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When to Plant Yarrow in Grays Harbor County, WA

Yarrow is a drought-tolerant perennial herb with feathery foliage and flat-topped flower clusters in white, yellow, pink, or red. It attracts beneficial insects and is used in herbal medicine.

Grays Harbor County, Washington is in USDA Zone 8a. The average last spring frost is April 27 and the first fall frost is October 23, giving you a growing season of approximately 179 days.

At an elevation of 65 feet, Grays Harbor County receives approximately 39.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 88ยฐF, providing good warmth for Yarrow during the growing season.

Grays Harbor County, WA (Zone 8a) Moderate season
179 days
Last Spring Frost April 27
179 growing days
First Fall Frost October 23

Grays Harbor County Soil Profile

Soil Type

Silt Loam

Soil pH

5.5-6.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (5 days to spare)
Transplant: Apr 21 🍅 Harvest: Jul 21 – Oct 6
Recommended (50%) ✓ Fits season (4 days to spare)
Transplant: May 4 🍅 Harvest: Aug 3 – Oct 19
Safe Start (90%) ✓ Fits season (18 days to spare)
Transplant: May 19 🍅 Harvest: Aug 18 – Nov 3

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
Yarrow needs ~1,680 GDD — county provides 2,864 GDD Excellent fit

Yarrow Planting Timeline โ€” Grays Harbor County, WA

Yarrow Planting Calendar

Activity When Date Range
Transplant Outdoors May 4 May 4 โ€“ May 18
Harvest August 3 Aug 3 โ€“ Oct 19

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

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Low โ€” drought tolerant

Days to Maturity

90โ€“120 days

Soil pH

5.5 โ€“ 7

USDA Zone

Zone 8a

Growing Season

179 days

Growing Tips for Grays Harbor County

Direct sow or start from divisions. Yarrow thrives in poor soil and is very drought-tolerant. Deadhead to encourage reblooming. Divide clumps every 3 years.

Companion Planting

Good Companions

Level Up Your Garden

Frequently Asked Questions

When should I plant Yarrow in Grays Harbor County, WA?

Grays Harbor County is in Zone 8a with an average last frost of April 27. Plan your Yarrow planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Grays Harbor County, WA?

Grays Harbor County, Washington is in USDA Hardiness Zone 8a. The average last spring frost is April 27 and first fall frost is October 23.

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Plan Your Garden with Confidence

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