Canterbury Bells (Campanula medium) are garden plants admired for their bell-shaped flowers. These delightful blooms, often found in shades of white, pink, blue, and purple, are popular choices for cottage gardens and cut flower arrangements, adding vibrant color to any landscape.
Understanding Their Biennial Nature
Canterbury Bells are classified as biennials, meaning they complete their entire life cycle over two growing seasons. Unlike annuals that finish their cycle in one year or perennials that live for many years, biennials dedicate their first year to vegetative growth. During this initial period, they develop roots, stems, and leaves, storing energy for the display of flowers in their second year. After blooming and producing seeds in the second season, the plant dies, concluding its two-year journey.
Year One: Growth and Establishment
The first year of a Canterbury Bell’s life is focused on building a strong foundation. Whether sown directly in the garden or started indoors, seeds germinate and begin to grow. This initial growth typically results in a low-growing clump or rosette of green leaves close to the ground. No flowers will appear during this phase, as the plant is concentrating its energy on developing a robust root system and foliage. Providing conditions such as full sun to partial shade and moist, well-draining soil supports this vegetative development.
Year Two: Flowering, Seeding, and Completion
In their second year, Canterbury Bells transition from vegetative growth to their flowering phase. As spring progresses, the plant “bolts,” sending up tall, upright flower stalks. These stems become laden with the signature bell-shaped blooms, which typically appear from late spring into summer, often lasting for two to three months. After the flowering period, the plant undergoes pollination and then forms seeds. Once the seeds have matured and are dispersed, the plant completes its biological cycle, and the original plant will die.
Cultivating for Success Through Their Cycle
To ensure blooms each year, gardeners often sow seeds annually, typically in late spring or early summer. Seeds can be started indoors 6-8 weeks before the last frost or direct-sown outdoors after frost danger has passed; they require light to germinate, so press them onto the soil surface without heavy covering. Optimal planting times allow for sufficient first-year growth before winter, as young plants are more likely to thrive and flower in their second season.
During the first year, consistent moisture is important for the developing rosette of leaves, but avoid overwatering. A thick layer of mulch applied in late fall can help protect first-year plants through colder winter months. In the second year, as flower stalks emerge, the plant benefits from regular watering, especially during dry spells, and may appreciate a balanced fertilizer application in spring to support flowering. Taller varieties might require staking to prevent stems from flopping due to the weight of their blooms.
To prolong the flowering display, deadhead spent blooms. To encourage self-seeding and ensure future generations of Canterbury Bells, allow some of the flowers to remain on the plant and mature into seed pods. This allows plants to drop their seeds, potentially leading to new seedlings that continue the cycle. Maintaining a succession of plantings ensures a continuous bloom in the garden.