Campanula (Bellflower) in Zone 11a & 11b
Campanula medium
When to plant campanula (bellflower) in zone 11b
Zones 11a and 11b share the same average frost dates in our data, so this page covers both.
Method: Start indoors: Start indoors from seed, then transplant outside. Campanula (Bellflower) needs a head start most zones can't give it by direct-sowing alone.
| Start indoors | Nov 13–Nov 20 |
|---|---|
| Direct sow / transplant outside | Jan 8–Jan 15 |
| Estimated bloom | May 8–May 15 (~120 days after transplanting) |
Spacing: 2 per square foot (square-foot-gardening spacing). Mature height: 2.5-3.5 ft.

Campanula, also called Canterbury bells, is a tall spring cut flower with a genuine quirk: it's daylength-sensitive, needing short days as a young seedling to build enough stem length before it flowers under the long days of early summer.
How campanula (bellflower) fits zone 11's season
Zone 11b is frost-free in this dataset, so frost is not what limits the calendar here. What you can plant, and when, comes down to summer heat and daylength instead.
Good companions
No standout companions recorded yet for Campanula (Bellflower).
Where to buy campanula seeds
See why we recommend these suppliers →
As an Amazon Associate we earn from qualifying purchases. Some links on this page also go to other retailers we may earn a commission from as an affiliate, at no extra cost to you. We only recommend products with a genuine consensus of positive, independent reviews. See the sources cited on each item.
See it growing
Search YouTube for "growing campanula (bellflower)" videos → (a live search, not a hand-picked video; results vary and aren't vetted by us)
← Back to the full zone 11b calendar · Full companion planting guide · Full plant profile · Plan your beds in the Garden Designer →

Pin this for later
Growing Campanula (Bellflower) in USDA zone 11b: when to start seeds indoors, when to direct-sow, and when to expect a bloom.
Save to Pinterest