Blog

When to Plant Ageratum in Hamilton County, NY

Hamilton County, New York Zone 4b June

Your June gardening checklist

June rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Hamilton County, New York.

Avg. last frost May 20
Avg. first frost September 28
Soil temp (4") 63°F
Watering Low
Pest pressure Moderate
Daylight 15.2 hrs
Get ahead of July
  • Starting indoors: ageratum
  • 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.

Hamilton County, New York is in USDA Zone 4b. The average last spring frost is May 20 and the first fall frost is September 28, giving you a growing season of approximately 131 days.

At an elevation of 959 feet, Hamilton County receives approximately 49.2 inches of rainfall annually with predominantly silt loam soil. Summer highs average 81°F, so choose short-season varieties of Ageratum to ensure they mature before fall.

Annual Blooms in Multi-season Pollinator-friendly Good for cutting
Hamilton County, NY (Zone 4b) Short season
131 days
Last Spring Frost May 20
131 growing days
First Fall Frost September 28

Hamilton County Soil Profile

Soil Type

Silt Loam

Soil pH

5.2-6.2

Drainage

Well Drained

Ageratum Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 25 Transplant: May 20 🌸 Bloom: Jul 15 – Sep 30
Recommended (50%) ✗ May not fit
Start indoors: Apr 1 Transplant: May 27 🌸 Bloom: Jul 22 – Oct 7
Safe Start (90%) ✗ May not fit
Start indoors: Apr 12 Transplant: Jun 7 🌸 Bloom: Aug 2 – Oct 18

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 Hamilton County

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

Soil pH

Your soil pH (5.2–6.2) is more acidic than Ageratum prefers (6.0–7.0). Add garden lime to raise pH.

Soil Texture

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

Drainage

Drainage is adequate for Ageratum.

Organic Matter

Organic matter is moderate (3.4%). Annual compost additions will help Ageratum.

How to Plant Ageratum

8"
Between Plants
10"
Between Rows

Succession Planting Ageratum

2
successive plantings in your 131-day season

Sow every 6.9 weeks. Last sowing by Jul 15 to harvest before frost.

Ageratum Water Budget

Plant needs
1.0″/week
Rainfall provides
1.6″/week
Watering frequency Natural rainfall sufficient
Season total 0 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 4" 0" ❄️ Dormant
Feb 2.9" 0" ❄️ Dormant
Mar 3.5" 0" ❄️ Dormant
Apr 4.8" 0" ❄️ Dormant
May 4.3" 4.1" 0.2" 💧 Light watering
Jun 4.3" 5" 0" ✅ Rainfall sufficient
Jul 4.3" 5.1" 0" ✅ Rainfall sufficient
Aug 4.3" 4.3" 0" ✅ Rainfall sufficient
Sep 4.3" 4.6" 0" ✅ Rainfall sufficient
Oct 3.9" 0" ❄️ Dormant
Nov 3.7" 0" ❄️ Dormant
Dec 3.4" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Hamilton 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 ~726 GDD — county provides 1,408 GDD Excellent fit

Ageratum Planting Timeline — Hamilton County, NY

Ageratum Planting Calendar

Activity When Date Range
Start Indoors April 1 Apr 1 – Apr 15
Transplant Outdoors May 27 May 27 – Jun 10
Direct Sow May 27 May 27 – Jun 17
Bloom July 22 Jul 22 – Oct 7

· 8" apart · Rows 10" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Natural rainfall sufficient

📅 Days to Maturity

60–75 days

🧪 Soil pH

Needs 6–7 · Your soil: too_acidic

🗺️ USDA Zone

Zone 4b

📆 Growing Season

131 days in Hamilton County

Growing Tips for Ageratum in Hamilton County

Direct sow Ageratum outdoors after May 20 in Hamilton 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 Hamilton County, NY?

Hamilton County is in Zone 4b with an average last frost of May 20. Plan your Ageratum planting based on this frost date — see the calendar above for exact timing.

What planting zone is Hamilton County, NY?

Hamilton County, New York is in USDA Hardiness Zone 4b. The average last spring frost is May 20 and first fall frost is September 28.

🌱

Your Hamilton County Garden Planner — Free

A 22-page printable planner built for Hamilton County (Zone 4b). 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 Hamilton County, NY. 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.