When to Plant Ageratum in California

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.

California spans USDA hardiness zones 10a, 10b, 6b, 7a, 7b, 8a, 8b, 9a, 9b (with planting data available), so planting dates vary by your location within the state. Click your zone below for the most accurate dates.

Find Your County

Click your county for exact Ageratum planting dates based on your local frost dates.

Hover over a county to see details. Click to view planting guide.

Ageratum Planting Calendar for California

▸ Zone 10a ~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 27	Nov 27 – Dec 11
Direct Sow	November 27	Nov 27 – Dec 18
Bloom	January 22	Jan 22 – Aug 6

▸ Zone 10b ~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 20	Nov 20 – Dec 4
Direct Sow	November 20	Nov 20 – Dec 11
Bloom	January 15	Jan 15 – Aug 13

▸ Zone 6b ~205 day growing season · Full guide →

Last frost: April 3 · First frost: October 25 · 205 day season

Activity	When	Date Range
Start Indoors	February 13	Feb 13 – Feb 27
Transplant Outdoors	April 3	Apr 3 – Apr 17
Direct Sow	April 3	Apr 3 – Apr 24
Bloom	May 29	May 29 – Sep 11

▸ Zone 7a ~221 day growing season · Full guide →

Last frost: March 25 · First frost: November 1 · 221 day season

Activity	When	Date Range
Start Indoors	February 11	Feb 11 – Feb 25
Transplant Outdoors	March 25	Mar 25 – Apr 8
Direct Sow	March 25	Mar 25 – Apr 15
Bloom	May 20	May 20 – Sep 9

▸ Zone 7b ~235 day growing season · Full guide →

Last frost: March 18 · First frost: November 8 · 235 day season

Activity	When	Date Range
Start Indoors	February 4	Feb 4 – Feb 18
Transplant Outdoors	March 18	Mar 18 – Apr 1
Direct Sow	March 18	Mar 18 – Apr 8
Bloom	May 13	May 13 – Sep 16

▸ Zone 8a ~255 day growing season · Full guide →

Last frost: March 8 · First frost: November 18 · 255 day season

Activity	When	Date Range
Start Indoors	January 25	Jan 25 – Feb 8
Transplant Outdoors	March 1	Mar 1 – Mar 15
Direct Sow	March 1	Mar 1 – Mar 22
Bloom	April 26	Apr 26 – Sep 13

▸ Zone 8b ~276 day growing season · Full guide →

Last frost: February 25 · First frost: November 28 · 276 day season

Activity	When	Date Range
Start Indoors	January 14	Jan 14 – Jan 28
Transplant Outdoors	February 11	Feb 11 – Feb 25
Direct Sow	February 11	Feb 11 – Mar 4
Bloom	April 8	Apr 8 – Sep 9

▸ Zone 9a ~303 day growing season · Full guide →

Last frost: February 10 · First frost: December 10 · 303 day season

Activity	When	Date Range
Start Indoors	December 30	Dec 30 – Jan 13
Transplant Outdoors	January 27	Jan 27 – Feb 10
Direct Sow	January 27	Jan 27 – Feb 17
Bloom	March 24	Mar 24 – Sep 8

▸ Zone 9b ~329 day growing season · Full guide →

Last frost: January 25 · First frost: December 20 · 329 day season

Activity	When	Date Range
Start Indoors	December 14	Dec 14 – Dec 28
Transplant Outdoors	January 4	Jan 4 – Jan 18
Direct Sow	January 4	Jan 4 – Jan 25
Bloom	March 1	Mar 1 – Aug 30

Growing Tips for California

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

Frequently Asked Questions

When should I plant Ageratum in California?

Planting dates for Ageratum in California depend on your USDA zone. California spans zones 10a, 10b, 6b, 7a, 7b, 8a, 8b, 9a, 9b. Check the planting calendar above for your specific zone's frost dates and planting windows.

What zone is California for planting?

California contains USDA hardiness zones 10a, 10b, 6b, 7a, 7b, 8a, 8b, 9a, 9b. 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.

Blog