When to Plant Ageratum in USDA Zone 10a
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.
In Zone 10a, the average last spring frost is around January 1 and the first fall frost is around December 31, giving you a growing season of approximately 364 days.
Ageratum Planting Timeline — Zone 10a
Where Is USDA Zone 10a?
The map below highlights the states that contain Zone 10a. Click any state to see the Ageratum planting schedule for that location.
Ageratum Planting Calendar — Zone 10a
| 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 |
· 8" apart · Rows 10" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | Bloom |
| February | Bloom |
| March | Bloom |
| April | Bloom |
| May | Bloom |
| June | Bloom |
| July | Bloom |
| August | Bloom |
| September | — |
| October | — |
| November | Start Indoors Transplant Outdoors Direct Sow |
| December | Start Indoors Transplant Outdoors Direct Sow |
Free Zone 10a Planting Calendar PDF
Know exactly when to plant every crop in your zone. Get a printable month-by-month calendar customized for Zone 10a with start dates, transplant windows, and harvest times.
Growing Conditions
Sun
Full Sun (6-8+ hours)
💧 Water
Moderate — regular watering
Days to Maturity
60–75 days
Soil pH
6 – 7
Zone Temperature Range
30°F to 35°F average annual minimum
Growing Season
365 days (Zone 10a average)
Planting Specifications
| Plant Spacing | 8 inches apart |
| Row Spacing | 10 inches between rows |
Succession Planting Ageratum in Zone 10a
Sow every 6.9 weeks for continuous harvest throughout the season.
Growing Tips for Ageratum in Zone 10a
Zone 10a offers a long growing season (~365 days). You can plant Ageratum earlier and may get multiple harvests.
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
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Saving Ageratum Seeds
Recommended for Your Garden
Reduce heat stress and sun scorch in hot climates with UV-stabilized shade cloth.
Start seeds indoors with reusable cell trays and humidity domes.
Test your soil pH, nitrogen, phosphorus, and potassium levels before planting.
Related Plants
Ageratum in Other Zones
Ageratum by State
- Alabama
- Alaska
- Arizona
- Arkansas
- California
- Colorado
- Connecticut
- Delaware
- Florida
- Georgia
- Hawaii
- 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 Zone 10a?
In Zone 10a, plan your Ageratum planting around the average last frost date of January 1. Start seeds indoors around November 20. Direct sow outdoors around November 27. Transplant seedlings around November 27.
Can Ageratum grow in Zone 10a?
Yes, Ageratum can grow well in Zone 10a, hardy in USDA zones 3a through 11b. Zone 10a has a growing season of approximately 364 days, which is sufficient for Ageratum (60-75 days to maturity).
When can I harvest Ageratum in Zone 10a?
In Zone 10a, expect to harvest Ageratum from January 22 – August 6. Ageratum takes 60-75 days from planting to harvest.
What is the last frost date for Zone 10a?
The average last spring frost in Zone 10a is around January 1, and the first fall frost is around December 31. This gives a growing season of approximately 364 days. These are 50% probability dates — actual frost dates vary year to year.
What should I plant next to Ageratum?
Good companion plants for Ageratum include Marigolds, Zinnias, Petunias, Salvia. These companions can help with pest control, pollination, and nutrient sharing.
Your Zone 10a Garden Planner — Free
A 22-page printable planner tailored to Zone 10a. Planting dates, monthly task lists, harvest log, seed inventory, and succession charts — everything you need to plan a full season.