When to Plant Napa Cabbage in Custer County, ID
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.
Custer County, Idaho is in USDA Zone 4a. The average last spring frost is June 18 and the first fall frost is September 5, giving you a growing season of approximately 79 days.
At an elevation of 5,189 feet, Custer County receives approximately 20.6 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.
Custer County Soil Profile
Soil Type
Loam
Soil pH
6.3-8
Drainage
Well Drained
Plant Planting Risk Windows
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 Custer County
How your county's soil matches Napa Cabbage's growing requirements.
Soil pH
Your soil pH (6.3–8.0) overlaps with Napa Cabbage's range (6.0–7.5), though not a perfect match.
Soil Texture
The loam soil in Custer County is excellent for Napa Cabbage — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (2.3%). Annual compost additions will help Napa Cabbage.
How to Plant Napa Cabbage
Fall planting: Sow 12 weeks before your first frost date for a fall harvest.
Plant Water Budget
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 | — | 1.3" | 0" | ❄️ Dormant |
| Feb | — | 1.3" | 0" | ❄️ Dormant |
| Mar | — | 1.7" | 0" | ❄️ Dormant |
| Apr | — | 2.4" | 0" | ❄️ Dormant |
| May | — | 2.3" | 0" | ❄️ Dormant |
| Jun | 6.5" | 1.5" | 5" | 🚿 Regular watering |
| Jul | 6.5" | 2" | 4.5" | 🚿 Regular watering |
| Aug | 6.5" | 2.1" | 4.4" | 🚿 Regular watering |
| Sep | 6.5" | 1.7" | 4.8" | 🚿 Regular watering |
| Oct | — | 1.6" | 0" | ❄️ Dormant |
| Nov | — | 1.4" | 0" | ❄️ Dormant |
| Dec | — | 1.2" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Jun–Sep in Custer 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 Planting Timeline — Custer County, ID
Napa Cabbage Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | May 7 | May 7 – May 21 |
| Transplant Outdoors | June 18 | Jun 18 – Jul 2 |
| Direct Sow | June 11 | Jun 11 – Jul 2 |
| Harvest | August 13 | Aug 13 – Sep 17 |
| Fall Sowing | June 13 | Jun 13 – Jun 27 |
Plant 1" deep · 15" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | — |
| May | Start Indoors |
| June | Transplant Outdoors Direct Sow Fall Sowing |
| July | Transplant Outdoors Direct Sow |
| August | Harvest |
| September | Harvest |
| 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: acceptable
🗺️ USDA Zone
Zone 4a
📆 Growing Season
79 days in Custer County
Growing Tips for Napa Cabbage in Custer County
Direct sow Napa Cabbage outdoors after June 18 in Custer County when soil has warmed and frost danger has passed.
Your 79.0-day growing season in Custer County is tight for Napa Cabbage (55.0-75.0 days to maturity). Start indoors and choose early-maturing varieties.
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.
Custer County receives only 21" 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
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Napa Cabbage in Other Locations
Frequently Asked Questions
When should I plant Napa Cabbage in Custer County, ID?
Custer County is in Zone 4a with an average last frost of June 18. Plan your Napa Cabbage planting based on this frost date — see the calendar above for exact timing.
What planting zone is Custer County, ID?
Custer County, Idaho is in USDA Hardiness Zone 4a. The average last spring frost is June 18 and first fall frost is September 5.
Plan Your Garden with Confidence
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