When to plant Celeriac in Simpson,
In Simpson, plant Celeriac in spring between March 24 and April 14, once soil temps hold above 50°F. Simpson's last frost averages April 7, so most warm-season crops establish quickly once soil holds above 60°F. For a fall crop, sow between August 12 and August 26 — roughly 120 days before the first frost on October 21.
When to Plant Celeriac in Simpson, IL
Your June planting checklist for Simpson, IL
June is a pivotal month for Simpson, IL gardens. Focus on these tasks first and you'll set up the rest of the season for success.
To set up a strong July, finish these tasks
- First harvests: celeriac
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.
Simpson, Illinois is in USDA Zone 7a. The average last spring frost is April 7 and the first fall frost is October 21, giving you a growing season of approximately 197 days.
At an elevation of 1,006 feet, Johnson County receives approximately 39.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 90°F, providing good warmth for Celeriac during the growing season.
Simpson Soil Profile
Soil Type
Silt Loam
Soil pH
5.9-7.2
Drainage
Well Drained
Celeriac Planting Risk Windows
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 Simpson
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 Johnson County is excellent for Celeriac — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.8%) — Celeriac will thrive.
How to Plant Celeriac
Fall planting: Sow 10 weeks before your first frost date for a fall harvest.
Celeriac Water Budget
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 | — | 1.6" | 0" | ❄️ Dormant |
| Feb | — | 1.9" | 0" | ❄️ Dormant |
| Mar | — | 2.9" | 0" | ❄️ Dormant |
| Apr | 3.9" | 3.6" | 0.3" | 💧 Light watering |
| May | 3.9" | 4.2" | 0" | ✅ Rainfall sufficient |
| Jun | 3.9" | 4.4" | 0" | ✅ Rainfall sufficient |
| Jul | 3.9" | 4.8" | 0" | ✅ Rainfall sufficient |
| Aug | 3.9" | 4.6" | 0" | ✅ Rainfall sufficient |
| Sep | 3.9" | 3.3" | 0.6" | 💧 Light watering |
| Oct | 3.9" | 3.2" | 0.7" | 💧 Light watering |
| Nov | — | 2.9" | 0" | ❄️ Dormant |
| Dec | — | 2.3" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Johnson 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 Planting Timeline — Simpson, IL
Celeriac Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 3 | Mar 3 – Mar 17 |
| Transplant Outdoors | April 7 | Apr 7 – Apr 21 |
| Direct Sow | March 24 | Mar 24 – Apr 14 |
| Harvest | July 21 | Jul 21 – Aug 25 |
| Fall Sowing | August 12 | Aug 12 – Aug 26 |
Plant 1" deep · 15" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors Direct Sow |
| April | Transplant Outdoors Direct Sow |
| May | — |
| June | — |
| July | Harvest |
| August | Fall Sowing Harvest |
| September | — |
| 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 7a
📆 Growing Season
197 days in Johnson County
Growing Tips for Celeriac in Simpson
Direct sow Celeriac outdoors after April 07 in Johnson 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
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Celeriac in Other Locations
When should I plant Celeriac in Simpson, ?
In Simpson, , plant Celeriac after the last frost (around April 7) and before the first frost (around October 21). Best results when soil holds above 50°F.
What growing zone is Simpson, for Celeriac?
Simpson sits in USDA Zone 7a. Celeriac grows reliably in zones 3a through 9b, so it's a good fit here.
Can Celeriac grow in Simpson's climate?
Yes — Celeriac grows well in Simpson's temperate climate. Simpson averages a 197-day frost-free season, with last frost around April 7 and first frost around October 21.
Your Johnson County Garden Planner — Free
A 22-page printable planner built for Johnson County (Zone 7a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.