When to Plant Ageratum in USDA Zone 9b
Your August game plan for Zone 9b
If you only do a handful of things in the garden this August, make it these. They're sequenced around your zone's frost timing.
-
Bring in the ageratum
Check every 1–2 days. Many of these get tough or go to seed if you wait too long.
Before September arrives, get these ready
- First harvests: ageratum
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 9b, the average last spring frost is around January 25 and the first fall frost is around December 20, giving you a growing season of approximately 329 days.
Ageratum Planting Timeline — Zone 9b
Where Is USDA Zone 9b?
The map below highlights the states that contain Zone 9b. Click any state to see the Ageratum planting schedule for that location.
Ageratum Planting Calendar — Zone 9b
| 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 |
· 8" apart · Rows 10" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | Transplant Outdoors Direct Sow |
| February | — |
| March | Bloom |
| April | Bloom |
| May | Bloom |
| June | Bloom |
| July | Bloom |
| August | Bloom |
| September | — |
| October | — |
| November | — |
| December | Start Indoors |
Free Zone 9b Planting Calendar PDF
Know exactly when to plant every crop in your zone. Get a printable month-by-month calendar customized for Zone 9b 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
25°F to 30°F average annual minimum
Growing Season
329 days (Zone 9b average)
Planting Specifications
| Plant Spacing | 8 inches apart |
| Row Spacing | 10 inches between rows |
Succession Planting Ageratum in Zone 9b
Sow every 6.9 weeks for continuous harvest throughout the season.
Growing Tips for Ageratum in Zone 9b
Zone 9b offers a long growing season (~329 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
Good Companions
The Gardener's Encyclopedia to Companion Planting
The pairings that make vegetables, herbs, and flowers grow better — and the ones that quietly wreck a bed.
- Proven pairings for 200+ vegetables, herbs, flowers, and fruits
- Full seed-starting + planting schedule with timing and spacing
- Bonus: square-foot gardening guide + printable seasonal planners
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 9b?
In Zone 9b, plan your Ageratum planting around the average last frost date of January 25. Start seeds indoors around December 14. Direct sow outdoors around January 4. Transplant seedlings around January 4.
Can Ageratum grow in Zone 9b?
Yes, Ageratum can grow well in Zone 9b, hardy in USDA zones 3a through 11b. Zone 9b has a growing season of approximately 329 days, which is sufficient for Ageratum (60-75 days to maturity).
When can I harvest Ageratum in Zone 9b?
In Zone 9b, expect to harvest Ageratum from March 1 – August 30. Ageratum takes 60-75 days from planting to harvest.
What is the last frost date for Zone 9b?
The average last spring frost in Zone 9b is around January 25, and the first fall frost is around December 20. This gives a growing season of approximately 329 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 9b Garden Planner — Free
A 22-page printable planner tailored to Zone 9b. Planting dates, monthly task lists, harvest log, seed inventory, and succession charts — everything you need to plan a full season.