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When to Plant Marjoram in Jefferson 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.

Jefferson County, Oregon is in USDA Zone 6a. The average last spring frost is June 9 and the first fall frost is September 19, giving you a growing season of approximately 102 days.

At an elevation of 21 feet, Jefferson County receives approximately 36.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 79ยฐF, so choose short-season varieties of Marjoram to ensure they mature before fall.

Jefferson County, OR (Zone 6a) Short season
102 days
Last Spring Frost June 9
102 growing days
First Fall Frost September 19

Jefferson County Soil Profile

Soil Type

Silt Loam

Soil pH

5.3-6.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: Jun 6 🍅 Harvest: Aug 8 – Oct 17
Recommended (50%) ✗ May not fit
Transplant: Jun 16 🍅 Harvest: Aug 18 – Oct 27
Safe Start (90%) ✗ May not fit
Transplant: Jun 29 🍅 Harvest: Aug 31 – Nov 9

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
1.5″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Marjoram needs ~694 GDD — county provides 943 GDD Excellent fit

Marjoram Planting Timeline โ€” Jefferson County, OR

Marjoram Planting Calendar

Activity When Date Range
Transplant Outdoors June 16 Jun 16 โ€“ Jun 30
Harvest August 18 Aug 18 โ€“ Oct 27

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 โ€”
June Transplant Outdoors
July โ€”
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

102 days

Growing Tips for Jefferson 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 Jefferson County, OR?

Jefferson County is in Zone 6a with an average last frost of June 9. Plan your Marjoram planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Jefferson County, OR?

Jefferson County, Oregon is in USDA Hardiness Zone 6a. The average last spring frost is June 9 and first fall frost is September 19.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Jefferson 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 Jefferson County, OR. Local conditions may vary. Last updated: April 2026.