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When to Plant Ageratum in Blanco County, TX

Blanco County, Texas Zone 8b June

Blanco County, Texas gardeners: here's your June plan

Welcome to June in Zone 8b. These are the moves that will have the biggest impact on your growing season.

Avg. last frost March 8
Avg. first frost November 21
Soil temp (4") 70°F
Watering Low
Pest pressure High
Daylight 13.9 hrs
  1. Pick ageratum

    If you can't use it all right away, check the food-preservation section of your planner.

July 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.

Blanco County, Texas is in USDA Zone 8b. The average last spring frost is March 8 and the first fall frost is November 21, giving you a growing season of approximately 258 days.

At an elevation of 4,826 feet, Blanco County receives approximately 61.5 inches of rainfall annually with predominantly clay soil. Summer highs average 90°F, providing good warmth for Ageratum during the growing season. 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
Blanco County, TX (Zone 8b) Long season
258 days
Last Spring Frost March 8
258 growing days
First Fall Frost November 21
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Blanco County Soil Profile

Soil Type

Clay

Soil pH

7.1-7.7

Drainage

Well Drained

Ageratum Planting Risk Windows

Early Start (70% safe) ✓ Fits season (60 days to spare)
Start indoors: Jan 18 Transplant: Feb 15 🌸 Bloom: Apr 12 – Sep 13
Recommended (50%) ✓ Fits season (62 days to spare)
Start indoors: Jan 25 Transplant: Feb 22 🌸 Bloom: Apr 19 – Sep 20
Safe Start (90%) ✓ Fits season (51 days to spare)
Start indoors: Feb 24 Transplant: Mar 24 🌸 Bloom: May 19 – Oct 20

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 Blanco County

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

Soil pH

Your soil pH (7.1–7.7) is more alkaline than Ageratum prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

Your clay soil in Blanco County is workable for Ageratum. Add compost annually to improve structure.

Organic Matter

Organic matter is moderate (3.1%). Annual compost additions will help Ageratum.

How to Plant Ageratum

8"
Between Plants
10"
Between Rows

Succession Planting Ageratum

5
successive plantings in your 258-day season

Sow every 6.9 weeks. Last sowing by Sep 07 to harvest before frost.

Ageratum Water Budget

Plant needs
1.0″/week
Rainfall provides
1.0″/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 1.6" 0" ❄️ Dormant
Feb 1.8" 0" ❄️ Dormant
Mar 4.3" 4.3" 0" ✅ Rainfall sufficient
Apr 4.3" 5.8" 0" ✅ Rainfall sufficient
May 4.3" 10.3" 0" ✅ Rainfall sufficient
Jun 4.3" 9.9" 0" ✅ Rainfall sufficient
Jul 4.3" 7.7" 0" ✅ Rainfall sufficient
Aug 4.3" 6.7" 0" ✅ Rainfall sufficient
Sep 4.3" 6.4" 0" ✅ Rainfall sufficient
Oct 4.3" 3.4" 0.9" 💧 Light watering
Nov 4.3" 2" 2.3" 🚿 Regular watering
Dec 1.8" 0" ❄️ Dormant

Water needs are for active growing months only (Mar–Nov in Blanco 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 ~1,181 GDD — county provides 4,515 GDD Excellent fit

Ageratum Planting Timeline — Blanco County, TX

Ageratum Planting Calendar

Activity When Date Range
Start Indoors January 25 Jan 25 – Feb 8
Transplant Outdoors February 22 Feb 22 – Mar 8
Direct Sow February 22 Feb 22 – Mar 15
Bloom April 19 Apr 19 – Sep 20

· 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
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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_alkaline

🗺️ USDA Zone

Zone 8b

📆 Growing Season

258 days in Blanco County

Growing Tips for Ageratum in Blanco County

Direct sow Ageratum outdoors after March 08 in Blanco County when soil has warmed and frost danger has passed.

With Blanco County's clay soil (36% clay), work in 3-4 inches of compost before planting Ageratum. Avoid tilling when soil is wet to prevent compaction.

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 Blanco County, TX?

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

What planting zone is Blanco County, TX?

Blanco County, Texas is in USDA Hardiness Zone 8b. The average last spring frost is March 8 and first fall frost is November 21.

🌱

Your Blanco County Garden Planner — Free

A 22-page printable planner built for Blanco 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 Blanco County, TX. 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.