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When to Plant Ageratum in Roberts County, TX

Roberts County, Texas Zone 7a June

What to do in June

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 17
Avg. first frost October 24
Soil temp (4") 76°F
Watering High
Pest pressure High
Daylight 14.4 hrs
  1. Pick ageratum

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

A few tasks this June that'll pay off in 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.

Roberts County, Texas is in USDA Zone 7a. The average last spring frost is April 17 and the first fall frost is October 24, giving you a growing season of approximately 190 days.

At an elevation of 1,068 feet, Roberts County receives approximately 51 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 98°F, so Ageratum may need afternoon shade and extra watering during peak heat. Sandy soil warms quickly in spring — great for early planting — but Ageratum will need more frequent watering and organic matter to retain nutrients. 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
Roberts County, TX (Zone 7a) Moderate season
190 days
Last Spring Frost April 17
190 growing days
First Fall Frost October 24
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Roberts County Soil Profile

Soil Type

Sandy Loam

Soil pH

7.5-8.8

Drainage

Well Drained

Ageratum Planting Risk Windows

Early Start (70% safe) ✓ Fits season (21 days to spare)
Start indoors: Feb 28 Transplant: Apr 11 🌸 Bloom: Jun 6 – Sep 26
Recommended (50%) ✓ Fits season (22 days to spare)
Start indoors: Mar 6 Transplant: Apr 17 🌸 Bloom: Jun 12 – Oct 2
Safe Start (90%) ✓ Fits season (19 days to spare)
Start indoors: Mar 21 Transplant: May 2 🌸 Bloom: Jun 27 – Oct 17

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 Roberts County

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

Soil pH

Your soil pH (7.5–8.8) is more alkaline than Ageratum prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

Sandy soil in Roberts County warms quickly in spring but drains fast. Ageratum will need more frequent watering and regular compost additions to retain nutrients.

Organic Matter

Organic matter is low (0.9%). Add 2-3 inches of compost before planting Ageratum.

How to Plant Ageratum

8"
Between Plants
10"
Between Rows

Succession Planting Ageratum

3
successive plantings in your 190-day season

Sow every 6.9 weeks. Last sowing by Aug 10 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
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 3.5" 0" ❄️ Dormant
Feb 3.3" 0" ❄️ Dormant
Mar 2.9" 0" ❄️ Dormant
Apr 4.3" 1.9" 2.4" 🚿 Regular watering
May 4.3" 1.1" 3.2" 🚿 Regular watering
Jun 4.3" 1.5" 2.8" 🚿 Regular watering
Jul 4.3" 9.3" 0" ✅ Rainfall sufficient
Aug 4.3" 9.5" 0" ✅ Rainfall sufficient
Sep 4.3" 6.3" 0" ✅ Rainfall sufficient
Oct 4.3" 5" 0" ✅ Rainfall sufficient
Nov 3.3" 0" ❄️ Dormant
Dec 3.3" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Roberts 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 ~1,586 GDD — county provides 4,465 GDD Excellent fit

Ageratum Planting Timeline — Roberts County, TX

Ageratum Planting Calendar

Activity When Date Range
Start Indoors March 6 Mar 6 – Mar 20
Transplant Outdoors April 17 Apr 17 – May 1
Direct Sow April 17 Apr 17 – May 8
Bloom June 12 Jun 12 – Oct 2

· 8" apart · Rows 10" apart

Month-by-Month Timeline

MonthActivities
January
February
March Start Indoors
April Transplant Outdoors Direct Sow
May Transplant Outdoors Direct Sow
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 7a

📆 Growing Season

190 days in Roberts County

Growing Tips for Ageratum in Roberts County

Direct sow Ageratum outdoors after April 17 in Roberts County when soil has warmed and frost danger has passed.

Sandy soil in Roberts County dries quickly — mulch Ageratum with 2-3 inches of straw and water deeply 2-3 times per week rather than lightly every day.

With summer highs reaching 98°F in Roberts 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 Roberts County, TX?

Roberts County is in Zone 7a with an average last frost of April 17. Plan your Ageratum planting based on this frost date — see the calendar above for exact timing.

What planting zone is Roberts County, TX?

Roberts County, Texas is in USDA Hardiness Zone 7a. The average last spring frost is April 17 and first fall frost is October 24.

🌱

Your Roberts County Garden Planner — Free

A 22-page printable planner built for Roberts County (Zone 7a). 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 Roberts 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.