When to Plant Napa Cabbage in Jefferson County, WI
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.
Jefferson County, Wisconsin is in USDA Zone 5a. The average last spring frost is April 27 and the first fall frost is October 12, giving you a growing season of approximately 168 days.
At an elevation of 613 feet, Jefferson County receives approximately 36.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 87°F, providing good warmth for Napa Cabbage during the growing season.
Jefferson County Soil Profile
Soil Type
Silt Loam
Soil pH
6.3-6.7
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 Jefferson County
How your county's soil matches Napa Cabbage's growing requirements.
Soil pH
Your soil pH (6.3–6.7) is within Napa Cabbage's preferred range (6.0–7.5).
Soil Texture
The silt loam soil in Jefferson County is excellent for Napa Cabbage — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Napa Cabbage is a heavy drinker but your soil drains very quickly. Mulch heavily and consider drip irrigation.
Organic Matter
Organic matter is excellent (4.1%) — Napa Cabbage will thrive.
How to Plant Napa Cabbage
Fall planting: Sow 10 weeks before your first frost date for a fall harvest.
Succession Planting Napa Cabbage
Sow every 6.3 weeks. Last sowing by Jul 29 to harvest before frost.
For a dedicated fall crop, sow by Aug 03.
Plant Water Budget
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 | — | 1.7" | 0" | ❄️ Dormant |
| Feb | — | 1.6" | 0" | ❄️ Dormant |
| Mar | — | 2.4" | 0" | ❄️ Dormant |
| Apr | 6.5" | 2.9" | 3.6" | 🚿 Regular watering |
| May | 6.5" | 4.6" | 1.9" | 💧 Light watering |
| Jun | 6.5" | 4.4" | 2.1" | 💧 Light watering |
| Jul | 6.5" | 3.9" | 2.6" | 💧 Light watering |
| Aug | 6.5" | 4.2" | 2.3" | 💧 Light watering |
| Sep | 6.5" | 3.6" | 2.9" | 💧 Light watering |
| Oct | 6.5" | 2.7" | 3.8" | 🚿 Regular watering |
| Nov | — | 2.7" | 0" | ❄️ Dormant |
| Dec | — | 2.2" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Jefferson 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 — Jefferson County, WI
Napa Cabbage Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 23 | Mar 23 – Apr 6 |
| Transplant Outdoors | April 27 | Apr 27 – May 11 |
| Direct Sow | April 13 | Apr 13 – May 4 |
| Harvest | June 22 | Jun 22 – Jul 27 |
| Fall Sowing | August 3 | Aug 3 – Aug 17 |
Plant 1" deep · 15" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Start Indoors Transplant Outdoors Direct Sow |
| May | Transplant Outdoors Direct Sow |
| June | Harvest |
| July | Harvest |
| August | Fall Sowing |
| September | — |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Partial Shade (3-6 hours)
💧 Water
1.5"/week · 2-3 times/week
📅 Days to Maturity
55–75 days
🧪 Soil pH
Needs 6–7.5 · Your soil: ideal
🗺️ USDA Zone
Zone 5a
📆 Growing Season
168 days in Jefferson County
Growing Tips for Napa Cabbage in Jefferson County
Direct sow Napa Cabbage outdoors after April 27 in Jefferson 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
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Napa Cabbage in Other Locations
Frequently Asked Questions
When should I plant Napa Cabbage in Jefferson County, WI?
Jefferson County is in Zone 5a with an average last frost of April 27. Plan your Napa Cabbage planting based on this frost date — see the calendar above for exact timing.
What planting zone is Jefferson County, WI?
Jefferson County, Wisconsin is in USDA Hardiness Zone 5a. The average last spring frost is April 27 and first fall frost is October 12.
Plan Your Garden with Confidence
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