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When to Plant Radicchio in Gallatin County, MT

Gallatin County, Montana Zone 5a May

Gallatin County, Montana gardeners: here's your May plan

If you only do a handful of things in the garden this May, make it these. They're sequenced around your zone's frost timing.

Avg. last frost June 8
Avg. first frost September 19
Soil temp (4") 27°F
Watering High
Pest pressure Low
Daylight 14.7 hrs
  1. Seed radicchio outdoors

    Rake a smooth bed, make a shallow furrow, drop seeds at the spacing on the packet, water gently, walk away.

Before June arrives, get these ready
  • Transplants going out: 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.

Gallatin County, Montana is in USDA Zone 5a. The average last spring frost is June 8 and the first fall frost is September 19, giving you a growing season of approximately 103 days.

At an elevation of 8,376 feet, Gallatin County receives approximately 12.4 inches of rainfall annually with predominantly loam soil. Summer highs average 82°F, so choose short-season varieties of Radicchio to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Radicchio successfully. Mulch heavily to conserve soil moisture.

Gallatin County, MT (Zone 5a) Short season
103 days
Last Spring Frost June 8
103 growing days
First Fall Frost September 19
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Gallatin County Soil Profile

Soil Type

Loam

Soil pH

6.2-8.1

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (9 days to spare)
Start indoors: Apr 20 Transplant: May 25 🍅 Harvest: Jul 27 – Aug 31
Recommended (50%) ✓ Fits season (5 days to spare)
Start indoors: May 4 Transplant: Jun 8 🍅 Harvest: Aug 10 – Sep 14
Safe Start (90%) ✓ Fits season (8 days to spare)
Start indoors: May 16 Transplant: Jun 20 🍅 Harvest: Aug 22 – Sep 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 Gallatin County

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

Soil pH

Your soil pH (6.2–8.1) is more alkaline than Radicchio prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

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.

Plant Water Budget

Plant needs
0.7″/week
Rainfall provides
0.5″/week
You supply
0.2″/week
Watering frequency Only during dry spells
Season total 214 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 0.8" 0" ❄️ Dormant
Feb 0.8" 0" ❄️ Dormant
Mar 1.1" 0" ❄️ Dormant
Apr 1.3" 0" ❄️ Dormant
May 1.3" 0" ❄️ Dormant
Jun 3" 0.8" 2.2" 🚿 Regular watering
Jul 3" 1" 2" 🚿 Regular watering
Aug 3" 1.5" 1.5" 🚿 Regular watering
Sep 3" 1" 2" 🚿 Regular watering
Oct 1.1" 0" ❄️ Dormant
Nov 1" 0" ❄️ Dormant
Dec 0.8" 0" ❄️ Dormant

Water needs are for active growing months only (Jun–Sep in Gallatin 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 ~805 GDD — county provides 1,184 GDD Excellent fit

Radicchio Planting Timeline — Gallatin County, MT

Radicchio Planting Calendar

Activity When Date Range
Start Indoors May 4 May 4 – May 18
Transplant Outdoors June 8 Jun 8 – Jun 22
Direct Sow May 25 May 25 – Jun 15
Harvest August 10 Aug 10 – Sep 14
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
April
May Start Indoors Direct Sow
June Transplant Outdoors Direct Sow
July Fall Sowing
August Harvest
September Harvest
October
November
December
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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: too_alkaline

🗺️ USDA Zone

Zone 5a

📆 Growing Season

103 days in Gallatin County

Growing Tips for Radicchio in Gallatin County

Direct sow Radicchio outdoors after June 08 in Gallatin 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 Gallatin County, MT?

Gallatin County is in Zone 5a with an average last frost of June 8. Plan your Radicchio planting based on this frost date — see the calendar above for exact timing.

What planting zone is Gallatin County, MT?

Gallatin County, Montana is in USDA Hardiness Zone 5a. The average last spring frost is June 8 and first fall frost is September 19.

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Your Gallatin County Garden Planner — Free

A 24-page printable planner built for Gallatin 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 Gallatin 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.