When to Plant Ageratum in Rockwall County, TX
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.
Rockwall County, Texas is in USDA Zone 8b. The average last spring frost is March 9 and the first fall frost is November 20, giving you a growing season of approximately 256 days.
At an elevation of 74 feet, Rockwall County receives approximately 71.3 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.
Rockwall County Soil Profile
Soil Type
Clay
Soil pH
6.0-7.0
Drainage
Well Drained
Ageratum Planting Timeline — Rockwall County, TX
Ageratum Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | January 26 | Jan 26 – Feb 9 |
| Transplant Outdoors | February 23 | Feb 23 – Mar 9 |
| Direct Sow | February 23 | Feb 23 – Mar 16 |
| Bloom | April 20 | Apr 20 – Sep 21 |
· 8" apart · Rows 10" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| 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 | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
Moderate — regular watering
📅 Days to Maturity
60–75 days
🧪 Soil pH
Needs 6–7 · Your soil: N/A
🗺️ USDA Zone
Zone 8b
📆 Growing Season
256 days in Rockwall County
Growing Tips for Rockwall County
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
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Ageratum in Other Locations
Frequently Asked Questions
When should I plant Ageratum in Rockwall County, TX?
Rockwall County is in Zone 8b with an average last frost of March 9. Plan your Ageratum planting based on this frost date — see the calendar above for exact timing.
What planting zone is Rockwall County, TX?
Rockwall County, Texas is in USDA Hardiness Zone 8b. The average last spring frost is March 9 and first fall frost is November 20.
Your Rockwall County Garden Planner — Free
A 22-page printable planner built for Rockwall County (Zone 8b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.