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When to Plant Scallions in Beaverhead County, MT

Scallions (green onions) are mild-flavored alliums harvested for their slender green tops and white bases. They are quick-growing and perfect for succession planting.

Beaverhead County, Montana is in USDA Zone 4a. The average last spring frost is June 10 and the first fall frost is September 12, giving you a growing season of approximately 94 days.

At an elevation of 7,645 feet, Beaverhead County receives approximately 15.7 inches of rainfall annually with predominantly loam soil. Summer highs average 80ยฐF, so choose short-season varieties of Scallions to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Scallions successfully. Mulch heavily to conserve soil moisture.

Beaverhead County, MT (Zone 4a) Very short season
94 days
Last Spring Frost June 10
94 growing days
First Fall Frost September 12

Beaverhead County Soil Profile

Soil Type

Loam

Soil pH

6.8-7.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (14 days to spare)
Start indoors: Apr 19 Transplant: May 31 🍅 Harvest: Jul 26 – Aug 23
Recommended (50%) ✓ Fits season (10 days to spare)
Start indoors: Apr 29 Transplant: Jun 10 🍅 Harvest: Aug 5 – Sep 2
Safe Start (90%) ✓ Fits season (14 days to spare)
Start indoors: May 11 Transplant: Jun 22 🍅 Harvest: Aug 17 – Sep 14

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
0.7″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 300 gal / 100 sq ft
Drought risk

Water stress score is 6/10 โ€” consider drought-tolerant varieties and mulching

Scallions needs ~600 GDD — county provides 940 GDD Excellent fit

Scallions Planting Timeline โ€” Beaverhead County, MT

Scallions Planting Calendar

Activity When Date Range
Start Indoors April 29 Apr 29 โ€“ May 13
Transplant Outdoors June 10 Jun 10 โ€“ Jun 24
Direct Sow June 3 Jun 3 โ€“ Jun 24
Fall Sowing June 20 Jun 20 โ€“ Jul 4
Harvest August 5 Aug 5 โ€“ Sep 2

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

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March โ€”
April Start Indoors
May Start Indoors
June Transplant Outdoors Direct Sow Fall Sowing
July Fall Sowing
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

50โ€“70 days

Soil pH

6 โ€“ 7

USDA Zone

Zone 4a

Growing Season

94 days

Growing Tips for Beaverhead County

Direct sow every 3 weeks for continuous harvest. Thin to 1 inch apart or grow in clusters. Harvest when pencil-thick by pulling or cutting at soil level.

Companion Planting

Good Companions

Avoid Planting Near

  • Peas
  • Green Beans

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Frequently Asked Questions

When should I plant Scallions in Beaverhead County, MT?

Beaverhead County is in Zone 4a with an average last frost of June 10. Plan your Scallions planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Beaverhead County, MT?

Beaverhead County, Montana is in USDA Hardiness Zone 4a. The average last spring frost is June 10 and first fall frost is September 12.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Beaverhead County gardeners in Zone 4a 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 Beaverhead County, MT. Local conditions may vary. Last updated: April 2026.