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When to Plant Ageratum in Colorado County, TX

Colorado County, Texas Zone 9a June

Your June planting checklist for Colorado County, Texas

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

Avg. last frost February 26
Avg. first frost December 4
Soil temp (4") 82°F
Watering Low
Pest pressure High
Daylight 13.9 hrs
  1. Collect ageratum at their peak

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

Looking ahead to July
  • 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.

Colorado County, Texas is in USDA Zone 9a. The average last spring frost is February 26 and the first fall frost is December 4, giving you a growing season of approximately 281 days.

At an elevation of 87 feet, Colorado County receives approximately 70.5 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
Colorado County, TX (Zone 9a) Year-round
281 days
Last Spring Frost February 26
281 growing days
First Fall Frost December 4

Colorado County Soil Profile

Soil Type

Clay

Soil pH

7.3-7.8

Drainage

Well Drained

Ageratum Planting Risk Windows

Early Start (70% safe) ✓ Fits season (74 days to spare)
Start indoors: Jan 1 Transplant: Jan 29 🌸 Bloom: Mar 26 – Sep 10
Recommended (50%) ✓ Fits season (71 days to spare)
Start indoors: Jan 15 Transplant: Feb 12 🌸 Bloom: Apr 9 – Sep 24
Safe Start (90%) ✓ Fits season (63 days to spare)
Start indoors: Feb 6 Transplant: Mar 6 🌸 Bloom: May 1 – Oct 16

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 Colorado County

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

Soil pH

Your soil pH (7.3–7.8) is more alkaline than Ageratum prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

Heavy clay soil (42% clay) in Colorado County compacts easily and drains slowly. Amend with compost and avoid working soil when wet.

Drainage

Drainage is adequate for Ageratum.

Organic Matter

Organic matter is moderate (2.8%). Annual compost additions will help Ageratum.

How to Plant Ageratum

8"
Between Plants
10"
Between Rows

Succession Planting Ageratum

5
successive plantings in your 281-day season

Sow every 6.9 weeks. Last sowing by Sep 20 to harvest before frost.

Ageratum Water Budget

Plant needs
1.0″/week
Rainfall provides
1.1″/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 1.9" 0" ❄️ Dormant
Feb 4.3" 2.3" 2" 💧 Light watering
Mar 4.3" 4.5" 0" ✅ Rainfall sufficient
Apr 4.3" 8" 0" ✅ Rainfall sufficient
May 4.3" 10.9" 0" ✅ Rainfall sufficient
Jun 4.3" 10.3" 0" ✅ Rainfall sufficient
Jul 4.3" 9.3" 0" ✅ Rainfall sufficient
Aug 4.3" 8.7" 0" ✅ Rainfall sufficient
Sep 4.3" 5.5" 0" ✅ Rainfall sufficient
Oct 4.3" 4.8" 0" ✅ Rainfall sufficient
Nov 4.3" 2.3" 2" 💧 Light watering
Dec 4.3" 1.9" 2.4" 🚿 Regular watering

Water needs are for active growing months only (Feb–Dec in Colorado 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 4,935 GDD Excellent fit

Ageratum Planting Timeline — Colorado County, TX

Ageratum Planting Calendar

Activity When Date Range
Start Indoors January 15 Jan 15 – Jan 29
Transplant Outdoors February 12 Feb 12 – Feb 26
Direct Sow February 12 Feb 12 – Mar 5
Bloom April 9 Apr 9 – Sep 24

· 8" apart · Rows 10" apart

Month-by-Month Timeline

MonthActivities
January Start Indoors
February Transplant Outdoors Direct Sow
March 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 · Natural rainfall sufficient

📅 Days to Maturity

60–75 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 9a

📆 Growing Season

281 days in Colorado County

Growing Tips for Ageratum in Colorado County

Direct sow Ageratum outdoors after February 26 in Colorado County when soil has warmed and frost danger has passed.

With Colorado County's clay soil (42% 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 Colorado County, TX?

Colorado County is in Zone 9a with an average last frost of February 26. Plan your Ageratum planting based on this frost date — see the calendar above for exact timing.

What planting zone is Colorado County, TX?

Colorado County, Texas is in USDA Hardiness Zone 9a. The average last spring frost is February 26 and first fall frost is December 4.

🌱

Your Colorado County Garden Planner — Free

A 22-page printable planner built for Colorado County (Zone 9a). 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 Colorado 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.