Blog

When to Plant Celeriac in Roseau County, MN

Roseau County, Minnesota Zone 3b May

Roseau County, Minnesota gardeners: here's your May plan

We've pulled the most time-sensitive tasks for Roseau County, Minnesota this May and put them front and centre. Tackle them in order.

Avg. last frost May 21
Avg. first frost September 22
Soil temp (4") 51°F
Watering Low
Pest pressure Low
Daylight 15 hrs
  1. Set out celeriac seedlings

    Plant tomatoes deep — bury the stem up to the first true leaves to grow extra roots. Everything else goes in at the same depth it grew in the tray.

  2. Seed celeriac outdoors

    Mark the row. Birds and stray feet both have opinions about unmarked beds.

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

Instant PDF download. No spam, unsubscribe any time.

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.

Roseau County, Minnesota is in USDA Zone 3b. The average last spring frost is May 21 and the first fall frost is September 22, giving you a growing season of approximately 124 days.

At an elevation of 655 feet, Roseau County receives approximately 32 inches of rainfall annually with predominantly silt loam soil. Summer highs average 79°F, so choose short-season varieties of Celeriac to ensure they mature before fall.

Roseau County, MN (Zone 3b) Short season
124 days
Last Spring Frost May 21
124 growing days
First Fall Frost September 22
Share this guide:

Roseau County Soil Profile

Soil Type

Silt Loam

Soil pH

5.9-7.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (0 days to spare)
Start indoors: Mar 30 Transplant: May 11 🍅 Harvest: Aug 24 – Sep 14
Recommended (50%) ✗ May not fit
Start indoors: Apr 9 Transplant: May 21 🍅 Harvest: Sep 3 – Sep 24
Safe Start (90%) ✓ Fits season (0 days to spare)
Start indoors: Apr 23 Transplant: Jun 4 🍅 Harvest: Sep 17 – Oct 8

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 Roseau County

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

Soil pH

Your soil pH (5.9–7.2) overlaps with Celeriac's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is excellent (5.1%) — 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.

Plant Water Budget

Plant needs
0.9″/week
Rainfall provides
1.1″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

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 1.2" 0" ❄️ Dormant
Feb 1.6" 0" ❄️ Dormant
Mar 1.8" 0" ❄️ Dormant
Apr 2.9" 0" ❄️ Dormant
May 3.9" 3.9" 0" ✅ Rainfall sufficient
Jun 3.9" 4.3" 0" ✅ Rainfall sufficient
Jul 3.9" 3.8" 0.1" 💧 Light watering
Aug 3.9" 3.7" 0.2" 💧 Light watering
Sep 3.9" 2.4" 1.5" 💧 Light watering
Oct 2.7" 0" ❄️ Dormant
Nov 1.9" 0" ❄️ Dormant
Dec 1.7" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Roseau 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 ~1,018 GDD — county provides 1,147 GDD Good fit

Celeriac Planting Timeline — Roseau County, MN

Celeriac Planting Calendar

Activity When Date Range
Start Indoors April 9 Apr 9 – Apr 23
Transplant Outdoors May 21 May 21 – Jun 4
Direct Sow May 14 May 14 – Jun 4
Harvest September 3 Sep 3 – Sep 24
Fall Sowing June 30 Jun 30 – Jul 14

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 Transplant Outdoors Direct Sow Fall Sowing
July Fall Sowing
August
September Harvest
October
November
December
Share this guide:

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.9"/week · Natural rainfall sufficient

📅 Days to Maturity

100–120 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 3b

📆 Growing Season

124 days in Roseau County

Growing Tips for Celeriac in Roseau County

Direct sow Celeriac outdoors after May 21 in Roseau County when soil has warmed and frost danger has passed.

Your 124.0-day growing season in Roseau County is tight for Celeriac (100.0-120.0 days to maturity). Start indoors and choose early-maturing varieties.

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 Roseau County, MN?

Roseau County is in Zone 3b with an average last frost of May 21. Plan your Celeriac planting based on this frost date — see the calendar above for exact timing.

What planting zone is Roseau County, MN?

Roseau County, Minnesota is in USDA Hardiness Zone 3b. The average last spring frost is May 21 and first fall frost is September 22.

🌱

Your Roseau County Garden Planner — Free

A 24-page printable planner built for Roseau County (Zone 3b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

Instant PDF download. No spam, unsubscribe any time.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Roseau County, MN. Local conditions may vary. Last updated: May 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.