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When to Plant Oregano in Big Horn County, MT

Oregano is a robust perennial herb essential to Italian and Greek cuisine. Its pungent, savory leaves intensify in flavor when dried.

Big Horn County, Montana is in USDA Zone 4b. The average last spring frost is May 13 and the first fall frost is September 30, giving you a growing season of approximately 140 days.

At an elevation of 5,955 feet, Big Horn County receives approximately 22.5 inches of rainfall annually with predominantly loam soil. Summer highs average 83ยฐF, so choose short-season varieties of Oregano to ensure they mature before fall.

Big Horn County, MT (Zone 4b) Short season
140 days
Last Spring Frost May 13
140 growing days
First Fall Frost September 30

Big Horn County Soil Profile

Soil Type

Loam

Soil pH

6.2-7.6

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: May 15 🍅 Harvest: Jul 17 – Sep 25
Recommended (50%) ✓ Fits season (0 days to spare)
Transplant: May 20 🍅 Harvest: Jul 22 – Sep 30
Safe Start (90%) ✗ May not fit
Transplant: Jun 7 🍅 Harvest: Aug 9 – Oct 18

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
0.5″/week
Rainfall provides
0.7″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Drought risk

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

Oregano needs ~919 GDD — county provides 1,715 GDD Excellent fit

Oregano Planting Timeline โ€” Big Horn County, MT

Oregano Planting Calendar

Activity When Date Range
Transplant Outdoors May 20 May 20 โ€“ Jun 3
Harvest July 22 Jul 22 โ€“ Sep 30

Plant 0.5" deep ยท 8" apart ยท Rows 12" apart

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March โ€”
April โ€”
May Transplant Outdoors
June Transplant Outdoors
July Harvest
August Harvest
September Harvest
October โ€”
November โ€”
December โ€”

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Low โ€” drought tolerant

Days to Maturity

60โ€“90 days

Soil pH

6 โ€“ 8

USDA Zone

Zone 4b

Growing Season

140 days

Growing Tips for Big Horn County

Start from seed, cuttings, or divisions. Harvest just before flowering for strongest flavor. Cut plants back to a few inches in spring to encourage vigorous new growth.

Companion Planting

Good Companions

Level Up Your Garden

Frequently Asked Questions

When should I plant Oregano in Big Horn County, MT?

Big Horn County is in Zone 4b with an average last frost of May 13. Plan your Oregano planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Big Horn County, MT?

Big Horn County, Montana is in USDA Hardiness Zone 4b. The average last spring frost is May 13 and first fall frost is September 30.

๐ŸŒฑ

Plan Your Garden with Confidence

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