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When to plant Ageratum in Dewitt,

Ageratum planted in Dewitt between April 15 and May 6 matures in 75 days — well before the October 17 first frost.

When to Plant Ageratum in Dewitt, IL

Dewitt, IL Zone 6a June

What to do in June

If you only do a handful of things in the garden this June, make it these. They're sequenced around your zone's frost timing.

Avg. last frost April 15
Avg. first frost October 17
Soil temp (4") 71°F
Watering Low
Pest pressure High
Daylight 14.8 hrs
  1. Fire up the seed-starting tray: ageratum

    Label every cell. You will absolutely forget which is which otherwise.

  2. Pick ageratum

    Taste as you pick. The first ripe produce is the best feedback loop you'll get all season.

Before July arrives, get these ready
  • 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.

Dewitt, Illinois is in USDA Zone 6a. The average last spring frost is April 15 and the first fall frost is October 17, giving you a growing season of approximately 185 days.

At an elevation of 801 feet, DeWitt County receives approximately 31.8 inches of rainfall annually with predominantly silt loam soil. Summer highs average 84°F, so choose short-season varieties of Ageratum to ensure they mature before fall.

Annual Blooms in Multi-season Pollinator-friendly Good for cutting
Dewitt, IL (Zone 6a) Moderate season
185 days
Last Spring Frost April 15
185 growing days
First Fall Frost October 17

Dewitt Soil Profile

Soil Type

Silt Loam

Soil pH

6.1-7

Drainage

Well Drained

Ageratum Planting Risk Windows

Early Start (70% safe) ✓ Fits season (30 days to spare)
Start indoors: Feb 20 Transplant: Apr 10 🌸 Bloom: Jun 5 – Sep 11
Recommended (50%) ✓ Fits season (31 days to spare)
Start indoors: Feb 25 Transplant: Apr 15 🌸 Bloom: Jun 10 – Sep 16
Safe Start (90%) ✓ Fits season (33 days to spare)
Start indoors: Mar 10 Transplant: Apr 28 🌸 Bloom: Jun 23 – Sep 29

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 Dewitt

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

Soil pH

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

Soil Texture

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

Drainage

Drainage is adequate for Ageratum.

Organic Matter

Organic matter is excellent (5.0%) — Ageratum will thrive.

How to Plant Ageratum

8"
Between Plants
10"
Between Rows

Succession Planting Ageratum

3
successive plantings in your 185-day season

Sow every 6.9 weeks. Last sowing by Aug 03 to harvest before frost.

Ageratum Water Budget

Plant needs
1.0″/week
Rainfall provides
0.7″/week
You supply
0.6″/week
Watering frequency 1-2 times/week
Season total 952 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 1.4" 0" ❄️ Dormant
Feb 1.2" 0" ❄️ Dormant
Mar 2.3" 0" ❄️ Dormant
Apr 4.3" 2.6" 1.7" 💧 Light watering
May 4.3" 4.1" 0.2" 💧 Light watering
Jun 4.3" 4.3" 0" ✅ Rainfall sufficient
Jul 4.3" 3.2" 1.1" 💧 Light watering
Aug 4.3" 3.6" 0.7" 💧 Light watering
Sep 4.3" 2.7" 1.6" 💧 Light watering
Oct 4.3" 2.3" 2" 💧 Light watering
Nov 2.1" 0" ❄️ Dormant
Dec 2" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in DeWitt 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 ~878 GDD — county provides 2,405 GDD Excellent fit

Ageratum Planting Timeline — Dewitt, 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

185 days in DeWitt County

Growing Tips for Ageratum in Dewitt

Direct sow Ageratum outdoors after April 15 in DeWitt 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 Dewitt, ?

In Dewitt, , plant Ageratum after the last frost (around April 15) and before the first frost (around October 17). Best results when soil holds above 50°F.

What growing zone is Dewitt, for Ageratum?

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

Can Ageratum grow in Dewitt's climate?

Yes — Ageratum grows well in Dewitt's temperate climate. Dewitt averages a 185-day frost-free season, with last frost around April 15 and first frost around October 17.

🌱

Your DeWitt County Garden Planner — Free

A 22-page printable planner built for DeWitt 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 DeWitt County, IL. Local conditions may vary. Last updated: June 2026.