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When to Plant Yarrow in Greene County, IL

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.

Greene County, Illinois is in USDA Zone 5b. The average last spring frost is April 13 and the first fall frost is October 21, giving you a growing season of approximately 191 days.

At an elevation of 1,248 feet, Greene County receives approximately 37 inches of rainfall annually with predominantly silt loam soil. Summer highs average 86ยฐF, providing good warmth for Yarrow during the growing season.

Greene County, IL (Zone 5b) Moderate season
191 days
Last Spring Frost April 13
191 growing days
First Fall Frost October 21

Greene County Soil Profile

Soil Type

Silt Loam

Soil pH

6.1-6.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (15 days to spare)
Transplant: Apr 14 🍅 Harvest: Jul 14 – Sep 29
Recommended (50%) ✓ Fits season (16 days to spare)
Transplant: Apr 20 🍅 Harvest: Jul 20 – Oct 5
Safe Start (90%) ✓ Fits season (15 days to spare)
Transplant: May 2 🍅 Harvest: Aug 1 – Oct 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
0.8″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Drought risk

Water stress score is 6/10 โ€” consider drought-tolerant varieties and mulching

Yarrow needs ~1,522 GDD — county provides 2,769 GDD Excellent fit

Yarrow Planting Timeline โ€” Greene County, IL

Yarrow Planting Calendar

Activity When Date Range
Transplant Outdoors April 20 Apr 20 โ€“ May 4
Harvest July 20 Jul 20 โ€“ Oct 5

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 Transplant Outdoors
June โ€”
July Harvest
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 5b

Growing Season

191 days

Growing Tips for Greene 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 Greene County, IL?

Greene County is in Zone 5b with an average last frost of April 13. Plan your Yarrow planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Greene County, IL?

Greene County, Illinois is in USDA Hardiness Zone 5b. The average last spring frost is April 13 and first fall frost is October 21.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Greene County gardeners in Zone 5b 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 Greene County, IL. Local conditions may vary. Last updated: April 2026.