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When to plant Ageratum in Bath, IL

For Ageratum in Bath, the safe spring window opens around April 15 and closes around May 6. Last expected frost is April 15, first fall frost October 14, giving a 182-day growing season.

When to Plant Ageratum in Bath, IL

Mason County, Illinois Zone 6a July

Your July planting checklist for Mason County, Illinois

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

Avg. last frost April 15
Avg. first frost October 14
Soil temp (4") 77°F
Watering Moderate
Pest pressure High
Daylight 14.6 hrs
  1. Pick ageratum

    This is the payoff month. Bring a basket, bring a friend, and get into the beds.

Looking ahead to August
  • 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.

Bath, Illinois is in USDA Zone 6a. The average last spring frost is April 15 and the first fall frost is October 14, giving you a growing season of approximately 182 days.

At an elevation of 768 feet, Mason County receives approximately 30.4 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
Bath, IL (Zone 6a) Moderate season
182 days
Last Spring Frost April 15
182 growing days
First Fall Frost October 14

Bath Soil Profile

Soil Type

Silt Loam

Soil pH

6.1-6.9

Drainage

Well Drained

Ageratum Planting Risk Windows

Early Start (70% safe) ✓ Fits season (24 days to spare)
Start indoors: Feb 22 Transplant: Apr 12 🌸 Bloom: Jun 7 – Sep 13
Recommended (50%) ✓ Fits season (28 days to spare)
Start indoors: Feb 25 Transplant: Apr 15 🌸 Bloom: Jun 10 – Sep 16
Safe Start (90%) ✓ Fits season (27 days to spare)
Start indoors: Mar 12 Transplant: Apr 30 🌸 Bloom: Jun 25 – Oct 1

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 Bath

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

Soil pH

Your soil pH (6.1–6.9) is within Ageratum's preferred range (6.0–7.0).

Soil Texture

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

Organic Matter

Organic matter is excellent (4.8%) — Ageratum will thrive.

How to Plant Ageratum

8"
Between Plants
10"
Between Rows

Succession Planting Ageratum

3
successive plantings in your 182-day season

Sow every 6.9 weeks. Last sowing by Jul 31 to harvest before frost.

Ageratum Water Budget

Plant needs
1.0″/week
Rainfall provides
0.7″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 580 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 1.3" 0" ❄️ Dormant
Feb 1.5" 0" ❄️ Dormant
Mar 2" 0" ❄️ Dormant
Apr 4.3" 3" 1.3" 💧 Light watering
May 4.3" 3.3" 1" 💧 Light watering
Jun 4.3" 4.1" 0.2" 💧 Light watering
Jul 4.3" 3.3" 1" 💧 Light watering
Aug 4.3" 3.4" 0.9" 💧 Light watering
Sep 4.3" 2.7" 1.6" 💧 Light watering
Oct 4.3" 2.2" 2.1" 💧 Light watering
Nov 2" 0" ❄️ Dormant
Dec 1.8" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Mason 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 2,639 GDD Excellent fit

Ageratum Planting Timeline — Bath, IL

Ageratum Planting Calendar

Activity When Date Range
Start Indoors February 25 Feb 25 – Mar 11
Transplant Outdoors April 15 Apr 15 – Apr 29
Direct Sow April 15 Apr 15 – May 6
Bloom June 10 Jun 10 – Sep 16

· 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 · 1-2 times/week

📅 Days to Maturity

60–75 days

🧪 Soil pH

Needs 6–7 · Your soil: ideal

🗺️ USDA Zone

Zone 6a

📆 Growing Season

182 days in Mason County

Growing Tips for Ageratum in Bath

Direct sow Ageratum outdoors after April 15 in Mason 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 →

When should I plant Ageratum in Bath, IL?

In Bath, IL, plant Ageratum after the last frost (around April 15) and before the first frost (around October 14). Best results when soil holds above 50°F.

What growing zone is Bath, IL for Ageratum?

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

Can Ageratum grow in Bath's climate?

Yes — Ageratum grows well in Bath's temperate climate. Bath averages a 182-day frost-free season, with last frost around April 15 and first frost around October 14.

🌱

Your Mason County Garden Planner — Free

A 22-page printable planner built for Mason County (Zone 6a). 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 Mason County, IL. Local conditions may vary. Last updated: July 2026.