When to Plant Ageratum in Hawaii
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.
Hawaii spans USDA hardiness zones 11a (with planting data available), so planting dates vary by your location within the state. Click your zone below for the most accurate dates.
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Ageratum Planting Calendar for Hawaii
▸ Zone 11a ~364 day growing season · Full guide →
Last frost: January 1 · First frost: December 31 · 364 day season
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | November 20 | Nov 20 – Dec 4 |
| Transplant Outdoors | November 6 | Nov 6 – Nov 20 |
| Direct Sow | November 6 | Nov 6 – Nov 27 |
| Bloom | January 1 | Jan 1 – Aug 13 |
Growing Tips for Hawaii
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.
Ageratum in Other States
- Alabama
- Alaska
- Arizona
- Arkansas
- California
- Colorado
- Connecticut
- Delaware
- Florida
- Georgia
- Idaho
- Illinois
- Indiana
- Iowa
- Kansas
- Kentucky
- Louisiana
- Maine
- Maryland
- Massachusetts
- Michigan
- Minnesota
- Mississippi
- Missouri
- Montana
- Nebraska
- Nevada
- New Hampshire
- New Jersey
- New Mexico
- New York
- North Carolina
- North Dakota
- Ohio
- Oklahoma
- Oregon
- Pennsylvania
- Rhode Island
- South Carolina
- South Dakota
- Tennessee
- Texas
- Utah
- Vermont
- Virginia
- Washington
- West Virginia
- Wisconsin
- Wyoming
Frequently Asked Questions
When should I plant Ageratum in Hawaii?
Planting dates for Ageratum in Hawaii depend on your USDA zone. Hawaii spans zones 11a. Check the planting calendar above for your specific zone's frost dates and planting windows.
What zone is Hawaii for planting?
Hawaii contains USDA hardiness zones 11a. Your specific zone depends on your location within the state — northern and higher-elevation areas are in colder zones, while southern and coastal areas are warmer.