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When to Plant Celeriac in Macon County, IL

Macon County, Illinois Zone 6a May

May to-do list for Macon County, Illinois

May is a pivotal month for Macon County, Illinois gardens. Focus on these tasks first and you'll set up the rest of the season for success.

Avg. last frost April 13
Avg. first frost October 19
Soil temp (4") 57°F
Watering Moderate
Pest pressure Low
Daylight 14.2 hrs
  1. Start celeriac indoors

    These need a head start before your last frost (April 13). Sow into cells now so you're ready to transplant in a few weeks.

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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.

Macon County, Illinois is in USDA Zone 6a. The average last spring frost is April 13 and the first fall frost is October 19, giving you a growing season of approximately 189 days.

At an elevation of 1,064 feet, Macon County receives approximately 31.3 inches of rainfall annually with predominantly silt loam soil. Summer highs average 86°F, providing good warmth for Celeriac during the growing season.

Macon County, IL (Zone 6a) Moderate season
189 days
Last Spring Frost April 13
189 growing days
First Fall Frost October 19
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Macon County Soil Profile

Soil Type

Silt Loam

Soil pH

6-7.1

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (49 days to spare)
Start indoors: Mar 3 Transplant: Apr 7 🍅 Harvest: Jul 21 – Aug 25
Recommended (50%) ✓ Fits season (49 days to spare)
Start indoors: Mar 9 Transplant: Apr 13 🍅 Harvest: Jul 27 – Aug 31
Safe Start (90%) ✓ Fits season (52 days to spare)
Start indoors: Mar 20 Transplant: Apr 24 🍅 Harvest: Aug 7 – Sep 11

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 Macon County

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

Soil pH

Your soil pH (6.0–7.1) overlaps with Celeriac's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is excellent (4.3%) — 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
0.7″/week
You supply
0.2″/week
Watering frequency Only during dry spells
Season total 344 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 3.9" 2.9" 1" 💧 Light watering
May 3.9" 3.1" 0.8" 💧 Light watering
Jun 3.9" 4.1" 0" ✅ Rainfall sufficient
Jul 3.9" 3.5" 0.4" 💧 Light watering
Aug 3.9" 3.5" 0.4" 💧 Light watering
Sep 3.9" 2.9" 1" 💧 Light watering
Oct 3.9" 2.3" 1.6" 💧 Light watering
Nov 2.4" 0" ❄️ Dormant
Dec 1.6" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Macon 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 ~1,595 GDD — county provides 2,740 GDD Excellent fit

Celeriac Planting Timeline — Macon County, IL

Celeriac Planting Calendar

Activity When Date Range
Start Indoors March 9 Mar 9 – Mar 23
Transplant Outdoors April 13 Apr 13 – Apr 27
Direct Sow March 30 Mar 30 – Apr 20
Harvest July 27 Jul 27 – Aug 31
Fall Sowing August 10 Aug 10 – Aug 24

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

Month-by-Month Timeline

MonthActivities
January
February
March Start Indoors Direct Sow
April Transplant Outdoors Direct Sow
May
June
July Harvest
August Fall Sowing Harvest
September
October
November
December
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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 6a

📆 Growing Season

189 days in Macon County

Growing Tips for Celeriac in Macon County

Direct sow Celeriac outdoors after April 13 in Macon 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 Macon County, IL?

Macon County is in Zone 6a with an average last frost of April 13. Plan your Celeriac planting based on this frost date — see the calendar above for exact timing.

What planting zone is Macon County, IL?

Macon County, Illinois is in USDA Hardiness Zone 6a. The average last spring frost is April 13 and first fall frost is October 19.

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Your Macon County Garden Planner — Free

A 24-page printable planner built for Macon County (Zone 6a). 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 Macon County, IL. 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.