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When to Plant Broccoli in Ravalli County, MT

Broccoli is a nutrient-dense cool-season crop that produces large central heads followed by smaller side shoots. It is one of the most popular garden vegetables.

Ravalli County, Montana is in USDA Zone 5a. The average last spring frost is May 21 and the first fall frost is September 20, giving you a growing season of approximately 122 days.

At an elevation of 7,813 feet, Ravalli County receives approximately 15.1 inches of rainfall annually with predominantly loam soil. Summer highs average 84ยฐF, so choose short-season varieties of Broccoli to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Broccoli successfully. Mulch heavily to conserve soil moisture.

Ravalli County, MT (Zone 5a) Short season
122 days
Last Spring Frost May 21
122 growing days
First Fall Frost September 20

Ravalli County Soil Profile

Soil Type

Loam

Soil pH

6.5-7.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (18 days to spare)
Start indoors: Apr 7 Transplant: May 12 🍅 Harvest: Jul 14 – Aug 25
Recommended (50%) ✓ Fits season (17 days to spare)
Start indoors: Apr 16 Transplant: May 21 🍅 Harvest: Jul 23 – Sep 3
Safe Start (90%) ✓ Fits season (16 days to spare)
Start indoors: May 5 Transplant: Jun 9 🍅 Harvest: Aug 11 – Sep 22

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.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.5″/week
You supply
0.6″/week
Watering frequency 1-2 times/week
Season total 626 gal / 100 sq ft
Drought risk

Water stress score is 8/10 โ€” consider drought-tolerant varieties and mulching

Broccoli needs ~975 GDD — county provides 1,586 GDD Excellent fit

Broccoli Planting Timeline โ€” Ravalli County, MT

Broccoli Planting Calendar

Activity When Date Range
Start Indoors April 16 Apr 16 โ€“ Apr 30
Transplant Outdoors May 21 May 21 โ€“ Jun 4
Direct Sow May 7 May 7 โ€“ May 28
Fall Sowing July 12 Jul 12 โ€“ Jul 26
Harvest July 23 Jul 23 โ€“ Sep 3

Plant 1" deep ยท 15" apart ยท Rows 24" apart

Month-by-Month Timeline

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

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

60โ€“90 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 5a

Growing Season

122 days

Growing Tips for Ravalli County

Start seeds indoors 6-8 weeks before last frost. Provide consistent moisture to prevent hollow stems. Harvest heads before yellow flowers appear.

Companion Planting

Good Companions

Avoid Planting Near

  • Tomatoes
  • Strawberries

Level Up Your Garden

๐ŸŒพ Save Your Own Broccoli Seeds
Life Cycle Biennial
Pollination Cross-Pollinated (insects)
How to Collect Allow plants to flower 2nd year; collect dry pods.
Storage Store airtight; viable 5 years at 35ยฐF, under 50% humidity.

Isolate 1/2 mile from other brassicas. Biennial โ€” must overwinter roots.

Frequently Asked Questions

When should I plant Broccoli in Ravalli County, MT?

Ravalli County is in Zone 5a with an average last frost of May 21. Plan your Broccoli planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Ravalli County, MT?

Ravalli County, Montana is in USDA Hardiness Zone 5a. The average last spring frost is May 21 and first fall frost is September 20.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Ravalli County gardeners in Zone 5a organize planting dates, track what's growing, and never miss a planting window.

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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 Ravalli County, MT. Local conditions may vary. Last updated: April 2026.