Blog

When to plant Ageratum in Howard County County,

Howard County County's spring Ageratum window runs April 22 through May 13. time plantings around the expected last-frost window for best survival.

When to Plant Ageratum in Howard County, IN

Howard County, Indiana Zone 6a June

June to-do list for Howard County, Indiana

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 22
Avg. first frost October 17
Soil temp (4") 67°F
Watering Low
Pest pressure High
Daylight 14.9 hrs
  1. Sow ageratum in trays indoors

    Starting these indoors now means sturdy transplants ready the moment your soil warms up.

  2. Harvest ageratum as they ripen

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

Looking ahead to July
  • 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.

Howard County, Indiana is in USDA Zone 6a. The average last spring frost is April 22 and the first fall frost is October 17, giving you a growing season of approximately 178 days.

At an elevation of 1,303 feet, Howard County receives approximately 41.8 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
Howard County, IN (Zone 6a) Moderate season
178 days
Last Spring Frost April 22
178 growing days
First Fall Frost October 17
Share this guide:

Howard County Soil Profile

Soil Type

Silt Loam

Soil pH

6.1-7.1

Drainage

Well Drained

Ageratum Planting Risk Windows

Early Start (70% safe) ✓ Fits season (26 days to spare)
Start indoors: Feb 25 Transplant: Apr 15 🌸 Bloom: Jun 10 – Sep 16
Recommended (50%) ✓ Fits season (24 days to spare)
Start indoors: Mar 4 Transplant: Apr 22 🌸 Bloom: Jun 17 – Sep 23
Safe Start (90%) ✓ Fits season (21 days to spare)
Start indoors: Mar 20 Transplant: May 8 🌸 Bloom: Jul 3 – Oct 9

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 Howard County

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

Soil pH

Your soil pH (6.1–7.1) overlaps with Ageratum's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is excellent (4.2%) — Ageratum will thrive.

How to Plant Ageratum

8"
Between Plants
10"
Between Rows

Succession Planting Ageratum

3
successive plantings in your 178-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
1.0″/week
You supply
0.0″/week
Watering frequency Only during dry spells
Season total 22 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 1.9" 0" ❄️ Dormant
Feb 1.6" 0" ❄️ Dormant
Mar 2.9" 0" ❄️ Dormant
Apr 4.3" 3.7" 0.6" 💧 Light watering
May 4.3" 4.4" 0" ✅ Rainfall sufficient
Jun 4.3" 4.8" 0" ✅ Rainfall sufficient
Jul 4.3" 4.8" 0" ✅ Rainfall sufficient
Aug 4.3" 4.7" 0" ✅ Rainfall sufficient
Sep 4.3" 4" 0.3" 💧 Light watering
Oct 4.3" 3.6" 0.7" 💧 Light watering
Nov 2.9" 0" ❄️ Dormant
Dec 2.3" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Howard 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 2,581 GDD Excellent fit

Ageratum Planting Timeline — Howard County, IN

Ageratum Planting Calendar

Activity When Date Range
Start Indoors March 4 Mar 4 – Mar 18
Transplant Outdoors April 22 Apr 22 – May 6
Direct Sow April 22 Apr 22 – May 13
Bloom June 17 Jun 17 – Sep 23

· 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
November
December
Share this guide:

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: acceptable

🗺️ USDA Zone

Zone 6a

📆 Growing Season

178 days in Howard County

Growing Tips for Ageratum in Howard County

Direct sow Ageratum outdoors after April 22 in Howard 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 Howard County, IN?

Howard County is in Zone 6a with an average last frost of April 22. Plan your Ageratum planting based on this frost date — see the calendar above for exact timing.

What planting zone is Howard County, IN?

Howard County, Indiana is in USDA Hardiness Zone 6a. The average last spring frost is April 22 and first fall frost is October 17.

When should I plant Ageratum in Howard County County, ?

In Howard County County, , plant Ageratum after the last frost (around April 22) and before the first frost (around October 17). Best results when soil holds above 50°F.

What growing zone is Howard County County, for Ageratum?

Howard County 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 Howard County County's climate?

Yes — Ageratum grows well in Howard County County's temperate climate. Howard County County averages a 178-day frost-free season, with last frost around April 22 and first frost around October 17.

🌱

Your Howard County Garden Planner — Free

A 22-page printable planner built for Howard 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.

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 Howard County, IN. 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.