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When to Plant Yarrow in Gem County, ID

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.

Gem County, Idaho is in USDA Zone 6a. The average last spring frost is May 9 and the first fall frost is October 1, giving you a growing season of approximately 145 days.

At an elevation of 6,100 feet, Gem County receives approximately 16 inches of rainfall annually with predominantly loam soil. Summer highs average 87ยฐF, 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.

Gem County, ID (Zone 6a) Short season
145 days
Last Spring Frost May 9
145 growing days
First Fall Frost October 1

Gem County Soil Profile

Soil Type

Loam

Soil pH

6.7-7.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: May 8 🍅 Harvest: Aug 7 – Oct 23
Recommended (50%) ✗ May not fit
Transplant: May 16 🍅 Harvest: Aug 15 – Oct 31
Safe Start (90%) ✗ May not fit
Transplant: Jun 14 🍅 Harvest: Sep 13 – Nov 29

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
You supply
0.0″/week
Watering frequency Only during dry spells
Season total 57 gal / 100 sq ft
Drought risk

Water stress score is 8/10 โ€” consider drought-tolerant varieties and mulching

Yarrow needs ~1,601 GDD — county provides 2,211 GDD Excellent fit

Yarrow Planting Timeline โ€” Gem County, ID

Yarrow Planting Calendar

Activity When Date Range
Transplant Outdoors May 16 May 16 โ€“ May 30
Harvest August 15 Aug 15 โ€“ Oct 31

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 6a

Growing Season

145 days

Growing Tips for Gem 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 Gem County, ID?

Gem County is in Zone 6a with an average last frost of May 9. Plan your Yarrow planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Gem County, ID?

Gem County, Idaho is in USDA Hardiness Zone 6a. The average last spring frost is May 9 and first fall frost is October 1.

๐ŸŒฑ

Plan Your Garden with Confidence

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