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When to plant Ageratum in McDonough County County,

Spring Ageratum in McDonough County County goes in April 17–May 8, once nighttime temps stop dipping near freezing.

When to Plant Ageratum in McDonough County, IL

McDonough County, Illinois Zone 6a June

McDonough County, Illinois gardeners: here's your June plan

June is a pivotal month for McDonough County, Illinois gardens. Focus on these tasks first and you'll set up the rest of the season for success.

Avg. last frost April 17
Avg. first frost October 17
Soil temp (4") 68°F
Watering Low
Pest pressure High
Daylight 14.9 hrs
  1. Indoor seed-starting week for ageratum

    You're about 17 weeks out from your last frost — the perfect window to get these germinating indoors.

  2. Pick ageratum

    Morning harvests are best — cooler temperatures mean crisper produce and longer fridge life.

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.

McDonough County, Illinois is in USDA Zone 6a. The average last spring frost is April 17 and the first fall frost is October 17, giving you a growing season of approximately 183 days.

At an elevation of 738 feet, McDonough County receives approximately 37.3 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
McDonough County, IL (Zone 6a) Moderate season
183 days
Last Spring Frost April 17
183 growing days
First Fall Frost October 17

McDonough County Soil Profile

Soil Type

Silt Loam

Soil pH

6.2-7.3

Drainage

Well Drained

Ageratum Planting Risk Windows

Early Start (70% safe) ✓ Fits season (29 days to spare)
Start indoors: Feb 21 Transplant: Apr 11 🌸 Bloom: Jun 6 – Sep 12
Recommended (50%) ✓ Fits season (29 days to spare)
Start indoors: Feb 27 Transplant: Apr 17 🌸 Bloom: Jun 12 – Sep 18
Safe Start (90%) ✓ Fits season (30 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 McDonough County

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

Soil pH

Your soil pH (6.2–7.3) overlaps with Ageratum's range (6.0–7.0), though not a perfect match.

Soil Texture

The silt loam soil in McDonough 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 (4.3%) — Ageratum will thrive.

How to Plant Ageratum

8"
Between Plants
10"
Between Rows

Succession Planting Ageratum

3
successive plantings in your 183-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
0.9″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 723 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 1.7" 0" ❄️ Dormant
Feb 1.8" 0" ❄️ Dormant
Mar 2.2" 0" ❄️ Dormant
Apr 4.3" 3.2" 1.1" 💧 Light watering
May 4.3" 4.8" 0" ✅ Rainfall sufficient
Jun 4.3" 4.1" 0.2" 💧 Light watering
Jul 4.3" 4.6" 0" ✅ Rainfall sufficient
Aug 4.3" 3.8" 0.5" 💧 Light watering
Sep 4.3" 3.5" 0.8" 💧 Light watering
Oct 4.3" 3.3" 1" 💧 Light watering
Nov 2.4" 0" ❄️ Dormant
Dec 1.9" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in McDonough 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 2,379 GDD Excellent fit

Ageratum Planting Timeline — McDonough County, IL

Ageratum Planting Calendar

Activity When Date Range
Start Indoors February 27 Feb 27 – Mar 13
Transplant Outdoors April 17 Apr 17 – May 1
Direct Sow April 17 Apr 17 – May 8
Bloom June 12 Jun 12 – 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 Transplant Outdoors 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: acceptable

🗺️ USDA Zone

Zone 6a

📆 Growing Season

183 days in McDonough County

Growing Tips for Ageratum in McDonough County

Direct sow Ageratum outdoors after April 17 in McDonough 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 McDonough County, IL?

McDonough County is in Zone 6a with an average last frost of April 17. Plan your Ageratum planting based on this frost date — see the calendar above for exact timing.

What planting zone is McDonough County, IL?

McDonough County, Illinois is in USDA Hardiness Zone 6a. The average last spring frost is April 17 and first fall frost is October 17.

When should I plant Ageratum in McDonough County, ?

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

What growing zone is McDonough County, for Ageratum?

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

Can Ageratum grow in McDonough County's climate?

Yes — Ageratum grows well in McDonough County's temperate climate. McDonough County averages a 183-day frost-free season, with last frost around April 17 and first frost around October 17.

🌱

Your McDonough County Garden Planner — Free

A 22-page printable planner built for McDonough 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 McDonough County, IL. 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.