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When to Plant Thyme in Clackamas County, OR

Thyme is a low-growing perennial herb with tiny, aromatic leaves and a warm, earthy flavor. It is one of the most versatile culinary and medicinal herbs.

Clackamas County, Oregon is in USDA Zone 8a. The average last spring frost is April 14 and the first fall frost is October 28, giving you a growing season of approximately 197 days.

At an elevation of 199 feet, Clackamas County receives approximately 53.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85ยฐF, providing good warmth for Thyme during the growing season. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Thyme root diseases.

Clackamas County, OR (Zone 8a) Moderate season
197 days
Last Spring Frost April 14
197 growing days
First Fall Frost October 28

Clackamas County Soil Profile

Soil Type

Silt Loam

Soil pH

5.7-6.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (57 days to spare)
Transplant: Apr 11 🍅 Harvest: Jun 20 – Aug 22
Recommended (50%) ✓ Fits season (57 days to spare)
Transplant: Apr 21 🍅 Harvest: Jun 30 – Sep 1
Safe Start (90%) ✓ Fits season (61 days to spare)
Transplant: May 14 🍅 Harvest: Jul 23 – Sep 24

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
1.1″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Thyme needs ~1,100 GDD — county provides 2,708 GDD Excellent fit

Thyme Planting Timeline โ€” Clackamas County, OR

Thyme Planting Calendar

Activity When Date Range
Transplant Outdoors April 21 Apr 21 โ€“ May 5
Harvest June 30 Jun 30 โ€“ Sep 1

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

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March โ€”
April Transplant Outdoors
May Transplant Outdoors
June Harvest
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

70โ€“90 days

Soil pH

6 โ€“ 8

USDA Zone

Zone 8a

Growing Season

197 days

Growing Tips for Clackamas County

Start from seed, cuttings, or divisions. Plant in well-drained, lean soil. Prune lightly after flowering. Replace plants every 3-4 years when they become woody.

Companion Planting

Good Companions

Level Up Your Garden

Frequently Asked Questions

When should I plant Thyme in Clackamas County, OR?

Clackamas County is in Zone 8a with an average last frost of April 14. Plan your Thyme planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Clackamas County, OR?

Clackamas County, Oregon is in USDA Hardiness Zone 8a. The average last spring frost is April 14 and first fall frost is October 28.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Clackamas County gardeners in Zone 8a 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 Clackamas County, OR. Local conditions may vary. Last updated: April 2026.