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When to Plant Ageratum in Calhoun County, TX

Calhoun County, Texas Zone 9b June

This month in Calhoun County, Texas

We've pulled the most time-sensitive tasks for Calhoun County, Texas this June and put them front and centre. Tackle them in order.

Avg. last frost February 16
Avg. first frost December 7
Soil temp (4") 86°F
Watering Low
Pest pressure High
Daylight 13.8 hrs
  1. Start harvesting ageratum

    Don't tug. Use scissors or pruners for clean cuts — torn stems invite disease.

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.

Calhoun County, Texas is in USDA Zone 9b. The average last spring frost is February 16 and the first fall frost is December 7, giving you a growing season of approximately 294 days.

At an elevation of 215 feet, Calhoun County receives approximately 59.5 inches of rainfall annually with predominantly loam soil. Summer highs average 99°F, so Ageratum may need afternoon shade and extra watering during peak heat. 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
Calhoun County, TX (Zone 9b) Year-round
294 days
Last Spring Frost February 16
294 growing days
First Fall Frost December 7

Calhoun County Soil Profile

Soil Type

Loam

Soil pH

6.2-7.8

Drainage

Well Drained

Ageratum Planting Risk Windows

Early Start (70% safe) ✓ Fits season (94 days to spare)
Start indoors: Dec 12 Transplant: Jan 2 🌸 Bloom: Feb 27 – Aug 28
Recommended (50%) ✓ Fits season (77 days to spare)
Start indoors: Jan 5 Transplant: Jan 26 🌸 Bloom: Mar 23 – Sep 21
Safe Start (90%) ✓ Fits season (68 days to spare)
Start indoors: Jan 27 Transplant: Feb 17 🌸 Bloom: Apr 14 – Oct 13

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 Calhoun County

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

Soil pH

Your soil pH (6.2–7.8) overlaps with Ageratum's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.2%). Annual compost additions will help Ageratum.

How to Plant Ageratum

8"
Between Plants
10"
Between Rows

Succession Planting Ageratum

5
successive plantings in your 294-day season

Sow every 6.9 weeks. Last sowing by Sep 23 to harvest before frost.

Ageratum Water Budget

Plant needs
1.0″/week
Rainfall provides
0.9″/week
You supply
0.2″/week
Watering frequency Only during dry spells
Season total 401 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 1.4" 0" ❄️ Dormant
Feb 4.3" 2.2" 2.1" 💧 Light watering
Mar 4.3" 4.6" 0" ✅ Rainfall sufficient
Apr 4.3" 6.7" 0" ✅ Rainfall sufficient
May 4.3" 8.5" 0" ✅ Rainfall sufficient
Jun 4.3" 9.1" 0" ✅ Rainfall sufficient
Jul 4.3" 7.3" 0" ✅ Rainfall sufficient
Aug 4.3" 6.6" 0" ✅ Rainfall sufficient
Sep 4.3" 5.2" 0" ✅ Rainfall sufficient
Oct 4.3" 3.9" 0.4" 💧 Light watering
Nov 4.3" 2.2" 2.1" 💧 Light watering
Dec 4.3" 1.9" 2.4" 🚿 Regular watering

Water needs are for active growing months only (Feb–Dec in Calhoun 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 ~1,637 GDD — county provides 7,153 GDD Excellent fit

Ageratum Planting Timeline — Calhoun County, TX

Ageratum Planting Calendar

Activity When Date Range
Start Indoors January 5 Jan 5 – Jan 19
Transplant Outdoors January 26 Jan 26 – Feb 9
Direct Sow January 26 Jan 26 – Feb 16
Bloom March 23 Mar 23 – Sep 21

· 8" apart · Rows 10" apart

Month-by-Month Timeline

MonthActivities
January Start Indoors Transplant Outdoors Direct Sow
February Transplant Outdoors Direct Sow
March Bloom
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: acceptable

🗺️ USDA Zone

Zone 9b

📆 Growing Season

294 days in Calhoun County

Growing Tips for Ageratum in Calhoun County

Direct sow Ageratum outdoors after February 16 in Calhoun County when soil has warmed and frost danger has passed.

With summer highs reaching 99°F in Calhoun 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 Calhoun County, TX?

Calhoun County is in Zone 9b with an average last frost of February 16. Plan your Ageratum planting based on this frost date — see the calendar above for exact timing.

What planting zone is Calhoun County, TX?

Calhoun County, Texas is in USDA Hardiness Zone 9b. The average last spring frost is February 16 and first fall frost is December 7.

🌱

Your Calhoun County Garden Planner — Free

A 22-page printable planner built for Calhoun County (Zone 9b). 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 Calhoun 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.