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When to Plant Thyme in Island County, WA

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.

Island County, Washington is in USDA Zone 8a. The average last spring frost is March 30 and the first fall frost is November 3, giving you a growing season of approximately 218 days.

At an elevation of 9 feet, Island County receives approximately 45.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85ยฐF, providing good warmth for Thyme during the growing season.

Island County, WA (Zone 8a) Long season
218 days
Last Spring Frost March 30
218 growing days
First Fall Frost November 3

Island County Soil Profile

Soil Type

Silt Loam

Soil pH

5.6-6.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (81 days to spare)
Transplant: Mar 29 🍅 Harvest: Jun 7 – Aug 9
Recommended (50%) ✓ Fits season (78 days to spare)
Transplant: Apr 6 🍅 Harvest: Jun 15 – Aug 17
Safe Start (90%) ✓ Fits season (68 days to spare)
Transplant: May 7 🍅 Harvest: Jul 16 – Sep 17

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
0.9″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Thyme needs ~1,100 GDD — county provides 2,997 GDD Excellent fit

Thyme Planting Timeline โ€” Island County, WA

Thyme Planting Calendar

Activity When Date Range
Transplant Outdoors April 6 Apr 6 โ€“ Apr 20
Harvest June 15 Jun 15 โ€“ Aug 17

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 โ€”
June Harvest
July Harvest
August Harvest
September โ€”
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

218 days

Growing Tips for Island 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 Island County, WA?

Island County is in Zone 8a with an average last frost of March 30. Plan your Thyme planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Island County, WA?

Island County, Washington is in USDA Hardiness Zone 8a. The average last spring frost is March 30 and first fall frost is November 3.

๐ŸŒฑ

Plan Your Garden with Confidence

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