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When to Plant Sunchoke in Wahkiakum County, WA

Sunchokes (Jerusalem artichokes) are a native sunflower relative grown for their knobby, nutty-flavored tubers. They are extremely productive and nearly impossible to eradicate.

Wahkiakum County, Washington is in USDA Zone 8a. The average last spring frost is April 13 and the first fall frost is November 4, giving you a growing season of approximately 205 days.

At an elevation of 180 feet, Wahkiakum County receives approximately 35.3 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85ยฐF, providing good warmth for Sunchoke during the growing season.

Wahkiakum County, WA (Zone 8a) Long season
205 days
Last Spring Frost April 13
205 growing days
First Fall Frost November 4

Wahkiakum County Soil Profile

Soil Type

Silt Loam

Soil pH

5.4-6.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (28 days to spare)
Transplant: Apr 16 🍅 Harvest: Aug 6 – Oct 1
Recommended (50%) ✓ Fits season (23 days to spare)
Transplant: Apr 27 🍅 Harvest: Aug 17 – Oct 12
Safe Start (90%) ✓ Fits season (35 days to spare)
Transplant: May 14 🍅 Harvest: Sep 3 – Oct 29

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
1.0″/week
Rainfall provides
0.7″/week
You supply
0.3″/week
Watering frequency Only during dry spells
Season total 505 gal / 100 sq ft
Sunchoke needs ~1,788 GDD — county provides 2,818 GDD Excellent fit

Sunchoke Planting Timeline โ€” Wahkiakum County, WA

Sunchoke Planting Calendar

Activity When Date Range
Transplant Outdoors April 27 Apr 27 โ€“ May 11
Harvest August 17 Aug 17 โ€“ Oct 12

Plant 1" deep ยท 30" apart ยท Rows 42" apart

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March โ€”
April Transplant Outdoors
May Transplant Outdoors
June โ€”
July โ€”
August Harvest
September Harvest
October Harvest
November โ€”
December โ€”

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

110โ€“150 days

Soil pH

6 โ€“ 7.5

USDA Zone

Zone 8a

Growing Season

205 days

Growing Tips for Wahkiakum County

Plant tubers 4 inches deep in early spring. Contain plants with barriers as they spread aggressively. Harvest after frost or leave in ground and dig as needed through winter.

Companion Planting

Good Companions

Level Up Your Garden

Frequently Asked Questions

When should I plant Sunchoke in Wahkiakum County, WA?

Wahkiakum County is in Zone 8a with an average last frost of April 13. Plan your Sunchoke planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Wahkiakum County, WA?

Wahkiakum County, Washington is in USDA Hardiness Zone 8a. The average last spring frost is April 13 and first fall frost is November 4.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Wahkiakum County gardeners in Zone 8a 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 Wahkiakum County, WA. Local conditions may vary. Last updated: April 2026.