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When to Plant Ageratum in Brazos County, TX

Brazos County, Texas Zone 9a June

Top priorities for Brazos County, Texas gardeners in June

Your Brazos County, Texas garden is entering a new phase. Here's what's on the schedule for June and why each task matters now.

Avg. last frost March 4
Avg. first frost November 25
Soil temp (4") 83°F
Watering Low
Pest pressure High
Daylight 14 hrs
  1. Collect ageratum at their peak

    This is the payoff month. Bring a basket, bring a friend, and get into the beds.

July will be here before you know it — start on
  • 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.

Brazos County, Texas is in USDA Zone 9a. The average last spring frost is March 4 and the first fall frost is November 25, giving you a growing season of approximately 266 days.

At an elevation of 74 feet, Brazos County receives approximately 63.5 inches of rainfall annually with predominantly clay soil. Summer highs average 91°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
Brazos County, TX (Zone 9a) Long season
266 days
Last Spring Frost March 4
266 growing days
First Fall Frost November 25
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Brazos County Soil Profile

Soil Type

Clay

Soil pH

6.7-7.8

Drainage

Well Drained

Ageratum Planting Risk Windows

Early Start (70% safe) ✓ Fits season (57 days to spare)
Start indoors: Jan 8 Transplant: Feb 5 🌸 Bloom: Apr 2 – Sep 17
Recommended (50%) ✓ Fits season (56 days to spare)
Start indoors: Jan 21 Transplant: Feb 18 🌸 Bloom: Apr 15 – Sep 30
Safe Start (90%) ✓ Fits season (44 days to spare)
Start indoors: Feb 22 Transplant: Mar 22 🌸 Bloom: May 17 – Nov 1

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 Brazos County

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

Soil pH

Your soil pH (6.7–7.8) is more alkaline than Ageratum prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

Heavy clay soil (44% clay) in Brazos 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 (2.7%). Annual compost additions will help Ageratum.

How to Plant Ageratum

8"
Between Plants
10"
Between Rows

Succession Planting Ageratum

5
successive plantings in your 266-day season

Sow every 6.9 weeks. Last sowing by Sep 11 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
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

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 1.4" 0" ❄️ Dormant
Feb 2.2" 0" ❄️ Dormant
Mar 4.3" 3.9" 0.4" 💧 Light watering
Apr 4.3" 7.4" 0" ✅ Rainfall sufficient
May 4.3" 8.5" 0" ✅ Rainfall sufficient
Jun 4.3" 10.4" 0" ✅ Rainfall sufficient
Jul 4.3" 8.9" 0" ✅ Rainfall sufficient
Aug 4.3" 7.7" 0" ✅ Rainfall sufficient
Sep 4.3" 5.5" 0" ✅ Rainfall sufficient
Oct 4.3" 4" 0.3" 💧 Light watering
Nov 4.3" 2.2" 2.1" 💧 Light watering
Dec 1.4" 0" ❄️ Dormant

Water needs are for active growing months only (Mar–Nov in Brazos 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 ~1,232 GDD — county provides 4,854 GDD Excellent fit

Ageratum Planting Timeline — Brazos County, TX

Ageratum Planting Calendar

Activity When Date Range
Start Indoors January 21 Jan 21 – Feb 4
Transplant Outdoors February 18 Feb 18 – Mar 4
Direct Sow February 18 Feb 18 – Mar 11
Bloom April 15 Apr 15 – Sep 30

· 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 9a

📆 Growing Season

266 days in Brazos County

Growing Tips for Ageratum in Brazos County

Direct sow Ageratum outdoors after March 04 in Brazos County when soil has warmed and frost danger has passed.

With Brazos County's clay soil (44% 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 Brazos County, TX?

Brazos County is in Zone 9a with an average last frost of March 4. Plan your Ageratum planting based on this frost date — see the calendar above for exact timing.

What planting zone is Brazos County, TX?

Brazos County, Texas is in USDA Hardiness Zone 9a. The average last spring frost is March 4 and first fall frost is November 25.

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Your Brazos County Garden Planner — Free

A 22-page printable planner built for Brazos 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 Brazos 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.