Blog

When to plant Ageratum in Clinton County, IL

For Ageratum in Clinton County, the safe spring window opens around April 10 and closes around May 1. Last expected frost is April 10, first fall frost October 19, giving a 192-day growing season.

When to Plant Ageratum in Clinton County, IL

Clinton County, Illinois Zone 6b July

Clinton County, Illinois gardeners: here's your July plan

Each item below is timed to Clinton County, Illinois's frost dates and soil temperatures. Skip nothing, stress about nothing.

Avg. last frost April 10
Avg. first frost October 19
Soil temp (4") 82°F
Watering Low
Pest pressure High
Daylight 14.4 hrs
  1. Bring in the ageratum

    The more you pick, the more the plant produces. Letting fruit overripen tells the plant it's time to stop.

To set up a strong August, finish these tasks
  • First harvests: ageratum

Instant PDF download. No spam, unsubscribe any time.

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.

Clinton County, Illinois is in USDA Zone 6b. The average last spring frost is April 10 and the first fall frost is October 19, giving you a growing season of approximately 192 days.

At an elevation of 1,142 feet, Clinton County receives approximately 38.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Ageratum during the growing season.

Annual Blooms in Multi-season Pollinator-friendly Good for cutting
Clinton County, IL (Zone 6b) Moderate season
192 days
Last Spring Frost April 10
192 growing days
First Fall Frost October 19

Clinton County Soil Profile

Soil Type

Silt Loam

Soil pH

6-7

Drainage

Well Drained

Ageratum Planting Risk Windows

Early Start (70% safe) ✓ Fits season (31 days to spare)
Start indoors: Feb 14 Transplant: Apr 4 🌸 Bloom: May 30 – Sep 12
Recommended (50%) ✓ Fits season (31 days to spare)
Start indoors: Feb 20 Transplant: Apr 10 🌸 Bloom: Jun 5 – Sep 18
Safe Start (90%) ✓ Fits season (33 days to spare)
Start indoors: Mar 1 Transplant: Apr 19 🌸 Bloom: Jun 14 – Sep 27

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 Clinton County

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

Soil pH

Your soil pH (6.0–7.0) is within Ageratum's preferred range (6.0–7.0).

Soil Texture

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

Organic Matter

Organic matter is excellent (4.5%) — Ageratum will thrive.

How to Plant Ageratum

8"
Between Plants
10"
Between Rows

Succession Planting Ageratum

3
successive plantings in your 192-day season

Sow every 6.9 weeks. Last sowing by Aug 05 to harvest before frost.

Ageratum Water Budget

Plant needs
1.0″/week
Rainfall provides
0.8″/week
You supply
0.2″/week
Watering frequency Only during dry spells
Season total 342 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

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 1.6" 0" ❄️ Dormant
Feb 1.7" 0" ❄️ Dormant
Mar 2.9" 0" ❄️ Dormant
Apr 4.3" 3.5" 0.8" 💧 Light watering
May 4.3" 4.3" 0" ✅ Rainfall sufficient
Jun 4.3" 4.9" 0" ✅ Rainfall sufficient
Jul 4.3" 4.3" 0" ✅ Rainfall sufficient
Aug 4.3" 3.9" 0.4" 💧 Light watering
Sep 4.3" 3.4" 0.9" 💧 Light watering
Oct 4.3" 3.2" 1.1" 💧 Light watering
Nov 2.6" 0" ❄️ Dormant
Dec 1.7" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Clinton 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 ~928 GDD — county provides 2,640 GDD Excellent fit

Ageratum Planting Timeline — Clinton County, IL

Ageratum Planting Calendar

Activity When Date Range
Start Indoors February 20 Feb 20 – Mar 6
Transplant Outdoors April 10 Apr 10 – Apr 24
Direct Sow April 10 Apr 10 – May 1
Bloom June 5 Jun 5 – Sep 18

· 8" apart · Rows 10" apart

Month-by-Month Timeline

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

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: ideal

🗺️ USDA Zone

Zone 6b

📆 Growing Season

192 days in Clinton County

Growing Tips for Ageratum in Clinton County

Direct sow Ageratum outdoors after April 10 in Clinton 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 Clinton County, IL?

Clinton County is in Zone 6b with an average last frost of April 10. Plan your Ageratum planting based on this frost date — see the calendar above for exact timing.

What planting zone is Clinton County, IL?

Clinton County, Illinois is in USDA Hardiness Zone 6b. The average last spring frost is April 10 and first fall frost is October 19.

When should I plant Ageratum in Clinton County, IL?

In Clinton County, IL, plant Ageratum after the last frost (around April 10) and before the first frost (around October 19). Best results when soil holds above 50°F.

What growing zone is Clinton County, IL for Ageratum?

Clinton County sits in USDA Zone 6b. Ageratum grows reliably in zones 3a through 11b, so it's a good fit here.

Can Ageratum grow in Clinton County's climate?

Yes — Ageratum grows well in Clinton County's temperate climate. Clinton County averages a 192-day frost-free season, with last frost around April 10 and first frost around October 19.

🌱

Your Clinton County Garden Planner — Free

A 22-page printable planner built for Clinton 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.

Instant PDF download. No spam, unsubscribe any time.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Clinton County, IL. Local conditions may vary. Last updated: July 2026.

Sources & credits

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