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When to Plant Radicchio in Yellowstone County, MT

Yellowstone County, Montana Zone 5a May

Top priorities for Yellowstone County, Montana gardeners in May

We've pulled the most time-sensitive tasks for Yellowstone County, Montana this May and put them front and centre. Tackle them in order.

Avg. last frost May 9
Avg. first frost October 3
Soil temp (4") 33°F
Watering High
Pest pressure Low
Daylight 14.7 hrs
  1. Get radicchio in the ground

    Water the tray well an hour before you transplant. Roots slide out cleanly and settle in faster.

June prep starts now
  • 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.

Yellowstone County, Montana is in USDA Zone 5a. The average last spring frost is May 9 and the first fall frost is October 3, giving you a growing season of approximately 147 days.

At an elevation of 7,432 feet, Yellowstone County receives approximately 21.1 inches of rainfall annually with predominantly loam soil. Summer highs average 80°F, so choose short-season varieties of Radicchio to ensure they mature before fall.

Yellowstone County, MT (Zone 5a) Short season
147 days
Last Spring Frost May 9
147 growing days
First Fall Frost October 3
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Yellowstone County Soil Profile

Soil Type

Loam

Soil pH

6.2-8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (43 days to spare)
Start indoors: Mar 30 Transplant: May 4 🍅 Harvest: Jul 6 – Aug 10
Recommended (50%) ✓ Fits season (49 days to spare)
Start indoors: Apr 4 Transplant: May 9 🍅 Harvest: Jul 11 – Aug 15
Safe Start (90%) ✓ Fits season (51 days to spare)
Start indoors: Apr 17 Transplant: May 22 🍅 Harvest: Jul 24 – Aug 28

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 Yellowstone County

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

Soil pH

Your soil pH (6.2–8.0) is more alkaline than Radicchio prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

The loam soil in Yellowstone 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 (2.4%). 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

2
successive plantings in your 147-day season

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

For a dedicated fall crop, sow by Jul 25.

Plant Water Budget

Plant needs
0.7″/week
Rainfall provides
0.6″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 482 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 1.3" 0" ❄️ Dormant
Feb 1.2" 0" ❄️ Dormant
Mar 1.9" 0" ❄️ Dormant
Apr 1.9" 0" ❄️ Dormant
May 3" 2.7" 0.3" 💧 Light watering
Jun 3" 1.7" 1.3" 💧 Light watering
Jul 3" 1.7" 1.3" 💧 Light watering
Aug 3" 2.5" 0.5" 💧 Light watering
Sep 3" 1.7" 1.3" 💧 Light watering
Oct 3" 1.8" 1.2" 💧 Light watering
Nov 1.6" 0" ❄️ Dormant
Dec 1.2" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Yellowstone 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 1,470 GDD Excellent fit

Radicchio Planting Timeline — Yellowstone County, MT

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 25 Jul 25 – Aug 8

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
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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 5a

📆 Growing Season

147 days in Yellowstone County

Growing Tips for Radicchio in Yellowstone County

Direct sow Radicchio outdoors after May 09 in Yellowstone 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 Yellowstone County, MT?

Yellowstone 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 Yellowstone County, MT?

Yellowstone County, Montana is in USDA Hardiness Zone 5a. The average last spring frost is May 9 and first fall frost is October 3.

🌱

Your Yellowstone County Garden Planner — Free

A 24-page printable planner built for Yellowstone 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.

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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 Yellowstone County, MT. 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.