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When to Plant Radicchio in Stanley County, SD

Stanley County, South Dakota Zone 4b May

Your May game plan for Stanley County, South Dakota

A quick May briefing for Stanley County, South Dakota gardeners — what's urgent, what's next, and what can wait.

Avg. last frost May 10
Avg. first frost October 3
Soil temp (4") 54°F
Watering Moderate
Pest pressure Low
Daylight 14.6 hrs
  1. Move radicchio into the garden

    Your last frost (May 10) has passed. These warm-season crops can handle outdoor soil now.

  2. Direct-sow radicchio

    Keep the top inch of soil moist until germination — a gentle morning watering for 5–7 days does the job.

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

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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.

Stanley County, South Dakota is in USDA Zone 4b. The average last spring frost is May 10 and the first fall frost is October 3, giving you a growing season of approximately 146 days.

At an elevation of 908 feet, Stanley County receives approximately 29.5 inches of rainfall annually with predominantly loam soil. Summer highs average 83°F, so choose short-season varieties of Radicchio to ensure they mature before fall.

Stanley County, SD (Zone 4b) Short season
146 days
Last Spring Frost May 10
146 growing days
First Fall Frost October 3

Stanley County Soil Profile

Soil Type

Loam

Soil pH

6.6-7.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (49 days to spare)
Start indoors: Mar 23 Transplant: May 4 🍅 Harvest: Jul 6 – Aug 10
Recommended (50%) ✓ Fits season (48 days to spare)
Start indoors: Mar 29 Transplant: May 10 🍅 Harvest: Jul 12 – Aug 16
Safe Start (90%) ✓ Fits season (53 days to spare)
Start indoors: Apr 8 Transplant: May 20 🍅 Harvest: Jul 22 – Aug 26

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 Stanley County

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

Soil pH

Your soil pH (6.6–7.2) overlaps with Radicchio's range (6.0–7.0), though not a perfect match.

Soil Texture

The loam soil in Stanley 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 (3.9%). Annual compost additions will help Radicchio.

How to Plant Radicchio

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

Fall planting: Sow 12 weeks before your first frost date for a fall harvest.

Succession Planting Radicchio

2
successive plantings in your 146-day season

Sow every 6.9 weeks. Last sowing by Jul 15 to harvest before frost.

For a dedicated fall crop, sow by Jul 11.

Plant Water Budget

Plant needs
0.7″/week
Rainfall provides
0.9″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 96 gal / 100 sq ft
Drought risk

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 2.2" 0" ❄️ Dormant
Feb 2" 0" ❄️ Dormant
Mar 3" 0" ❄️ Dormant
Apr 2.7" 0" ❄️ Dormant
May 3" 3.4" 0" ✅ Rainfall sufficient
Jun 3" 1.8" 1.2" 💧 Light watering
Jul 3" 2.5" 0.5" 💧 Light watering
Aug 3" 3.1" 0" ✅ Rainfall sufficient
Sep 3" 2.5" 0.5" 💧 Light watering
Oct 3" 2.3" 0.7" 💧 Light watering
Nov 2.2" 0" ❄️ Dormant
Dec 1.8" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Stanley 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 ~858 GDD — county provides 1,788 GDD Excellent fit

Radicchio Planting Timeline — Stanley County, SD

Radicchio Planting Calendar

Activity When Date Range
Start Indoors March 29 Mar 29 – Apr 12
Transplant Outdoors May 10 May 10 – May 24
Direct Sow May 3 May 3 – May 24
Harvest July 12 Jul 12 – Aug 16
Fall Sowing July 11 Jul 11 – Jul 25

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.7"/week · Only during dry spells

📅 Days to Maturity

60–80 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 4b

📆 Growing Season

146 days in Stanley County

Growing Tips for Radicchio in Stanley County

Direct sow Radicchio outdoors after May 10 in Stanley 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 Stanley County, SD?

Stanley County is in Zone 4b with an average last frost of May 10. Plan your Radicchio planting based on this frost date — see the calendar above for exact timing.

What planting zone is Stanley County, SD?

Stanley County, South Dakota is in USDA Hardiness Zone 4b. The average last spring frost is May 10 and first fall frost is October 3.

🌱

Your Stanley County Garden Planner — Free

A 24-page printable planner built for Stanley County (Zone 4b). 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 Stanley County, SD. 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.