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When to Plant Rosemary in Skagit County, WA

Rosemary is an aromatic evergreen shrub with needle-like leaves and a piney, citrus flavor. It is a Mediterranean herb that thrives in warm, dry conditions.

Skagit County, Washington is in USDA Zone 8a. The average last spring frost is April 3 and the first fall frost is October 28, giving you a growing season of approximately 208 days.

At an elevation of 232 feet, Skagit County receives approximately 42.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 90ยฐF, providing good warmth for Rosemary during the growing season.

Skagit County, WA (Zone 8a) Long season
208 days
Last Spring Frost April 3
208 growing days
First Fall Frost October 28

Skagit County Soil Profile

Soil Type

Silt Loam

Soil pH

5.6-6.6

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: Mar 30 🍅 Harvest: Jun 22 – Nov 9
Recommended (50%) ✗ May not fit
Transplant: Apr 10 🍅 Harvest: Jul 3 – Nov 20
Safe Start (90%) ✗ May not fit
Transplant: May 12 🍅 Harvest: Aug 4 – Dec 22

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
Rosemary needs ~2,275 GDD — county provides 3,640 GDD Excellent fit

Rosemary Planting Timeline โ€” Skagit County, WA

Rosemary Planting Calendar

Activity When Date Range
Transplant Outdoors April 10 Apr 10 โ€“ Apr 24
Harvest July 3 Jul 3 โ€“ Nov 20

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 โ€”
July Harvest
August Harvest
September Harvest
October Harvest
November Harvest
December โ€”

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Low โ€” drought tolerant

Days to Maturity

80โ€“180 days

Soil pH

6 โ€“ 7.5

USDA Zone

Zone 8a

Growing Season

208 days

Growing Tips for Skagit County

Grow in well-drained soil and avoid overwatering. In cold climates, grow in containers and bring indoors for winter. Propagate from stem cuttings for faster results than seed.

Companion Planting

Good Companions

Level Up Your Garden

Frequently Asked Questions

When should I plant Rosemary in Skagit County, WA?

Skagit County is in Zone 8a with an average last frost of April 3. Plan your Rosemary planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Skagit County, WA?

Skagit County, Washington is in USDA Hardiness Zone 8a. The average last spring frost is April 3 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 Skagit 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 Skagit County, WA. Local conditions may vary. Last updated: April 2026.