When to Plant Radicchio in Butte County, CA
May to-do list for Butte County, California
Welcome to May in Zone 9b. These are the moves that will have the biggest impact on your growing season.
-
Start radicchio under lights
Label every cell. You will absolutely forget which is which otherwise.
Coming up in June — start thinking about
- First harvests: radicchio
Radicchio is an Italian chicory with stunning red and white leaves and a pleasantly bitter flavor. It forms tight heads and is used in salads, grilled, or braised.
Butte County, California is in USDA Zone 9b. The average last spring frost is April 20 and the first fall frost is November 10, giving you a growing season of approximately 204 days.
At an elevation of 144 feet, Butte County receives approximately 44.8 inches of rainfall annually with predominantly loam soil. Summer highs average 90°F, providing good warmth for Radicchio during the growing season.
Butte County Soil Profile
Soil Type
Loam
Soil pH
6.8-7.7
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 Butte County
How your county's soil matches Radicchio's growing requirements.
Soil pH
Your soil pH (6.8–7.7) is more alkaline than Radicchio prefers (6.0–7.0). Add sulfur or peat moss to lower pH.
Soil Texture
The loam soil in Butte County is excellent for Radicchio — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Drainage is adequate for Radicchio.
Organic Matter
Organic matter is moderate (2.5%). Annual compost additions will help Radicchio.
How to Plant Radicchio
Fall planting: Sow 8 weeks before your first frost date for a fall harvest.
Succession Planting Radicchio
Sow every 6.9 weeks. Last sowing by Aug 22 to harvest before frost.
For a dedicated fall crop, sow by Sep 15.
Plant Water Budget
Water stress score is 8/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Radicchio
Radicchio needs approximately 0.7 inches of water per week (3" per month). Here's how your county's rainfall compares month by month.
| Month | Radicchio Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 9.7" | 0" | ❄️ Dormant |
| Feb | — | 9.9" | 0" | ❄️ Dormant |
| Mar | — | 6.9" | 0" | ❄️ Dormant |
| Apr | 3" | 3" | 0" | ✅ Rainfall sufficient |
| May | 3" | 1.1" | 1.9" | 🚿 Regular watering |
| Jun | 3" | 0.2" | 2.8" | 🚿 Regular watering |
| Jul | 3" | 0" | 3" | 🚿 Regular watering |
| Aug | 3" | 0" | 3" | 🚿 Regular watering |
| Sep | 3" | 0.4" | 2.6" | 🚿 Regular watering |
| Oct | 3" | 2.1" | 0.9" | 💧 Light watering |
| Nov | 3" | 3.7" | 0" | ✅ Rainfall sufficient |
| Dec | — | 7.8" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Nov in Butte County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Radicchio 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.
Radicchio Planting Timeline — Butte County, CA
Radicchio Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 23 | Mar 23 – Apr 6 |
| Transplant Outdoors | April 20 | Apr 20 – May 4 |
| Direct Sow | March 30 | Mar 30 – Apr 20 |
| Harvest | June 22 | Jun 22 – Jul 27 |
| Fall Sowing | September 15 | Sep 15 – Sep 29 |
Plant 0.5" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors Direct Sow |
| April | Start Indoors Transplant Outdoors Direct Sow |
| May | Transplant Outdoors |
| June | Harvest |
| July | Harvest |
| August | — |
| September | Fall Sowing |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.7"/week · Natural rainfall sufficient
📅 Days to Maturity
60–80 days
🧪 Soil pH
Needs 6–7 · Your soil: too_alkaline
🗺️ USDA Zone
Zone 9b
📆 Growing Season
204 days in Butte County
Growing Tips for Radicchio in Butte County
Direct sow Radicchio outdoors after April 20 in Butte County when soil has warmed and frost danger has passed.
Common pests for Radicchio in this region include aphids and slugs. Use row covers early in the season and inspect plants weekly.
General growing tips
Start in late summer for fall harvest. The red color develops with cool nights and light frost. Harvest when heads are firm and compact.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Radicchio in Other Locations
Frequently Asked Questions
When should I plant Radicchio in Butte County, CA?
Butte County is in Zone 9b with an average last frost of April 20. Plan your Radicchio planting based on this frost date — see the calendar above for exact timing.
What planting zone is Butte County, CA?
Butte County, California is in USDA Hardiness Zone 9b. The average last spring frost is April 20 and first fall frost is November 10.
Your Butte County Garden Planner — Free
A 24-page printable planner built for Butte County (Zone 9b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.