When to plant Bellflower?
Best month and method — Campanula persicifolia
Plant your bellflower in March, April, May, September and October — the optimal month is usually May.
You're in the planting season right now — a good moment to start.

Spacing
30 cm
≈ 11 plants
For an X m² border, calculate: X × 11 plants.
Step by step: plant bellflower
Campanula persicifolia thrives in full sun or partial shade, making it a versatile choice for borders and cottage-garden schemes. It performs best in well-drained loam or chalky soil with good structure. Before planting, dig over the site to a spade's depth and work in a generous amount of garden compost or well-rotted manure to improve drainage and fertility, especially if your soil is heavy clay. Plant container-grown bellflowers in March, April or May for establishment before summer, or in September and October for autumn planting. Dig a hole slightly wider than the root ball and set the plant at the same depth it was growing in its pot. Space plants 30 cm apart to allow for their mature spread of 25–40 cm and to ensure good air circulation, which helps prevent mildew. After planting, firm the soil gently around the roots and water thoroughly to settle the plant in. Apply a 5 cm layer of mulch such as garden compost or bark chips around the base, keeping it clear of the crown to avoid rot. This helps retain moisture and suppress weeds while the plant establishes. Water regularly during the first growing season, especially in dry spells, to encourage a strong root system. Campanula persicifolia is fully hardy to zone 3a, so no winter protection is needed in temperate European climates. The plants will develop a clump of narrow, evergreen basal leaves and send up tall flower spikes reaching 40–90 cm in early summer. Avoid planting in waterlogged sites, as bellflowers resent sitting in wet soil over winter.