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When to Plant Napa Cabbage in Umatilla County, OR

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.

Umatilla County, Oregon is in USDA Zone 6a. The average last spring frost is April 23 and the first fall frost is October 20, giving you a growing season of approximately 180 days.

At an elevation of 2,195 feet, Umatilla County receives approximately 14.6 inches of rainfall annually with predominantly silt loam soil. Summer highs average 86ยฐF, providing good warmth for Napa Cabbage during the growing season. With low rainfall, drip irrigation is essential for growing Napa Cabbage successfully. Mulch heavily to conserve soil moisture.

Umatilla County, OR (Zone 6a) Moderate season
180 days
Last Spring Frost April 23
180 growing days
First Fall Frost October 20

Umatilla County Soil Profile

Soil Type

Silt Loam

Soil pH

5.2-6.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (93 days to spare)
Start indoors: Mar 4 Transplant: Apr 8 🍅 Harvest: Jun 3 – Jul 8
Recommended (50%) ✓ Fits season (89 days to spare)
Start indoors: Mar 19 Transplant: Apr 23 🍅 Harvest: Jun 18 – Jul 23
Safe Start (90%) ✓ Fits season (88 days to spare)
Start indoors: Apr 8 Transplant: May 13 🍅 Harvest: Jul 8 – Aug 12

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.

Plant Water Budget

Plant needs
1.5″/week
Rainfall provides
0.3″/week
You supply
1.2″/week
Watering frequency 2-3 times/week
Season total 1,857 gal / 100 sq ft
Napa Cabbage needs ~942 GDD — county provides 2,610 GDD Excellent fit

Napa Cabbage Planting Timeline โ€” Umatilla County, OR

Napa Cabbage Planting Calendar

Activity When Date Range
Start Indoors March 19 Mar 19 โ€“ Apr 2
Transplant Outdoors April 23 Apr 23 โ€“ May 7
Direct Sow April 9 Apr 9 โ€“ Apr 30
Fall Sowing August 11 Aug 11 โ€“ Aug 25
Harvest June 18 Jun 18 โ€“ Jul 23

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

Month-by-Month Timeline

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

Growing Conditions

Sun

Partial Shade (3-6 hours)

Water

High โ€” keep soil consistently moist

Days to Maturity

55โ€“75 days

Soil pH

6 โ€“ 7.5

USDA Zone

Zone 6a

Growing Season

180 days

Growing Tips for Umatilla County

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

Level Up Your Garden

Frequently Asked Questions

When should I plant Napa Cabbage in Umatilla County, OR?

Umatilla County is in Zone 6a with an average last frost of April 23. Plan your Napa Cabbage planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Umatilla County, OR?

Umatilla County, Oregon is in USDA Hardiness Zone 6a. The average last spring frost is April 23 and first fall frost is October 20.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Umatilla County gardeners in Zone 6a organize planting dates, track what's growing, and never miss a planting window.

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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 Umatilla County, OR. Local conditions may vary. Last updated: April 2026.