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When to plant Ageratum in Union County County,

Plant Ageratum in Union County County, when soil hits 50°F — usually April 6. Continue planting through April 27 for the spring crop.

When to Plant Ageratum in Union County, KY

Union County, Kentucky Zone 7a June

June in the garden — Union County, Kentucky

We've pulled the most time-sensitive tasks for Union County, Kentucky this June and put them front and centre. Tackle them in order.

Avg. last frost April 6
Avg. first frost October 31
Soil temp (4") 71°F
Watering Low
Pest pressure High
Daylight 14.6 hrs
  1. Harvest ageratum as they ripen

    Don't tug. Use scissors or pruners for clean cuts — torn stems invite disease.

A few tasks this June that'll pay off in July
  • First harvests: ageratum

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Ageratum (Ageratum houstonianum), the floss flower, produces clusters of fluffy, powder-puff blooms in the rare sky-blue and lavender tones difficult to find among warm-season annuals. Compact mounding habit makes it ideal as a front-of-border edging plant. Blooms from early summer through fall with minimal deadheading; heat and humidity tolerant once established.

Union County, Kentucky is in USDA Zone 7a. The average last spring frost is April 6 and the first fall frost is October 31, giving you a growing season of approximately 208 days.

At an elevation of 1,482 feet, Union County receives approximately 48.8 inches of rainfall annually with predominantly silt loam soil. Summer highs average 86°F, providing good warmth for Ageratum during the growing season.

Annual Blooms in Multi-season Pollinator-friendly Good for cutting
Union County, KY (Zone 7a) Long season
208 days
Last Spring Frost April 6
208 growing days
First Fall Frost October 31
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Union County Soil Profile

Soil Type

Silt Loam

Soil pH

5.4-6.6

Drainage

Well Drained

Ageratum Planting Risk Windows

Early Start (70% safe) ✓ Fits season (39 days to spare)
Start indoors: Feb 15 Transplant: Mar 29 🌸 Bloom: May 24 – Sep 13
Recommended (50%) ✓ Fits season (40 days to spare)
Start indoors: Feb 23 Transplant: Apr 6 🌸 Bloom: Jun 1 – Sep 21
Safe Start (90%) ✓ Fits season (47 days to spare)
Start indoors: Mar 6 Transplant: Apr 17 🌸 Bloom: Jun 12 – Oct 2

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 Union County

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

Soil pH

Your soil pH (5.4–6.6) overlaps with Ageratum's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.5%). Annual compost additions will help Ageratum.

How to Plant Ageratum

8"
Between Plants
10"
Between Rows

Succession Planting Ageratum

4
successive plantings in your 208-day season

Sow every 6.9 weeks. Last sowing by Aug 17 to harvest before frost.

Ageratum Water Budget

Plant needs
1.0″/week
Rainfall provides
1.0″/week
You supply
0.0″/week
Watering frequency Only during dry spells
Season total 27 gal / 100 sq ft

Monthly Watering Guide for Ageratum

Ageratum needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Ageratum Needs Rainfall You Supplement Action
Jan 4.1" 0" ❄️ Dormant
Feb 3.5" 0" ❄️ Dormant
Mar 4.6" 0" ❄️ Dormant
Apr 4.3" 4" 0.3" 💧 Light watering
May 4.3" 3.6" 0.7" 💧 Light watering
Jun 4.3" 4.2" 0.1" 💧 Light watering
Jul 4.3" 5.5" 0" ✅ Rainfall sufficient
Aug 4.3" 5" 0" ✅ Rainfall sufficient
Sep 4.3" 4.1" 0.2" 💧 Light watering
Oct 4.3" 2.8" 1.5" 💧 Light watering
Nov 3.7" 0" ❄️ Dormant
Dec 3.9" 0" ❄️ Dormant

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

Ageratum 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.

Ageratum needs ~979 GDD — county provides 3,016 GDD Excellent fit

Ageratum Planting Timeline — Union County, KY

Ageratum Planting Calendar

Activity When Date Range
Start Indoors February 23 Feb 23 – Mar 9
Transplant Outdoors April 6 Apr 6 – Apr 20
Direct Sow April 6 Apr 6 – Apr 27
Bloom June 1 Jun 1 – Sep 21

· 8" apart · Rows 10" apart

Month-by-Month Timeline

MonthActivities
January
February Start Indoors
March Start Indoors
April Transplant Outdoors Direct Sow
May
June Bloom
July Bloom
August Bloom
September Bloom
October
November
December
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Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

60–75 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 7a

📆 Growing Season

208 days in Union County

Growing Tips for Ageratum in Union County

Direct sow Ageratum outdoors after April 06 in Union County when soil has warmed and frost danger has passed.

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

General growing tips

Start seeds indoors 6–8 weeks before last frost — do not cover seed; it needs light to germinate. Can be direct-sown after last frost once soil warms to 60°F. Transplant or thin to proper spacing after frost danger passes. Deadheading isn't strictly required but tidying spent clusters improves appearance. Provide consistent moisture; drought causes premature setting. Avoid deep shade — blooms best in full sun to light afternoon shade.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Ageratum in Union County, KY?

Union County is in Zone 7a with an average last frost of April 6. Plan your Ageratum planting based on this frost date — see the calendar above for exact timing.

What planting zone is Union County, KY?

Union County, Kentucky is in USDA Hardiness Zone 7a. The average last spring frost is April 6 and first fall frost is October 31.

When should I plant Ageratum in Union County, ?

In Union County, , plant Ageratum after the last frost (around April 6) and before the first frost (around October 31). Best results when soil holds above 50°F.

What growing zone is Union County, for Ageratum?

Union County sits in USDA Zone 7a. Ageratum grows reliably in zones 3a through 11b, so it's a good fit here.

Can Ageratum grow in Union County's climate?

Yes — Ageratum grows well in Union County's temperate climate. Union County averages a 208-day frost-free season, with last frost around April 6 and first frost around October 31.

🌱

Your Union County Garden Planner — Free

A 22-page printable planner built for Union County (Zone 7a). 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 Union County, KY. Local conditions may vary. Last updated: June 2026.

Sources & credits

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