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When to plant Ageratum in Danforth, ME

For Ageratum in Danforth, the safe spring window opens around May 16 and closes around June 6. Last expected frost is May 9, first fall frost October 7, giving a 151-day growing season.

When to Plant Ageratum in Danforth, ME

Washington County, Maine Zone 5b July

July to-do list for Washington County, Maine

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

Avg. last frost May 9
Avg. first frost October 7
Soil temp (4") 71°F
Watering Low
Pest pressure High
Daylight 15.1 hrs
  1. It's harvest week for ageratum

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

August prep starts now
  • 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.

Danforth, Maine is in USDA Zone 5b. The average last spring frost is May 9 and the first fall frost is October 7, giving you a growing season of approximately 151 days.

At an elevation of 1,184 feet, Washington County receives approximately 43.9 inches of rainfall annually with predominantly silt loam soil. Summer highs average 80°F, so choose short-season varieties of Ageratum to ensure they mature before fall.

Annual Blooms in Multi-season Pollinator-friendly Good for cutting
Danforth, ME (Zone 5b) Moderate season
151 days
Last Spring Frost May 9
151 growing days
First Fall Frost October 7

Danforth Soil Profile

Soil Type

Silt Loam

Soil pH

5-6.5

Drainage

Well Drained

Ageratum Planting Risk Windows

Early Start (70% safe) ✓ Fits season (2 days to spare)
Start indoors: Mar 13 Transplant: May 8 🌸 Bloom: Jul 3 – Oct 2
Recommended (50%) ✗ May not fit
Start indoors: Mar 21 Transplant: May 16 🌸 Bloom: Jul 11 – Oct 10
Safe Start (90%) ✓ Fits season (4 days to spare)
Start indoors: Apr 8 Transplant: Jun 3 🌸 Bloom: Jul 29 – Oct 28

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 Danforth

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

Soil pH

Your soil pH (5.0–6.5) is more acidic than Ageratum prefers (6.0–7.0). Add garden lime to raise pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (3.7%). Annual compost additions will help Ageratum.

How to Plant Ageratum

8"
Between Plants
10"
Between Rows

Succession Planting Ageratum

2
successive plantings in your 151-day season

Sow every 6.9 weeks. Last sowing by Jul 24 to harvest before frost.

Ageratum Water Budget

Plant needs
1.0″/week
Rainfall provides
1.2″/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 3.2" 0" ❄️ Dormant
Feb 3" 0" ❄️ Dormant
Mar 4.1" 0" ❄️ Dormant
Apr 3.5" 0" ❄️ Dormant
May 4.3" 3.5" 0.8" 💧 Light watering
Jun 4.3" 4.7" 0" ✅ Rainfall sufficient
Jul 4.3" 4.1" 0.2" 💧 Light watering
Aug 4.3" 4.1" 0.2" 💧 Light watering
Sep 4.3" 3.8" 0.5" 💧 Light watering
Oct 4.3" 3.4" 0.9" 💧 Light watering
Nov 3.4" 0" ❄️ Dormant
Dec 3.2" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Washington 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 ~675 GDD — county provides 1,510 GDD Excellent fit

Ageratum Planting Timeline — Danforth, ME

Ageratum Planting Calendar

Activity When Date Range
Start Indoors March 21 Mar 21 – Apr 4
Transplant Outdoors May 16 May 16 – May 30
Direct Sow May 16 May 16 – Jun 6
Bloom July 11 Jul 11 – Oct 10

· 8" apart · Rows 10" apart

Month-by-Month Timeline

MonthActivities
January
February
March Start Indoors
April Start Indoors
May Transplant Outdoors Direct Sow
June 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 5b

📆 Growing Season

151 days in Washington County

Growing Tips for Ageratum in Danforth

Direct sow Ageratum outdoors after May 09 in Washington 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 Danforth, ME?

In Danforth, ME, plant Ageratum after the last frost (around May 9) and before the first frost (around October 7). Best results when soil holds above 50°F.

What growing zone is Danforth, ME for Ageratum?

Danforth sits in USDA Zone 5b. Ageratum grows reliably in zones 3a through 11b, so it's a good fit here.

Can Ageratum grow in Danforth's climate?

Yes — Ageratum grows well in Danforth's temperate climate. Danforth averages a 151-day frost-free season, with last frost around May 9 and first frost around October 7.

🌱

Your Washington County Garden Planner — Free

A 22-page printable planner built for Washington County (Zone 5b). 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 Washington County, ME. Local conditions may vary. Last updated: July 2026.