Grow Campanula plants by planting them in sites with full or partial sun and well-drained soil, keeping the soil moist but not damp, and fertilizing them every spring. After the plants bloom, snip off the faded blooms to increase flowering.
Depending on the variety of the Campanula plant and the climate, plant it either in full or partial sun. Campanulas in hot southern climes need light shade in order to thrive. Use well-drained soil with a neutral pH. Keep the soil moist by adding a layer of mulch in mid-spring or summer and watering the plant regularly during dry weather. Make sure that the mulch doesn't come in contact with the crown of the plant, as this can cause rotting.
In the early spring, feed the plant a balanced fertilizer or work compost into the soil. Watch out for any aphid infections, and treat any signs immediately with insecticidal soap. If the plant shows signs of fungal growth or rot, amend the soil with sand or perlite to improve drainage.
Snip off faded blooms as far as 2 inches down the stem to encourage flowering. Prune certain varieties back to within a few inches from the soil in the fall. Because Campanula carpatica, persicifolia and poscharskyana are sensitive to the cold, leave the lower foliage to protect the roots.