key growing information

How to Grow Campanula (Bellflower) From Seed

How to grow campanula (Canterbury bells) for cut flowers: starting plugs, light and moisture for germination, day length, sowing season, spacing and harvest.

By Hensley’s Seed Co. September 3, 2026

Campanula (Bellflower) - Key Growing Information

Campanula flowers, also known as bellflower and Canterbury bells.

DAYS TO GERMINATION:

Expect 7–14 days at 65–68°F (18–20°C).

SOWING:

Starting transplants is recommended: sow into 128-cell plug flats or your usual seedling containers 6–8 weeks before planting out. Seed needs light to germinate, but a very thin dusting of vermiculite or mix over it holds in moisture and helps the pellet coating break down. Water from below or mist gently so seed and mix aren't washed around. Direct sowing isn't advised. NOTE: start plants in fall, winter or early spring. Campanula responds to day length: seedlings need short days to build enough stem length and leafy growth before long days trigger flowering. In unheated Zone 5 tunnel trials, fall-sown plants came through winter well and bloomed in early June on very tall, vigorous stems, while winter-sown plants bloomed from mid-June into early July on shorter stems.

LIGHT PREFERENCE:

Full sun, with some tolerance for part shade.

PLANT HEIGHT:

30–40".

PLANT SPACING:

For single-stem cuts, 4–6" apart; for branched, multi-stem plants, 10–12". Staking or netting is recommended. Single-stem crops finish faster and suit greenhouse growing, while multi-stem plantings fit outdoor beds where space is less limited. Expect about 8–10 stems per plant.

HARDINESS ZONES:

Grown as an annual.

HARVEST:

For fresh use, cut when 2–3 of the lowest buds on the stem have opened, and keep stems upright afterward so they don't bend.

SOIL REQUIREMENTS:

Full sun to part shade in well-drained soil rich in organic matter; pH 5.8–6.2 is ideal.

USES:

A first-rate cut flower.

SCIENTIFIC NAME:

Campanula medium