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When to plant Ageratum in Washington County, AL

Washington County gardeners should plant Ageratum between February 26 and March 19 in spring. With Washington County's Zone 8b climate (last frost March 12), Ageratum needs 60–75 days to mature — plant by August 30 for a full harvest.

When to Plant Ageratum in Washington County, AL

Washington County, Alabama Zone 8b July

Your July gardening checklist

Your garden in Washington County, Alabama is working on a schedule, even when you're not. Here's where you should be this July.

Avg. last frost March 12
Avg. first frost November 13
Soil temp (4") 89°F
Watering Low
Pest pressure High
Daylight 13.9 hrs
  1. It's harvest week for ageratum

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  • 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.

Washington County, Alabama is in USDA Zone 8b. The average last spring frost is March 12 and the first fall frost is November 13, giving you a growing season of approximately 246 days.

At an elevation of 419 feet, Washington County receives approximately 54.8 inches of rainfall annually with predominantly clay loam soil. Summer highs average 97°F, so Ageratum may need afternoon shade and extra watering during peak heat. Clay soil retains moisture well for Ageratum, but amend with compost to improve drainage and prevent root rot. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Ageratum root diseases.

Annual Blooms in Multi-season Pollinator-friendly Good for cutting
Washington County, AL (Zone 8b) Long season
246 days
Last Spring Frost March 12
246 growing days
First Fall Frost November 13

Washington County Soil Profile

Soil Type

Clay Loam

Soil pH

5.3-6.6

Drainage

Well Drained

Ageratum Planting Risk Windows

Early Start (70% safe) ✓ Fits season (51 days to spare)
Start indoors: Jan 20 Transplant: Feb 17 🌸 Bloom: Apr 14 – Sep 15
Recommended (50%) ✓ Fits season (50 days to spare)
Start indoors: Jan 29 Transplant: Feb 26 🌸 Bloom: Apr 23 – Sep 24
Safe Start (90%) ✓ Fits season (46 days to spare)
Start indoors: Feb 21 Transplant: Mar 21 🌸 Bloom: May 16 – Oct 17

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 Washington County

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

Soil pH

Your soil pH (5.3–6.6) is more acidic than Ageratum prefers (6.0–7.0). Add garden lime to raise pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.4%). Annual compost additions will help Ageratum.

How to Plant Ageratum

8"
Between Plants
10"
Between Rows

Succession Planting Ageratum

4
successive plantings in your 246-day season

Sow every 6.9 weeks. Last sowing by Aug 30 to harvest before frost.

Ageratum Water Budget

Plant needs
1.0″/week
Rainfall provides
0.9″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 141 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 4.3" 0" ❄️ Dormant
Feb 5.1" 0" ❄️ Dormant
Mar 4.3" 5.4" 0" ✅ Rainfall sufficient
Apr 4.3" 3.7" 0.6" 💧 Light watering
May 4.3" 4.8" 0" ✅ Rainfall sufficient
Jun 4.3" 4.5" 0" ✅ Rainfall sufficient
Jul 4.3" 5.1" 0" ✅ Rainfall sufficient
Aug 4.3" 5.4" 0" ✅ Rainfall sufficient
Sep 4.3" 3.6" 0.7" 💧 Light watering
Oct 4.3" 3" 1.3" 💧 Light watering
Nov 4.3" 4.8" 0" ✅ Rainfall sufficient
Dec 5" 0" ❄️ Dormant

Water needs are for active growing months only (Mar–Nov 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 ~1,536 GDD — county provides 5,596 GDD Excellent fit

Ageratum Planting Timeline — Washington County, AL

Ageratum Planting Calendar

Activity When Date Range
Start Indoors January 29 Jan 29 – Feb 12
Transplant Outdoors February 26 Feb 26 – Mar 12
Direct Sow February 26 Feb 26 – Mar 19
Bloom April 23 Apr 23 – Sep 24

· 8" apart · Rows 10" apart

Month-by-Month Timeline

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

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: too_acidic

🗺️ USDA Zone

Zone 8b

📆 Growing Season

246 days in Washington County

Growing Tips for Ageratum in Washington County

Direct sow Ageratum outdoors after March 12 in Washington County when soil has warmed and frost danger has passed.

With Washington County's clay soil (34% clay), work in 3-4 inches of compost before planting Ageratum. Avoid tilling when soil is wet to prevent compaction.

With summer highs reaching 97°F in Washington County, provide afternoon shade for Ageratum and water deeply in the morning.

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 Washington County, AL?

Washington County is in Zone 8b with an average last frost of March 12. Plan your Ageratum planting based on this frost date — see the calendar above for exact timing.

What planting zone is Washington County, AL?

Washington County, Alabama is in USDA Hardiness Zone 8b. The average last spring frost is March 12 and first fall frost is November 13.

When should I plant Ageratum in Washington County, AL?

In Washington County, AL, plant Ageratum after the last frost (around March 12) and before the first frost (around November 13). Best results when soil holds above 50°F.

What growing zone is Washington County, AL for Ageratum?

Washington County sits in USDA Zone 8b. Ageratum grows reliably in zones 3a through 11b, so it's a good fit here.

Can Ageratum grow in Washington County's climate?

Yes — Ageratum grows well in Washington County's temperate climate. Washington County averages a 246-day frost-free season, with last frost around March 12 and first frost around November 13.

🌱

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A 22-page printable planner built for Washington County (Zone 8b). 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, AL. Local conditions may vary. Last updated: July 2026.

Sources & credits

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