Canterbury Bells (Campanula medium) are charming, bell-shaped flowers that bring a classic touch to garden spaces. Their vibrant colors, ranging from white to pink, purple, and blue, make them a favored choice for many gardeners. This guide provides information on cultivating these beautiful plants for a thriving and continuous display.
Canterbury Bells Basics
Canterbury Bells are biennials, completing their life cycle over two years. The first year develops foliage and roots, with blooms appearing in the second. For continuous blooms, new plants should be started annually.
Planting Canterbury Bells can occur in either fall or spring. If starting from seed, indoor sowing in late winter is an option, with seedlings transplanted outdoors after the last frost. For optimal growth and prolific flowering, Canterbury Bells prefer full sun (at least six hours daily), though partial shade may result in less vibrant blooms. Adequate spacing (12 to 18 inches) is important for good air circulation, preventing overcrowding and supporting healthy growth.
Optimal Growing Environment
Canterbury Bells thrive in well-draining soil that is rich in organic matter. A slightly alkaline to neutral pH, ideally between 6.5 and 7.5, is preferred. Incorporating compost or other organic materials improves soil aeration and water retention.
Consistent moisture is important for these plants, so regular watering is necessary during the growing season. The soil should remain evenly moist but never waterlogged, as this can lead to root rot. Watering deeply once a week, especially during dry spells, is generally sufficient. Mulching around the base of the plants helps retain soil moisture and can reduce the frequency of watering.
Canterbury Bells prefer cooler climates and moderate temperatures, thriving in USDA hardiness zones 4-8. While they can tolerate temperatures up to 26°C with regular watering, prolonged periods above 26°C can negatively affect flowering. In hot summers, providing some afternoon shade can help protect the plants from intense heat.
Routine Care and Maintenance
Fertilizing Canterbury Bells supports vigorous growth and abundant flowering. Apply a balanced fertilizer (e.g., a 10-10-10 NPK blend) in early spring as new growth begins, with a second light application just before budding to boost blooms. Over-fertilizing, particularly with high-nitrogen formulas, should be avoided as it can promote excessive foliage at the expense of flowers.
Deadheading spent blooms is a beneficial practice that encourages more flowers and extends the blooming period by redirecting the plant’s energy from seed production. This also helps maintain a tidy appearance and prevents premature self-seeding if not desired. Removing any diseased or damaged foliage further contributes to plant health and vigor.
Addressing Common Issues
While generally robust, Canterbury Bells can occasionally encounter issues. Fungal diseases such as powdery mildew and rust may appear as discoloration or lesions on leaves. Good air circulation, achieved through proper plant spacing and selective thinning of crowded stems, helps prevent these. Watering the plants at soil level rather than on the foliage also reduces the risk of fungal problems.
Pests like aphids and slugs can affect Canterbury Bells. Aphids, small insects that cluster on new growth, can be dislodged with a strong spray of water or treated with insecticidal soap. Slugs and snails may munch on young foliage; barriers or bait can help manage their presence. Wilting can indicate improper watering, emphasizing the need for consistent moisture without waterlogging.
Ensuring Future Blooms
Encouraging Canterbury Bells to self-seed is a practical way to ensure continuous blooms. Allow some spent flowers to remain, enabling natural seed production and dropping. This creates a succession of plants, with new rosettes forming in the first year to bloom in the second.
Alternatively, collect seeds once pods turn brown and dry, storing them for spring planting. For first-year plants in colder climates, provide overwintering care. A thick layer of mulch around the base protects the crown and roots from freezing, allowing the plant to survive winter and bloom in its second year.