When to Plant Celeriac in Mills County, IA
This month in Mills County, Iowa
Each item below is timed to Mills County, Iowa's frost dates and soil temperatures. Skip nothing, stress about nothing.
-
Indoor seed-starting week for celeriac
A seed-starting mix and a sunny window (or a grow light) are all you need. Keep soil warm — around 70°F — for fast germination.
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.
Mills County, Iowa is in USDA Zone 5b. The average last spring frost is April 26 and the first fall frost is October 7, giving you a growing season of approximately 164 days.
At an elevation of 1,355 feet, Mills County receives approximately 35.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Celeriac during the growing season.
Mills County Soil Profile
Soil Type
Silt Loam
Soil pH
6.3-6.8
Drainage
Well Drained
Plant 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 Mills County
How your county's soil matches Celeriac's growing requirements.
Soil pH
Your soil pH (6.3–6.8) is within Celeriac's preferred range (6.0–7.0).
Soil Texture
The silt loam soil in Mills County is excellent for Celeriac — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Celeriac is a heavy drinker but your soil drains very quickly. Mulch heavily and consider drip irrigation.
Organic Matter
Organic matter is excellent (4.1%) — Celeriac will thrive.
How to Plant Celeriac
Fall planting: Sow 10 weeks before your first frost date for a fall harvest.
Plant Water Budget
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 | — | 1.4" | 0" | ❄️ Dormant |
| Mar | — | 2.5" | 0" | ❄️ Dormant |
| Apr | 3.9" | 3" | 0.9" | 💧 Light watering |
| May | 3.9" | 4.4" | 0" | ✅ Rainfall sufficient |
| Jun | 3.9" | 4.3" | 0" | ✅ Rainfall sufficient |
| Jul | 3.9" | 4.2" | 0" | ✅ Rainfall sufficient |
| Aug | 3.9" | 3.5" | 0.4" | 💧 Light watering |
| Sep | 3.9" | 3.3" | 0.6" | 💧 Light watering |
| Oct | 3.9" | 2.6" | 1.3" | 💧 Light watering |
| Nov | — | 2.3" | 0" | ❄️ Dormant |
| Dec | — | 2.1" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Mills 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 — Mills County, IA
Celeriac Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 22 | Mar 22 – Apr 5 |
| Transplant Outdoors | April 26 | Apr 26 – May 10 |
| Direct Sow | April 12 | Apr 12 – May 3 |
| Harvest | August 9 | Aug 9 – Sep 13 |
| Fall Sowing | July 29 | Jul 29 – Aug 12 |
Plant 1" deep · 15" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Start Indoors Transplant Outdoors Direct Sow |
| May | Transplant Outdoors Direct Sow |
| June | — |
| July | Fall Sowing |
| August | Fall Sowing Harvest |
| September | Harvest |
| 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: ideal
🗺️ USDA Zone
Zone 5b
📆 Growing Season
164 days in Mills County
Growing Tips for Celeriac in Mills County
Direct sow Celeriac outdoors after April 26 in Mills 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
Check more plant combinations with our Companion Planting Checker →
Celeriac in Other Locations
Frequently Asked Questions
When should I plant Celeriac in Mills County, IA?
Mills County is in Zone 5b with an average last frost of April 26. Plan your Celeriac planting based on this frost date — see the calendar above for exact timing.
What planting zone is Mills County, IA?
Mills County, Iowa is in USDA Hardiness Zone 5b. The average last spring frost is April 26 and first fall frost is October 7.
Your Mills County Garden Planner — Free
A 24-page printable planner built for Mills 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.