When to Plant Celeriac in Josephine County, OR
May to-do list for Josephine County, Oregon
Your Josephine County, Oregon garden is entering a new phase. Here's what's on the schedule for May and why each task matters now.
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Indoor seed-starting week for celeriac
Give them 6–8 weeks indoors before the last frost and you'll transplant into warm soil with seedlings that are already leaping.
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.
Josephine County, Oregon is in USDA Zone 8b. The average last spring frost is April 22 and the first fall frost is October 20, giving you a growing season of approximately 181 days.
At an elevation of 340 feet, Josephine County receives approximately 52.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 90°F, providing good warmth for Celeriac during the growing season. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Celeriac root diseases.
Josephine County Soil Profile
Soil Type
Silt Loam
Soil pH
5.7-6.2
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 Josephine County
How your county's soil matches Celeriac's growing requirements.
Soil pH
Your soil pH (5.7–6.2) is more acidic than Celeriac prefers (6.0–7.0). Add garden lime to raise pH.
Soil Texture
The silt loam soil in Josephine 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
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 | — | 8.4" | 0" | ❄️ Dormant |
| Feb | — | 6.6" | 0" | ❄️ Dormant |
| Mar | — | 6.2" | 0" | ❄️ Dormant |
| Apr | 3.9" | 3.6" | 0.3" | 💧 Light watering |
| May | 3.9" | 2.7" | 1.2" | 💧 Light watering |
| Jun | 3.9" | 2" | 1.9" | 💧 Light watering |
| Jul | 3.9" | 0.8" | 3.1" | 🚿 Regular watering |
| Aug | 3.9" | 0.9" | 3" | 🚿 Regular watering |
| Sep | 3.9" | 1.9" | 2" | 🚿 Regular watering |
| Oct | 3.9" | 4.4" | 0" | ✅ Rainfall sufficient |
| Nov | — | 7.4" | 0" | ❄️ Dormant |
| Dec | — | 8.2" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Josephine 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 — Josephine County, OR
Celeriac Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 18 | Mar 18 – Apr 1 |
| Transplant Outdoors | April 22 | Apr 22 – May 6 |
| Direct Sow | April 8 | Apr 8 – Apr 29 |
| Harvest | August 5 | Aug 5 – Sep 9 |
| Fall Sowing | August 11 | Aug 11 – Aug 25 |
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 |
| June | — |
| July | — |
| August | Fall Sowing Harvest |
| September | Harvest |
| October | — |
| 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: too_acidic
🗺️ USDA Zone
Zone 8b
📆 Growing Season
181 days in Josephine County
Growing Tips for Celeriac in Josephine County
Direct sow Celeriac outdoors after April 22 in Josephine 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 Josephine County, OR?
Josephine County is in Zone 8b with an average last frost of April 22. Plan your Celeriac planting based on this frost date — see the calendar above for exact timing.
What planting zone is Josephine County, OR?
Josephine County, Oregon is in USDA Hardiness Zone 8b. The average last spring frost is April 22 and first fall frost is October 20.
Your Josephine County Garden Planner — Free
A 24-page printable planner built for Josephine County (Zone 8b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.