" 1.7" 4.8" 🚿 Regular watering
Oct 2.2" 0" ❄️ Dormant
Nov 1.6" 0" ❄️ Dormant
Dec 1.4" 0" ❄️ Dormant

Water needs are for active growing months only (Jun–Sep in Butte 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 ~845 GDD — county provides 1,365 GDD Excellent fit

Napa Cabbage Planting Timeline — Butte County, ID

Napa Cabbage Planting Calendar

Activity When Date Range
Start Indoors April 27 Apr 27 – May 11
Transplant Outdoors June 1 Jun 1 – Jun 15
Direct Sow May 18 May 18 – Jun 8
Harvest July 27 Jul 27 – Aug 31
Fall Sowing July 6 Jul 6 – Jul 20

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

Month-by-Month Timeline

MonthActivities
January
February
March
April Start Indoors
May Start Indoors Direct Sow
June Transplant Outdoors Direct Sow
July Fall Sowing Harvest
August 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: too_alkaline

🗺️ USDA Zone

Zone 5a

📆 Growing Season

105 days in Butte County

Growing Tips for Napa Cabbage in Butte County

Direct sow Napa Cabbage outdoors after June 01 in Butte 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.

Butte County receives only 24" of rain annually. Napa Cabbage needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

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 Butte County, ID?

Butte County is in Zone 5a with an average last frost of June 1. Plan your Napa Cabbage planting based on this frost date — see the calendar above for exact timing.

What planting zone is Butte County, ID?

Butte County, Idaho is in USDA Hardiness Zone 5a. The average last spring frost is June 1 and first fall frost is September 14.

🌱

Your Butte County Garden Planner — Free

A 24-page printable planner built for Butte 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 Butte 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.