Petunia in Zone 11a & 11b
Petunia × hybrida
Yes, petunia grows in zones 11a and 11b. Start seeds indoors Oct 30–Nov 6 and plant out Jan 15–Jan 22.
When to plant petunia in zone 11b
Zones 11a and 11b share the same average frost dates, so this page covers both.
Method: Start indoors: Start indoors from seed, then transplant outside. It needs a head start most zones can't give it by direct-sowing alone.
| Start indoors | Oct 30–Nov 6 |
|---|---|
| Direct sow / transplant outside | Jan 15–Jan 22 |
| Estimated bloom | Mar 26–Apr 2 (~70 days after transplanting) |
Spacing: 1 per square foot (square-foot-gardening spacing). Mature height: 0.5-1 ft.
Plant alongside it in zone 11b
These go outside within two weeks of petunia 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
Petunias take the longest lead time of any flower on this list. Seed goes in about 9 weeks before last frost, and it needs light to germinate, so it's surface-sown rather than buried. That long runway is the price for having sizable, blooming plants ready to set out once the weather turns: a trailing or mounding 6- to 12-inch plant covered in trumpet-shaped flowers across a wide color range.
How petunia 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.
Petunia 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 |
|---|---|---|---|
| 2a & 2b | Mar 18–Mar 25 | Jun 3–Jun 10 | Aug 12–Aug 19 |
| 3a & 3b | Mar 28–Apr 4 | Jun 13–Jun 20 | Aug 22–Aug 29 |
| 4a & 4b | Mar 13–Mar 20 | May 29–Jun 5 | Aug 7–Aug 14 |
| 5a & 5b | Mar 8–Mar 15 | May 24–May 31 | Aug 2–Aug 9 |
| 6a & 6b | Feb 21–Feb 28 | May 9–May 16 | Jul 18–Jul 25 |
| 7a & 7b | Feb 6–Feb 13 | Apr 24–May 1 | Jul 3–Jul 10 |
| 8a & 8b | Jan 21–Jan 28 | Apr 8–Apr 15 | Jun 17–Jun 24 |
| 9a & 9b | Dec 14–Dec 21 | Mar 1–Mar 8 | May 10–May 17 |
| 10a & 10bFall window | Jul–Jan | Sep–Mar | ~70 days after transplanting |
| 11a & 11b (your zone) | Oct 30–Nov 6 | Jan 15–Jan 22 | Mar 26–Apr 2 |
Bloom dates are about 70 days after the sow or plant-out date, not after starting seeds indoors.
Zone 2 sows before zone 3 here, which looks wrong and is not. USDA zones rank winter cold, not season length, and zone 2 is mostly interior Alaska, where hard winters come with warm summers. More on what a zone measures.
Good companions
No well-established companions for petunia.
Where to buy petunia seeds
Botanical Interests · True Leaf Market · Burpee (each supplier's petunia seeds)
See why we recommend these suppliers →
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See it growing
Search YouTube for "growing petunia" 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 Petunia in USDA zone 11b: when to start seeds indoors, when to direct-sow, and when to expect a bloom.
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