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When to plant Celeriac in Iosco County, MI

Celeriac planted in Iosco County between April 30 and May 21 matures in 100–120 days — well before the October 3 first frost. A second sowing from July 25 to August 8 extends the harvest into fall.

When to Plant Celeriac in Iosco County, MI

Iosco County, Michigan Zone 5b August

Your August game plan for Iosco County, Michigan

Your Iosco County, Michigan garden is entering a new phase. Here's what's on the schedule for August and why each task matters now.

Avg. last frost May 14
Avg. first frost October 3
Soil temp (4") 78°F
Watering Low
Pest pressure High
Daylight 13.8 hrs
  1. Start harvesting celeriac

    This is the payoff month. Bring a basket, bring a friend, and get into the beds.

Looking ahead to September
  • First harvests: 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.

Iosco County, Michigan is in USDA Zone 5b. The average last spring frost is May 14 and the first fall frost is October 3, giving you a growing season of approximately 142 days.

At an elevation of 696 feet, Iosco County receives approximately 37.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 88°F, providing good warmth for Celeriac during the growing season.

Iosco County, MI (Zone 5b) Short season
142 days
Last Spring Frost May 14
142 growing days
First Fall Frost October 3

Iosco County Soil Profile

Soil Type

Silt Loam

Soil pH

6.2-6.9

Drainage

Well Drained

Celeriac Planting Risk Windows

Early Start (70% safe) ✓ Fits season (3 days to spare)
Start indoors: Apr 3 Transplant: May 8 🍅 Harvest: Aug 21 – Sep 25
Recommended (50%) ✓ Fits season (2 days to spare)
Start indoors: Apr 9 Transplant: May 14 🍅 Harvest: Aug 27 – Oct 1
Safe Start (90%) ✓ Fits season (2 days to spare)
Start indoors: Apr 23 Transplant: May 28 🍅 Harvest: Sep 10 – Oct 15

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 Iosco County

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

Soil pH

Your soil pH (6.2–6.9) is within Celeriac's preferred range (6.0–7.0).

Soil Texture

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

Organic Matter

Organic matter is excellent (4.4%) — 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.

Celeriac Water Budget

Plant needs
0.9″/week
Rainfall provides
1.1″/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 1.6" 0" ❄️ Dormant
Mar 2.9" 0" ❄️ Dormant
Apr 3.8" 0" ❄️ Dormant
May 3.9" 4.7" 0" ✅ Rainfall sufficient
Jun 3.9" 4.7" 0" ✅ Rainfall sufficient
Jul 3.9" 3.6" 0.3" 💧 Light watering
Aug 3.9" 4" 0" ✅ Rainfall sufficient
Sep 3.9" 2.9" 1" 💧 Light watering
Oct 3.9" 2.7" 1.2" 💧 Light watering
Nov 2.8" 0" ❄️ Dormant
Dec 2" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Iosco 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 ~1,760 GDD — county provides 2,272 GDD Good fit

Celeriac Planting Timeline — Iosco County, MI

Celeriac Planting Calendar

Activity When Date Range
Start Indoors April 9 Apr 9 – Apr 23
Transplant Outdoors May 14 May 14 – May 28
Direct Sow April 30 Apr 30 – May 21
Harvest August 27 Aug 27 – Oct 1
Fall Sowing July 25 Jul 25 – Aug 8

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

Month-by-Month Timeline

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

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

142 days in Iosco County

Growing Tips for Celeriac in Iosco County

Direct sow Celeriac outdoors after May 14 in Iosco 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 Iosco County, MI?

Iosco County is in Zone 5b with an average last frost of May 14. Plan your Celeriac planting based on this frost date — see the calendar above for exact timing.

What planting zone is Iosco County, MI?

Iosco County, Michigan is in USDA Hardiness Zone 5b. The average last spring frost is May 14 and first fall frost is October 3.

When should I plant Celeriac in Iosco County, MI?

In Iosco County, MI, plant Celeriac after the last frost (around May 14) and before the first frost (around October 3). Best results when soil holds above 50°F.

What growing zone is Iosco County, MI for Celeriac?

Iosco County sits in USDA Zone 5b. Celeriac grows reliably in zones 3a through 9b, so it's a good fit here.

Can Celeriac grow in Iosco County's climate?

Yes — Celeriac grows well in Iosco County's temperate climate. Iosco County averages a 142-day frost-free season, with last frost around May 14 and first frost around October 3.

🌱

Your Iosco County Garden Planner — Free

A 22-page printable planner built for Iosco 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 Iosco County, MI. Local conditions may vary. Last updated: August 2026.

Sources & credits

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