Blog

When to Plant Radicchio in Oconto County, WI

Oconto County, Wisconsin Zone 5a May

Oconto County, Wisconsin gardeners: here's your May plan

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

Avg. last frost May 9
Avg. first frost October 4
Soil temp (4") 54°F
Watering Low
Pest pressure Low
Daylight 14.7 hrs
  1. Plant out radicchio

    Bring a watering can to the bed. Each transplant gets a drink the moment it's in the ground, not ten minutes later.

Before June arrives, get these ready
  • Starting indoors: radicchio

Instant PDF download. No spam, unsubscribe any time.

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.

Oconto County, Wisconsin is in USDA Zone 5a. The average last spring frost is May 9 and the first fall frost is October 4, giving you a growing season of approximately 148 days.

At an elevation of 794 feet, Oconto County receives approximately 37.6 inches of rainfall annually with predominantly silt loam soil. Summer highs average 80°F, so choose short-season varieties of Radicchio to ensure they mature before fall.

Oconto County, WI (Zone 5a) Short season
148 days
Last Spring Frost May 9
148 growing days
First Fall Frost October 4

Oconto County Soil Profile

Soil Type

Silt Loam

Soil pH

6-7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (51 days to spare)
Start indoors: Mar 29 Transplant: May 3 🍅 Harvest: Jul 5 – Aug 9
Recommended (50%) ✓ Fits season (50 days to spare)
Start indoors: Apr 4 Transplant: May 9 🍅 Harvest: Jul 11 – Aug 15
Safe Start (90%) ✓ Fits season (49 days to spare)
Start indoors: Apr 21 Transplant: May 26 🍅 Harvest: Jul 28 – Sep 1

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 Oconto County

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

Soil pH

Your soil pH (6.0–7.0) is within Radicchio's preferred range (6.0–7.0).

Soil Texture

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

Organic Matter

Organic matter is excellent (4.7%) — Radicchio will thrive.

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

2
successive plantings in your 148-day season

Sow every 6.9 weeks. Last sowing by Jul 16 to harvest before frost.

For a dedicated fall crop, sow by Jul 26.

Plant Water Budget

Plant needs
0.7″/week
Rainfall provides
1.1″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — 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 1.6" 0" ❄️ Dormant
Feb 1.9" 0" ❄️ Dormant
Mar 2.4" 0" ❄️ Dormant
Apr 3.3" 0" ❄️ Dormant
May 3" 4.1" 0" ✅ Rainfall sufficient
Jun 3" 4.7" 0" ✅ Rainfall sufficient
Jul 3" 4.6" 0" ✅ Rainfall sufficient
Aug 3" 4.1" 0" ✅ Rainfall sufficient
Sep 3" 3.3" 0" ✅ Rainfall sufficient
Oct 3" 2.7" 0.3" 💧 Light watering
Nov 2.8" 0" ❄️ Dormant
Dec 2" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Oconto 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 ~700 GDD — county provides 1,480 GDD Excellent fit

Radicchio Planting Timeline — Oconto County, WI

Radicchio Planting Calendar

Activity When Date Range
Start Indoors April 4 Apr 4 – Apr 18
Transplant Outdoors May 9 May 9 – May 23
Direct Sow April 25 Apr 25 – May 16
Harvest July 11 Jul 11 – Aug 15
Fall Sowing July 26 Jul 26 – Aug 9

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

Month-by-Month Timeline

MonthActivities
January
February
March
April Start Indoors Direct Sow
May Transplant Outdoors Direct Sow
June
July Fall Sowing Harvest
August Fall Sowing Harvest
September
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: ideal

🗺️ USDA Zone

Zone 5a

📆 Growing Season

148 days in Oconto County

Growing Tips for Radicchio in Oconto County

Direct sow Radicchio outdoors after May 09 in Oconto 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 Oconto County, WI?

Oconto County is in Zone 5a with an average last frost of May 9. Plan your Radicchio planting based on this frost date — see the calendar above for exact timing.

What planting zone is Oconto County, WI?

Oconto County, Wisconsin is in USDA Hardiness Zone 5a. The average last spring frost is May 9 and first fall frost is October 4.

🌱

Your Oconto County Garden Planner — Free

A 24-page printable planner built for Oconto County (Zone 5a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

Instant PDF download. No spam, unsubscribe any time.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Oconto County, WI. 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.