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When to plant Celeriac in Mahnomen County, MN

The best window to plant Celeriac in Mahnomen County, is May 6–May 27, when soil warms to 50°F. Last frost typically hits May 13; first frost September 27. A second sowing from July 5 to July 19 extends the harvest into fall.

When to Plant Celeriac in Mahnomen County, MN

Mahnomen County, Minnesota Zone 4a June

What to do in June

Each item below is timed to Mahnomen County, Minnesota's frost dates and soil temperatures. Skip nothing, stress about nothing.

Avg. last frost May 13
Avg. first frost September 27
Soil temp (4") 60°F
Watering Low
Pest pressure Moderate
Daylight 15.7 hrs
  1. Indoor seed-starting week for celeriac

    You're about 14 weeks out from your last frost — the perfect window to get these germinating indoors.

July will be here before you know it — start on
  • Fall sowing: celeriac

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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.

Mahnomen County, Minnesota is in USDA Zone 4a. The average last spring frost is May 13 and the first fall frost is September 27, giving you a growing season of approximately 137 days.

At an elevation of 1,223 feet, Mahnomen County receives approximately 33.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 80°F, so choose short-season varieties of Celeriac to ensure they mature before fall.

Mahnomen County, MN (Zone 4a) Short season
137 days
Last Spring Frost May 13
137 growing days
First Fall Frost September 27

Mahnomen County Soil Profile

Soil Type

Silt Loam

Soil pH

5.9-7

Drainage

Well Drained

Celeriac Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 26 Transplant: May 7 🍅 Harvest: Aug 20 – Sep 24
Recommended (50%) ✗ May not fit
Start indoors: Apr 1 Transplant: May 13 🍅 Harvest: Aug 26 – Sep 30
Safe Start (90%) ✓ Fits season (4 days to spare)
Start indoors: Apr 11 Transplant: May 23 🍅 Harvest: Sep 5 – Oct 10

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 Mahnomen County

How your county's soil matches Celeriac's growing requirements.

Soil pH

Your soil pH (5.9–7.0) overlaps with Celeriac's range (6.0–7.0), though not a perfect match.

Soil Texture

The silt loam soil in Mahnomen County is excellent for Celeriac — good drainage, moisture retention, and nutrient holding capacity.

Drainage

Celeriac is a heavy drinker but your soil drains very quickly. Mulch heavily and consider drip irrigation.

Organic Matter

Organic matter is excellent (4.0%) — Celeriac will thrive.

How to Plant Celeriac

1"
Planting Depth
15"
Between Plants
24"
Between Rows

Fall planting: Sow 12 weeks before your first frost date for a fall harvest.

Celeriac Water Budget

Plant needs
0.9″/week
Rainfall provides
1.0″/week
You supply
0.2″/week
Watering frequency Only during dry spells
Season total 189 gal / 100 sq ft

Monthly Watering Guide for Celeriac

Celeriac needs approximately 0.9 inches of water per week (3.9" per month). Here's how your county's rainfall compares month by month.

Month Celeriac Needs Rainfall You Supplement Action
Jan 1.3" 0" ❄️ Dormant
Feb 1.5" 0" ❄️ Dormant
Mar 2.2" 0" ❄️ Dormant
Apr 2.9" 0" ❄️ Dormant
May 3.9" 4.3" 0" ✅ Rainfall sufficient
Jun 3.9" 3.8" 0.1" 💧 Light watering
Jul 3.9" 3.7" 0.2" 💧 Light watering
Aug 3.9" 3.6" 0.3" 💧 Light watering
Sep 3.9" 3.1" 0.8" 💧 Light watering
Oct 2.4" 0" ❄️ Dormant
Nov 2.4" 0" ❄️ Dormant
Dec 2" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Mahnomen County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Celeriac 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.

Celeriac needs ~1,100 GDD — county provides 1,370 GDD Good fit

Celeriac Planting Timeline — Mahnomen County, MN

Celeriac Planting Calendar

Activity When Date Range
Start Indoors April 1 Apr 1 – Apr 15
Transplant Outdoors May 13 May 13 – May 27
Direct Sow May 6 May 6 – May 27
Harvest August 26 Aug 26 – Sep 30
Fall Sowing July 5 Jul 5 – Jul 19

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.9"/week · Only during dry spells

📅 Days to Maturity

100–120 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 4a

📆 Growing Season

137 days in Mahnomen County

Growing Tips for Celeriac in Mahnomen County

Direct sow Celeriac outdoors after May 13 in Mahnomen County when soil has warmed and frost danger has passed.

Common pests for Celeriac in this region include carrot rust fly and parsleyworm. Use row covers early in the season and inspect plants weekly.

General growing tips

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

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Celeriac in Mahnomen County, MN?

Mahnomen County is in Zone 4a with an average last frost of May 13. Plan your Celeriac planting based on this frost date — see the calendar above for exact timing.

What planting zone is Mahnomen County, MN?

Mahnomen County, Minnesota is in USDA Hardiness Zone 4a. The average last spring frost is May 13 and first fall frost is September 27.

When should I plant Celeriac in Mahnomen County, MN?

In Mahnomen County, MN, plant Celeriac after the last frost (around May 13) and before the first frost (around September 27). Best results when soil holds above 50°F.

What growing zone is Mahnomen County, MN for Celeriac?

Mahnomen County sits in USDA Zone 4a. Celeriac grows reliably in zones 3a through 9b, so it's a good fit here.

Can Celeriac grow in Mahnomen County's climate?

Yes — Celeriac grows well in Mahnomen County's temperate climate. Mahnomen County averages a 137-day frost-free season, with last frost around May 13 and first frost around September 27.

🌱

Your Mahnomen County Garden Planner — Free

A 22-page printable planner built for Mahnomen County (Zone 4a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

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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 Mahnomen County, MN. Local conditions may vary. Last updated: June 2026.

Sources & credits

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