When to Plant Ageratum in Washington County, VT
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.
Washington County, Vermont is in USDA Zone 5a. The average last spring frost is May 12 and the first fall frost is October 7, giving you a growing season of approximately 148 days.
At an elevation of 959 feet, Washington County receives approximately 41.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 80°F, so choose short-season varieties of Ageratum to ensure they mature before fall.
Washington County Soil Profile
Soil Type
Silt Loam
Soil pH
6.0-7.0
Drainage
Well Drained
Ageratum Planting Timeline — Washington County, VT
Ageratum Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 24 | Mar 24 – Apr 7 |
| Transplant Outdoors | May 19 | May 19 – Jun 2 |
| Direct Sow | May 19 | May 19 – Jun 9 |
| Bloom | July 14 | Jul 14 – Oct 6 |
· 8" apart · Rows 10" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Start Indoors |
| May | Transplant Outdoors Direct Sow |
| June | Transplant Outdoors Direct Sow |
| July | Bloom |
| August | Bloom |
| September | Bloom |
| October | Bloom |
| 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 5a
📆 Growing Season
148 days in Washington County
Growing Tips for Washington 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
Check more plant combinations with our Companion Planting Checker →
Ageratum in Other Locations
Frequently Asked Questions
When should I plant Ageratum in Washington County, VT?
Washington County is in Zone 5a with an average last frost of May 12. Plan your Ageratum planting based on this frost date — see the calendar above for exact timing.
What planting zone is Washington County, VT?
Washington County, Vermont is in USDA Hardiness Zone 5a. The average last spring frost is May 12 and first fall frost is October 7.
Your Washington County Garden Planner — Free
A 22-page printable planner built for Washington County (Zone 5a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.