Campanula (Bellflower) in Zone 6a & 6b
Campanula medium
When to plant campanula (bellflower) in zone 6b
Zones 6a and 6b 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 | Mar 7–Mar 14 |
|---|---|
| Direct sow / transplant outside | May 2–May 9 |
| Estimated bloom | Aug 30–Sep 6 (~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 6's season
Zone 6b's frost-free window runs about 173 days, from April 25 to October 15. Campanula (Bellflower) needs about 120 days from transplant to first harvest.
Good companions
No standout companions recorded yet for Campanula (Bellflower).
Where to buy campanula seeds
See why we recommend these suppliers →
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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 6b calendar · Full companion planting guide · Full plant profile · Plan your beds in the Garden Designer →

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Growing Campanula (Bellflower) in USDA zone 6b: when to start seeds indoors, when to direct-sow, and when to expect a bloom.
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