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When to Plant Celeriac in Polk County, WI

Celeriac is a celery relative grown for its knobby, flavorful root rather than its stalks. It has a rich celery flavor and is excellent roasted, mashed, or in soups.

Polk County, Wisconsin is in USDA Zone 4a. The average last spring frost is May 12 and the first fall frost is September 29, giving you a growing season of approximately 140 days.

At an elevation of 582 feet, Polk County receives approximately 40 inches of rainfall annually with predominantly silt loam soil. Summer highs average 82ยฐF, so choose short-season varieties of Celeriac to ensure they mature before fall.

Polk County, WI (Zone 4a) Short season
140 days
Last Spring Frost May 12
140 growing days
First Fall Frost September 29

Polk County Soil Profile

Soil Type

Silt Loam

Soil pH

6-6.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (7 days to spare)
Start indoors: Mar 19 Transplant: Apr 30 🍅 Harvest: Aug 13 – Sep 17
Recommended (50%) ✓ Fits season (0 days to spare)
Start indoors: Mar 31 Transplant: May 12 🍅 Harvest: Aug 25 – Sep 29
Safe Start (90%) ✓ Fits season (6 days to spare)
Start indoors: Apr 8 Transplant: May 20 🍅 Harvest: Sep 2 – Oct 7

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
1.2″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 449 gal / 100 sq ft
Drought risk

Water stress score is 6/10 โ€” consider drought-tolerant varieties and mulching

Celeriac needs ~1,265 GDD — county provides 1,610 GDD Good fit

Celeriac Planting Timeline โ€” Polk County, WI

Celeriac Planting Calendar

Activity When Date Range
Start Indoors March 31 Mar 31 โ€“ Apr 14
Transplant Outdoors May 12 May 12 โ€“ May 26
Direct Sow May 5 May 5 โ€“ May 26
Fall Sowing July 7 Jul 7 โ€“ Jul 21
Harvest August 25 Aug 25 โ€“ Sep 29

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
May Transplant Outdoors Direct Sow
June โ€”
July Fall Sowing
August Harvest
September Harvest
October โ€”
November โ€”
December โ€”

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

High โ€” keep soil consistently moist

Days to Maturity

100โ€“120 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 4a

Growing Season

140 days

Growing Tips for Polk County

Start seeds indoors 10-12 weeks before last frost. Remove side roots as they develop to encourage a single large bulb. Harvest after a light frost for best flavor.

Companion Planting

Good Companions

Avoid Planting Near

  • Carrots
  • Parsnip

Level Up Your Garden

Frequently Asked Questions

When should I plant Celeriac in Polk County, WI?

Polk County is in Zone 4a with an average last frost of May 12. Plan your Celeriac planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Polk County, WI?

Polk County, Wisconsin is in USDA Hardiness Zone 4a. The average last spring frost is May 12 and first fall frost is September 29.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Polk County gardeners in Zone 4a 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 Polk County, WI. Local conditions may vary. Last updated: April 2026.