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When to Plant Ageratum in Stephens County, TX

Stephens County, Texas Zone 8a June

This month in Stephens County, Texas

If you only do a handful of things in the garden this June, make it these. They're sequenced around your zone's frost timing.

Avg. last frost April 4
Avg. first frost November 10
Soil temp (4") 72°F
Watering Low
Pest pressure High
Daylight 14.1 hrs
  1. Bring in the ageratum

    Check every 1–2 days. Many of these get tough or go to seed if you wait too long.

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.

Stephens County, Texas is in USDA Zone 8a. The average last spring frost is April 4 and the first fall frost is November 10, giving you a growing season of approximately 220 days.

At an elevation of 3,055 feet, Stephens County receives approximately 63.4 inches of rainfall annually with predominantly loam soil. Summer highs average 92°F, providing good warmth for Ageratum during the growing season. 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
Stephens County, TX (Zone 8a) Long season
220 days
Last Spring Frost April 4
220 growing days
First Fall Frost November 10
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Stephens County Soil Profile

Soil Type

Loam

Soil pH

6.7-7.7

Drainage

Well Drained

Ageratum Planting Risk Windows

Early Start (70% safe) ✓ Fits season (37 days to spare)
Start indoors: Feb 7 Transplant: Mar 14 🌸 Bloom: May 9 – Sep 26
Recommended (50%) ✓ Fits season (31 days to spare)
Start indoors: Feb 21 Transplant: Mar 28 🌸 Bloom: May 23 – Oct 10
Safe Start (90%) ✓ Fits season (31 days to spare)
Start indoors: Mar 5 Transplant: Apr 9 🌸 Bloom: Jun 4 – Oct 22

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 Stephens County

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

Soil pH

Your soil pH (6.7–7.7) is more alkaline than Ageratum prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.5%). Annual compost additions will help Ageratum.

How to Plant Ageratum

8"
Between Plants
10"
Between Rows

Succession Planting Ageratum

4
successive plantings in your 220-day season

Sow every 6.9 weeks. Last sowing by Aug 27 to harvest before frost.

Ageratum Water Budget

Plant needs
1.0″/week
Rainfall provides
1.2″/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 1.7" 0" ❄️ Dormant
Feb 2.3" 0" ❄️ Dormant
Mar 3.6" 0" ❄️ Dormant
Apr 4.3" 7.1" 0" ✅ Rainfall sufficient
May 4.3" 9.8" 0" ✅ Rainfall sufficient
Jun 4.3" 10.6" 0" ✅ Rainfall sufficient
Jul 4.3" 7.2" 0" ✅ Rainfall sufficient
Aug 4.3" 7.3" 0" ✅ Rainfall sufficient
Sep 4.3" 6.5" 0" ✅ Rainfall sufficient
Oct 4.3" 3.4" 0.9" 💧 Light watering
Nov 4.3" 2.1" 2.2" 🚿 Regular watering
Dec 1.6" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Nov in Stephens 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 ~1,282 GDD — county provides 4,180 GDD Excellent fit

Ageratum Planting Timeline — Stephens County, TX

Ageratum Planting Calendar

Activity When Date Range
Start Indoors February 21 Feb 21 – Mar 7
Transplant Outdoors March 28 Mar 28 – Apr 11
Direct Sow March 28 Mar 28 – Apr 18
Bloom May 23 May 23 – Oct 10

· 8" apart · Rows 10" apart

Month-by-Month Timeline

MonthActivities
January
February Start Indoors
March Start Indoors Transplant Outdoors Direct Sow
April Transplant Outdoors Direct Sow
May Bloom
June Bloom
July Bloom
August Bloom
September Bloom
October Bloom
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 8a

📆 Growing Season

220 days in Stephens County

Growing Tips for Ageratum in Stephens County

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

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 Stephens County, TX?

Stephens County is in Zone 8a with an average last frost of April 4. Plan your Ageratum planting based on this frost date — see the calendar above for exact timing.

What planting zone is Stephens County, TX?

Stephens County, Texas is in USDA Hardiness Zone 8a. The average last spring frost is April 4 and first fall frost is November 10.

🌱

Your Stephens County Garden Planner — Free

A 22-page printable planner built for Stephens County (Zone 8a). 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 Stephens 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.