Dahlia in Zone 11a & 11b
Dahlia spp.
Yes, dahlia grows in zones 11a and 11b. Plant it outside Jan 15–Jan 22.
When to plant dahlia in zone 11b
Zones 11a and 11b share the same average frost dates, so this page covers both.
Method: Direct sow: Direct-sow outside. It doesn't transplant well, or doesn't need the extra time indoors.
| Start indoors | Not typically started indoors |
|---|---|
| Direct sow / transplant outside | Jan 15–Jan 22 |
| Estimated bloom | Apr 15–Apr 22 (~90 days after direct-sowing) |
Spacing: 1 per square foot (square-foot-gardening spacing). Mature height: 1-5 ft.
Plant alongside it in zone 11b
These go outside within two weeks of dahlia in zone 11b, so one planting day can cover them.
- NasturtiumJan 8–Jan 15
- MarigoldJan 8–Jan 15
- Angelonia (Summer Snapdragon)Jan 15–Jan 22
- Black-Eyed Susan VineJan 15–Jan 22
- Cleome (Spider Flower)Jan 15–Jan 22
- ColeusJan 15–Jan 22
Dahlia is the one flower in this garden that doesn't start as seed at all. It grows from a tuber, planted like a potato, which changes the whole rhythm of how it goes in the ground and comes out at season's end. Blooms run from small pompoms to dinner-plate-sized flower heads, in nearly every color except true blue, on plants that range from 1 to 5 feet depending on type.
How dahlia fits zone 11's season
Zone 11b is frost-free, so frost is not what limits the calendar here. What you can plant, and when, comes down to summer heat and daylength instead.
Dahlia planting windows in every zone
Zone 11b is highlighted. Useful for comparing against a neighbouring zone, or for a garden somewhere else.
| Zone | Start indoors | Sow or plant out | Bloom |
|---|---|---|---|
| 3a & 3b | Not usually | Jun 13–Jun 20 | Sep 11–Sep 18 |
| 4a & 4b | Not usually | May 29–Jun 5 | Aug 27–Sep 3 |
| 5a & 5b | Not usually | May 24–May 31 | Aug 22–Aug 29 |
| 6a & 6b | Not usually | May 9–May 16 | Aug 7–Aug 14 |
| 7a & 7b | Not usually | Apr 24–May 1 | Jul 23–Jul 30 |
| 8a & 8b | Not usually | Apr 8–Apr 15 | Jul 7–Jul 14 |
| 9a & 9b | Not usually | Mar 1–Mar 8 | May 30–Jun 6 |
| 10a & 10bSpring window | Not usually | Feb–Apr | ~90 days after direct-sowing |
| 11a & 11b (your zone) | Not usually | Jan 15–Jan 22 | Apr 15–Apr 22 |
Bloom dates are about 90 days after the sow or plant-out date.
Good companions
No well-established companions for dahlia.
Where to buy dahlia bulbs
We haven't vetted bulb/tuber suppliers yet. Our seed-supplier list below doesn't carry these. The growing-guide source cited above is a good starting point for where to buy.
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See it growing
Search YouTube for "growing dahlia" videos → (a live search, not a hand-picked video; results vary and aren't vetted by us)
← Back to the full zone 11b calendar · Plan your beds in the Garden Designer →
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Growing Dahlia in USDA zone 11b: when to start seeds indoors, when to direct-sow, and when to expect a bloom.
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