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When to Plant Ageratum in Ottawa County, OH

Ottawa County, Ohio Zone 6b June

June in the garden — Ottawa County, Ohio

A quick June briefing for Ottawa County, Ohio gardeners — what's urgent, what's next, and what can wait.

Avg. last frost April 25
Avg. first frost October 25
Soil temp (4") 73°F
Watering Low
Pest pressure High
Daylight 15 hrs
  1. Time to start ageratum inside

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

  2. Basket week: ageratum

    Check every 1–2 days. Many of these get tough or go to seed if you wait too long.

Get ahead of 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.

Ottawa County, Ohio is in USDA Zone 6b. The average last spring frost is April 25 and the first fall frost is October 25, giving you a growing season of approximately 183 days.

At an elevation of 1,264 feet, Ottawa County receives approximately 31.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 88°F, providing good warmth for Ageratum during the growing season.

Annual Blooms in Multi-season Pollinator-friendly Good for cutting
Ottawa County, OH (Zone 6b) Moderate season
183 days
Last Spring Frost April 25
183 growing days
First Fall Frost October 25
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Ottawa County Soil Profile

Soil Type

Silt Loam

Soil pH

6.2-7

Drainage

Well Drained

Ageratum Planting Risk Windows

Early Start (70% safe) ✓ Fits season (21 days to spare)
Start indoors: Feb 28 Transplant: Apr 18 🌸 Bloom: Jun 13 – Sep 26
Recommended (50%) ✓ Fits season (22 days to spare)
Start indoors: Mar 7 Transplant: Apr 25 🌸 Bloom: Jun 20 – Oct 3
Safe Start (90%) ✓ Fits season (22 days to spare)
Start indoors: Mar 15 Transplant: May 3 🌸 Bloom: Jun 28 – Oct 11

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 Ottawa County

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

Soil pH

Your soil pH (6.2–7.0) is within Ageratum's preferred range (6.0–7.0).

Soil Texture

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

Organic Matter

Organic matter is excellent (5.1%) — 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 11 to harvest before frost.

Ageratum Water Budget

Plant needs
1.0″/week
Rainfall provides
0.7″/week
You supply
0.3″/week
Watering frequency Only during dry spells
Season total 466 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 1.3" 0" ❄️ Dormant
Mar 1.9" 0" ❄️ Dormant
Apr 4.3" 3.2" 1.1" 💧 Light watering
May 4.3" 3.9" 0.4" 💧 Light watering
Jun 4.3" 3.9" 0.4" 💧 Light watering
Jul 4.3" 3.3" 1" 💧 Light watering
Aug 4.3" 2.9" 1.4" 💧 Light watering
Sep 4.3" 3.1" 1.2" 💧 Light watering
Oct 4.3" 2.2" 2.1" 💧 Light watering
Nov 2.2" 0" ❄️ Dormant
Dec 1.6" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Ottawa 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 ~1,080 GDD — county provides 2,928 GDD Excellent fit

Ageratum Planting Timeline — Ottawa County, OH

Ageratum Planting Calendar

Activity When Date Range
Start Indoors March 7 Mar 7 – Mar 21
Transplant Outdoors April 25 Apr 25 – May 9
Direct Sow April 25 Apr 25 – May 16
Bloom June 20 Jun 20 – Oct 3

· 8" apart · Rows 10" apart

Month-by-Month Timeline

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

🗺️ USDA Zone

Zone 6b

📆 Growing Season

183 days in Ottawa County

Growing Tips for Ageratum in Ottawa County

Direct sow Ageratum outdoors after April 25 in Ottawa 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 Ottawa County, OH?

Ottawa County is in Zone 6b with an average last frost of April 25. Plan your Ageratum planting based on this frost date — see the calendar above for exact timing.

What planting zone is Ottawa County, OH?

Ottawa County, Ohio is in USDA Hardiness Zone 6b. The average last spring frost is April 25 and first fall frost is October 25.

🌱

Your Ottawa County Garden Planner — Free

A 22-page printable planner built for Ottawa 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.

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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 Ottawa County, OH. 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.