Blog

When to Plant Oregano in Carter County, MT

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

Carter County, Montana is in USDA Zone 4a. The average last spring frost is May 15 and the first fall frost is September 22, giving you a growing season of approximately 130 days.

At an elevation of 7,923 feet, Carter County receives approximately 19.8 inches of rainfall annually with predominantly loam soil. Summer highs average 81ยฐF, so choose short-season varieties of Oregano to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Oregano successfully. Mulch heavily to conserve soil moisture.

Carter County, MT (Zone 4a) Short season
130 days
Last Spring Frost May 15
130 growing days
First Fall Frost September 22

Carter County Soil Profile

Soil Type

Loam

Soil pH

6.4-8.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: May 18 🍅 Harvest: Jul 20 – Sep 28
Recommended (50%) ✗ May not fit
Transplant: May 22 🍅 Harvest: Jul 24 – Oct 2
Safe Start (90%) ✗ May not fit
Transplant: Jun 9 🍅 Harvest: Aug 11 – Oct 20

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
0.6″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Drought risk

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

Oregano needs ~806 GDD — county provides 1,397 GDD Excellent fit

Oregano Planting Timeline โ€” Carter County, MT

Oregano Planting Calendar

Activity When Date Range
Transplant Outdoors May 22 May 22 โ€“ Jun 5
Harvest July 24 Jul 24 โ€“ Oct 2

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 Harvest
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 4a

Growing Season

130 days

Growing Tips for Carter 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 Carter County, MT?

Carter County is in Zone 4a with an average last frost of May 15. Plan your Oregano planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Carter County, MT?

Carter County, Montana is in USDA Hardiness Zone 4a. The average last spring frost is May 15 and first fall frost is September 22.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Carter County gardeners in Zone 4a organize planting dates, track what's growing, and never miss a planting window.

Get Your Free Garden Planner →

Free download. Plan your entire garden season in minutes.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Carter County, MT. Local conditions may vary. Last updated: April 2026.