When to Plant Radicchio in Glenn County, CA
May in Glenn County, California — your action list
May is a pivotal month for Glenn County, California gardens. Focus on these tasks first and you'll set up the rest of the season for success.
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Basket week: radicchio
Don't tug. Use scissors or pruners for clean cuts — torn stems invite disease.
June prep starts now
- 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.
Glenn County, California is in USDA Zone 9b. The average last spring frost is March 6 and the first fall frost is November 28, giving you a growing season of approximately 267 days.
At an elevation of 270 feet, Glenn County receives approximately 27.1 inches of rainfall annually with predominantly loam soil. Summer highs average 88°F, providing good warmth for Radicchio during the growing season.
Glenn County Soil Profile
Soil Type
Loam
Soil pH
6.5-7.9
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 Glenn County
How your county's soil matches Radicchio's growing requirements.
Soil pH
Your soil pH (6.5–7.9) is more alkaline than Radicchio prefers (6.0–7.0). Add sulfur or peat moss to lower pH.
Soil Texture
The loam soil in Glenn County is excellent for Radicchio — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (3.0%). 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 Sep 09 to harvest before frost.
For a dedicated fall crop, sow by Oct 03.
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 | — | 5.6" | 0" | ❄️ Dormant |
| Feb | — | 5.3" | 0" | ❄️ Dormant |
| Mar | 3" | 4.4" | 0" | ✅ Rainfall sufficient |
| Apr | 3" | 2.5" | 0.5" | 💧 Light watering |
| May | 3" | 0.7" | 2.3" | 🚿 Regular watering |
| Jun | 3" | 0.1" | 2.9" | 🚿 Regular watering |
| Jul | 3" | 0" | 3" | 🚿 Regular watering |
| Aug | 3" | 0" | 3" | 🚿 Regular watering |
| Sep | 3" | 0.3" | 2.7" | 🚿 Regular watering |
| Oct | 3" | 1.3" | 1.7" | 🚿 Regular watering |
| Nov | 3" | 2.5" | 0.5" | 💧 Light watering |
| Dec | — | 4.3" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Mar–Nov in Glenn 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 — Glenn County, CA
Radicchio Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 6 | Feb 6 – Feb 20 |
| Transplant Outdoors | March 6 | Mar 6 – Mar 20 |
| Direct Sow | February 13 | Feb 13 – Mar 6 |
| Harvest | May 8 | May 8 – Jun 12 |
| Fall Sowing | October 3 | Oct 3 – Oct 17 |
Plant 0.5" deep · 6" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Start Indoors Direct Sow |
| March | Transplant Outdoors Direct Sow |
| April | — |
| May | Harvest |
| June | Harvest |
| July | — |
| August | — |
| September | — |
| October | Fall Sowing |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.7"/week · 1-2 times/week
📅 Days to Maturity
60–80 days
🧪 Soil pH
Needs 6–7 · Your soil: too_alkaline
🗺️ USDA Zone
Zone 9b
📆 Growing Season
267 days in Glenn County
Growing Tips for Radicchio in Glenn County
Direct sow Radicchio outdoors after March 06 in Glenn 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 Glenn County, CA?
Glenn County is in Zone 9b with an average last frost of March 6. Plan your Radicchio planting based on this frost date — see the calendar above for exact timing.
What planting zone is Glenn County, CA?
Glenn County, California is in USDA Hardiness Zone 9b. The average last spring frost is March 6 and first fall frost is November 28.
Your Glenn County Garden Planner — Free
A 24-page printable planner built for Glenn 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.