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When to Plant Yarrow in Spencer County, KY

Spencer County, Kentucky Zone 6b May

May to-do list for Spencer County, Kentucky

May rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Spencer County, Kentucky.

Avg. last frost April 8
Avg. first frost October 29
Soil temp (4") 59°F
Watering Moderate
Pest pressure Low
Daylight 14.1 hrs

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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.

Spencer County, Kentucky is in USDA Zone 6b. The average last spring frost is April 8 and the first fall frost is October 29, giving you a growing season of approximately 204 days.

At an elevation of 2,819 feet, Spencer County receives approximately 40.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 86°F, providing good warmth for Yarrow during the growing season.

Spencer County, KY (Zone 6b) Long season
204 days
Last Spring Frost April 8
204 growing days
First Fall Frost October 29

Spencer County Soil Profile

Soil Type

Silt Loam

Soil pH

5.3-6.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (30 days to spare)
Transplant: Apr 9 🍅 Harvest: Jul 9 – Sep 24
Recommended (50%) ✓ Fits season (29 days to spare)
Transplant: Apr 15 🍅 Harvest: Jul 15 – Sep 30
Safe Start (90%) ✓ Fits season (25 days to spare)
Transplant: May 1 🍅 Harvest: Jul 31 – Oct 16

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.

Soil Compatibility in Spencer County

How your county's soil matches Yarrow's growing requirements.

Soil pH

Your soil pH (5.3–6.7) overlaps with Yarrow's range (5.5–7.0), though not a perfect match.

Soil Texture

The silt loam soil in Spencer County is excellent for Yarrow — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (3.1%). Annual compost additions will help Yarrow.

How to Plant Yarrow

0.5"
Planting Depth
8"
Between Plants
12"
Between Rows

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

Monthly Watering Guide for Yarrow

Yarrow needs approximately 0.5 inches of water per week (2.2" per month). Here's how your county's rainfall compares month by month.

Month Yarrow Needs Rainfall You Supplement Action
Jan 3" 0" ❄️ Dormant
Feb 3.4" 0" ❄️ Dormant
Mar 4.2" 0" ❄️ Dormant
Apr 2.2" 3.2" 0" ✅ Rainfall sufficient
May 2.2" 3.6" 0" ✅ Rainfall sufficient
Jun 2.2" 3.1" 0" ✅ Rainfall sufficient
Jul 2.2" 4.3" 0" ✅ Rainfall sufficient
Aug 2.2" 3.7" 0" ✅ Rainfall sufficient
Sep 2.2" 3.2" 0" ✅ Rainfall sufficient
Oct 2.2" 2.9" 0" ✅ Rainfall sufficient
Nov 2.7" 0" ❄️ Dormant
Dec 3.4" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Spencer County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Yarrow Heat Requirements (GDD)

What are Growing Degree Days (GDD)?

Growing Degree Days measure the total warmth your plants receive during the growing season. Think of it as a "heat bank" — every day above 50°F deposits warmth that helps your plants grow.

Each plant needs a certain amount of accumulated heat to mature. If your county provides more GDD than the plant needs, it's a great fit. If it's close, you may want to choose faster-maturing varieties or start seeds indoors to get a head start.

Yarrow needs ~1,522 GDD — county provides 2,958 GDD Excellent fit

Yarrow Planting Timeline — Spencer County, KY

Yarrow Planting Calendar

Activity When Date Range
Transplant Outdoors April 15 Apr 15 – Apr 29
Harvest July 15 Jul 15 – Sep 30

Plant 0.5" deep · 8" apart · Rows 12" apart

Month-by-Month Timeline

MonthActivities
January
February
March
April Transplant Outdoors
May
June
July Harvest
August Harvest
September Harvest
October
November
December

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.5"/week · Natural rainfall sufficient

📅 Days to Maturity

90–120 days

🧪 Soil pH

Needs 5.5–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 6b

📆 Growing Season

204 days in Spencer County

Growing Tips for Yarrow in Spencer County

Direct sow Yarrow outdoors after April 08 in Spencer County when soil has warmed and frost danger has passed.

Common pests for Yarrow in this region include aphids and slugs. Use row covers early in the season and inspect plants weekly.

General growing tips

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

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Yarrow in Spencer County, KY?

Spencer County is in Zone 6b with an average last frost of April 8. Plan your Yarrow planting based on this frost date — see the calendar above for exact timing.

What planting zone is Spencer County, KY?

Spencer County, Kentucky is in USDA Hardiness Zone 6b. The average last spring frost is April 8 and first fall frost is October 29.

🌱

Your Spencer County Garden Planner — Free

A 24-page printable planner built for Spencer County (Zone 6b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

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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 Spencer County, KY. Local conditions may vary. Last updated: May 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.