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When to Plant Marjoram in Malheur County, OR

Sweet marjoram is a tender perennial herb with a delicate, sweet oregano-like flavor. It is a cornerstone of Mediterranean cooking and pairs well with meats and vegetables.

Malheur County, Oregon is in USDA Zone 6a. The average last spring frost is May 18 and the first fall frost is September 29, giving you a growing season of approximately 134 days.

At an elevation of 2,676 feet, Malheur County receives approximately 17.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 90ยฐF, providing good warmth for Marjoram during the growing season. With low rainfall, drip irrigation is essential for growing Marjoram successfully. Mulch heavily to conserve soil moisture.

Malheur County, OR (Zone 6a) Short season
134 days
Last Spring Frost May 18
134 growing days
First Fall Frost September 29

Malheur County Soil Profile

Soil Type

Silt Loam

Soil pH

5.4-6.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (1 days to spare)
Transplant: May 8 🍅 Harvest: Jul 10 – Sep 18
Recommended (50%) ✗ May not fit
Transplant: May 25 🍅 Harvest: Jul 27 – Oct 5
Safe Start (90%) ✗ May not fit
Transplant: Jun 19 🍅 Harvest: Aug 21 – Oct 30

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
0.6″/week
You supply
0.8″/week
Watering frequency 2-3 times/week
Season total 896 gal / 100 sq ft
Marjoram needs ~1,312 GDD — county provides 2,345 GDD Excellent fit

Marjoram Planting Timeline โ€” Malheur County, OR

Marjoram Planting Calendar

Activity When Date Range
Transplant Outdoors May 25 May 25 โ€“ Jun 8
Harvest July 27 Jul 27 โ€“ Oct 5

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

Moderate โ€” regular watering

Days to Maturity

60โ€“90 days

Soil pH

6.5 โ€“ 7.5

USDA Zone

Zone 6a

Growing Season

134 days

Growing Tips for Malheur County

Start seeds indoors 6-8 weeks before last frost. Harvest stems just as flower buds appear for peak flavor. In cold climates, grow as an annual or bring containers indoors.

Companion Planting

Good Companions

Level Up Your Garden

Frequently Asked Questions

When should I plant Marjoram in Malheur County, OR?

Malheur County is in Zone 6a with an average last frost of May 18. Plan your Marjoram planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Malheur County, OR?

Malheur County, Oregon is in USDA Hardiness Zone 6a. The average last spring frost is May 18 and first fall frost is September 29.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Malheur County gardeners in Zone 6a 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 Malheur County, OR. Local conditions may vary. Last updated: April 2026.