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When to Plant Radicchio in Inyo County, CA

Inyo County, California Zone 8b May

May in Inyo County, California — your action list

A quick May briefing for Inyo County, California gardeners — what's urgent, what's next, and what can wait.

Avg. last frost January 15
Avg. first frost December 10
Soil temp (4") 57°F
Watering Critical
Pest pressure Moderate
Daylight 13.9 hrs

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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.

Inyo County, California is in USDA Zone 8b. The average last spring frost is January 15 and the first fall frost is December 10, giving you a growing season of approximately 329 days.

At an elevation of 4,562 feet, Inyo County receives approximately 16.4 inches of rainfall annually with predominantly loam soil. Summer highs average 88°F, providing good warmth for Radicchio during the growing season. With low rainfall, drip irrigation is essential for growing Radicchio successfully. Mulch heavily to conserve soil moisture.

Inyo County, CA (Zone 8b) Year-round
329 days
Last Spring Frost January 15
329 growing days
First Fall Frost December 10

Inyo County Soil Profile

Soil Type

Loam

Soil pH

6-7.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (234 days to spare)
Start indoors: Dec 3 Transplant: Jan 7 🍅 Harvest: Mar 11 – Apr 15
Recommended (50%) ✓ Fits season (231 days to spare)
Start indoors: Dec 11 Transplant: Jan 15 🍅 Harvest: Mar 19 – Apr 23
Safe Start (90%) ✓ Fits season (217 days to spare)
Start indoors: Jan 5 Transplant: Feb 9 🍅 Harvest: Apr 13 – May 18

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 Inyo County

How your county's soil matches Radicchio's growing requirements.

Soil pH

Your soil pH (6.0–7.8) overlaps with Radicchio's range (6.0–7.0), though not a perfect match.

Soil Texture

The loam soil in Inyo County is excellent for Radicchio — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (2.2%). Annual compost additions will help Radicchio.

How to Plant Radicchio

0.5"
Planting Depth
6"
Between Plants
12"
Between Rows

Fall planting: Sow 10 weeks before your first frost date for a fall harvest.

Succession Planting Radicchio

6
successive plantings in your 329-day season

Sow every 6.9 weeks. Last sowing by Sep 21 to harvest before frost.

For a dedicated fall crop, sow by Oct 01.

Plant Water Budget

Plant needs
0.7″/week
Rainfall provides
0.2″/week
You supply
0.6″/week
Watering frequency 1-2 times/week
Season total 1,731 gal / 100 sq ft
Drought risk

Water stress score is 10/10 — 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 3" 3.3" 0" ✅ Rainfall sufficient
Feb 3" 3.4" 0" ✅ Rainfall sufficient
Mar 3" 2.5" 0.5" 💧 Light watering
Apr 3" 1.3" 1.7" 🚿 Regular watering
May 3" 0.5" 2.5" 🚿 Regular watering
Jun 3" 0.1" 2.9" 🚿 Regular watering
Jul 3" 0" 3" 🚿 Regular watering
Aug 3" 0" 3" 🚿 Regular watering
Sep 3" 0.2" 2.8" 🚿 Regular watering
Oct 3" 0.6" 2.4" 🚿 Regular watering
Nov 3" 1.7" 1.3" 💧 Light watering
Dec 3" 2.8" 0.2" 💧 Light watering

Water needs are for active growing months only (Jan–Dec in Inyo 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 needs ~1,120 GDD — county provides 5,280 GDD Excellent fit

Radicchio Planting Timeline — Inyo County, CA

Radicchio Planting Calendar

Activity When Date Range
Start Indoors December 11 Dec 11 – Dec 25
Transplant Outdoors January 15 Jan 15 – Jan 29
Direct Sow January 1 Jan 1 – Jan 22
Harvest March 19 Mar 19 – Apr 23
Fall Sowing October 1 Oct 1 – Oct 15

Plant 0.5" deep · 6" apart · Rows 12" apart

Month-by-Month Timeline

MonthActivities
January Transplant Outdoors Direct Sow
February
March Harvest
April Harvest
May
June
July
August
September
October Fall Sowing
November
December Start Indoors

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: acceptable

🗺️ USDA Zone

Zone 8b

📆 Growing Season

329 days in Inyo County

Growing Tips for Radicchio in Inyo County

Direct sow Radicchio outdoors after January 15 in Inyo 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

  • Fennel

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Radicchio in Inyo County, CA?

Inyo County is in Zone 8b with an average last frost of January 15. Plan your Radicchio planting based on this frost date — see the calendar above for exact timing.

What planting zone is Inyo County, CA?

Inyo County, California is in USDA Hardiness Zone 8b. The average last spring frost is January 15 and first fall frost is December 10.

🌱

Your Inyo County Garden Planner — Free

A 24-page printable planner built for Inyo 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.

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Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Inyo County, CA. Local conditions may vary. Last updated: May 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.