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When to Plant Celeriac in Keweenaw County, MI

Keweenaw County, Michigan Zone 5b May

Your May game plan for Keweenaw County, Michigan

A quick May briefing for Keweenaw County, Michigan gardeners — what's urgent, what's next, and what can wait.

Avg. last frost May 19
Avg. first frost October 1
Soil temp (4") 53°F
Watering Low
Pest pressure Low
Daylight 14.9 hrs
  1. Move celeriac into the garden

    Pick a cloudy afternoon or evening to plant. Less transplant shock, and your seedlings will barely blink.

  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
  • Starting indoors: 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.

Keweenaw County, Michigan is in USDA Zone 5b. The average last spring frost is May 19 and the first fall frost is October 1, giving you a growing season of approximately 135 days.

At an elevation of 1,035 feet, Keweenaw County receives approximately 40.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 81°F, so choose short-season varieties of Celeriac to ensure they mature before fall.

Keweenaw County, MI (Zone 5b) Short season
135 days
Last Spring Frost May 19
135 growing days
First Fall Frost October 1
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Keweenaw County Soil Profile

Soil Type

Silt Loam

Soil pH

6.1-6.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Apr 10 Transplant: May 15 🍅 Harvest: Aug 28 – Oct 2
Recommended (50%) ✗ May not fit
Start indoors: Apr 14 Transplant: May 19 🍅 Harvest: Sep 1 – Oct 6
Safe Start (90%) ✗ May not fit
Start indoors: Apr 30 Transplant: Jun 4 🍅 Harvest: Sep 17 – Oct 22

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 Keweenaw County

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

Soil pH

Your soil pH (6.1–6.9) is within Celeriac's preferred range (6.0–7.0).

Soil Texture

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

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 10 weeks before your first frost date for a fall harvest.

Plant Water Budget

Plant needs
0.9″/week
Rainfall provides
1.3″/week
Watering frequency Natural rainfall sufficient
Season total 0 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 1.7" 0" ❄️ Dormant
Feb 1.8" 0" ❄️ Dormant
Mar 2.6" 0" ❄️ Dormant
Apr 3.7" 0" ❄️ Dormant
May 3.9" 4.2" 0" ✅ Rainfall sufficient
Jun 3.9" 4.9" 0" ✅ Rainfall sufficient
Jul 3.9" 5" 0" ✅ Rainfall sufficient
Aug 3.9" 4.7" 0" ✅ Rainfall sufficient
Sep 3.9" 3.7" 0.2" 💧 Light watering
Oct 3.9" 3.2" 0.7" 💧 Light watering
Nov 2.9" 0" ❄️ Dormant
Dec 2.4" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Keweenaw 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 ~1,182 GDD — county provides 1,451 GDD Good fit

Celeriac Planting Timeline — Keweenaw County, MI

Celeriac Planting Calendar

Activity When Date Range
Start Indoors April 14 Apr 14 – Apr 28
Transplant Outdoors May 19 May 19 – Jun 2
Direct Sow May 5 May 5 – May 26
Harvest September 1 Sep 1 – Oct 6
Fall Sowing July 23 Jul 23 – Aug 6

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
July Fall Sowing
August Fall Sowing
September Harvest
October Harvest
November
December
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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: ideal

🗺️ USDA Zone

Zone 5b

📆 Growing Season

135 days in Keweenaw County

Growing Tips for Celeriac in Keweenaw County

Direct sow Celeriac outdoors after May 19 in Keweenaw 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 Keweenaw County, MI?

Keweenaw County is in Zone 5b with an average last frost of May 19. Plan your Celeriac planting based on this frost date — see the calendar above for exact timing.

What planting zone is Keweenaw County, MI?

Keweenaw County, Michigan is in USDA Hardiness Zone 5b. The average last spring frost is May 19 and first fall frost is October 1.

🌱

Your Keweenaw County Garden Planner — Free

A 24-page printable planner built for Keweenaw County (Zone 5b). 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 Keweenaw County, MI. 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.