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When to Plant Yarrow in Yakima 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.

Yakima County, Washington is in USDA Zone 6b. The average last spring frost is May 6 and the first fall frost is October 3, giving you a growing season of approximately 150 days.

At an elevation of 3,150 feet, Yakima County receives approximately 18 inches of rainfall annually with predominantly silt loam soil. Summer highs average 86ยฐF, providing good warmth for Yarrow during the growing season. With low rainfall, drip irrigation is essential for growing Yarrow successfully. Mulch heavily to conserve soil moisture.

Yakima County, WA (Zone 6b) Moderate season
150 days
Last Spring Frost May 6
150 growing days
First Fall Frost October 3

Yakima County Soil Profile

Soil Type

Silt Loam

Soil pH

5.5-6.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: May 7 🍅 Harvest: Aug 6 – Oct 22
Recommended (50%) ✗ May not fit
Transplant: May 13 🍅 Harvest: Aug 12 – Oct 28
Safe Start (90%) ✗ May not fit
Transplant: Jun 2 🍅 Harvest: Sep 1 – Nov 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
0.5″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Yarrow needs ~1,522 GDD — county provides 2,175 GDD Excellent fit

Yarrow Planting Timeline โ€” Yakima County, WA

Yarrow Planting Calendar

Activity When Date Range
Transplant Outdoors May 13 May 13 โ€“ May 27
Harvest August 12 Aug 12 โ€“ Oct 28

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 6b

Growing Season

150 days

Growing Tips for Yakima 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 Yakima County, WA?

Yakima County is in Zone 6b with an average last frost of May 6. Plan your Yarrow planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Yakima County, WA?

Yakima County, Washington is in USDA Hardiness Zone 6b. The average last spring frost is May 6 and first fall frost is October 3.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Yakima County gardeners in Zone 6b 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 Yakima County, WA. Local conditions may vary. Last updated: April 2026.