How to Grow and Care for Canterbury Bells

Canterbury bells, with the botanical name Campanula medium, are cherished for their large, bell-shaped flowers and classic presence in cottage gardens. The blooms, which can be pink, blue, white, or purple, grow on tall, upright stems and are known for their sweet fragrance. This plant is a biennial, a term that describes its two-year life cycle.

Essential Growing Conditions

Light

For the most abundant blooms, Canterbury bells should be planted in a location that receives full sun, which means about six hours of direct sunlight each day. They can grow in partial shade, but the flowering may not be as prolific. In regions with high summer heat, providing some afternoon shade is beneficial to protect the plants from intense sun and heat stress.

Soil

Canterbury bells perform best in well-draining soil that is loamy or sandy. While they can tolerate a range of soil pH levels, a neutral to slightly alkaline environment is ideal. The soil should be kept consistently moist but never waterlogged, as poor drainage can lead to root problems. Amending the garden bed with organic matter can improve both fertility and drainage.

Water

Consistent moisture is important for these plants, especially during their active growing season and any dry periods. The soil should be watered regularly to keep it evenly moist, but it is important to avoid overwatering. A layer of mulch can be applied around the base of the plants to help retain soil moisture and keep the roots cool.

Fertilizer

To support their growth and flowering, Canterbury bells benefit from fertilization. A balanced, all-purpose liquid fertilizer can be applied in the late spring of their second year to encourage new growth. Alternatively, a low-nitrogen fertilizer, such as a 5-10-5 NPK formula, can be used in the spring as new growth appears.

Pruning and Deadheading

Maintenance practices like pruning and deadheading can help prolong the blooming period of Canterbury bells. Deadheading prevents the plant from directing its energy toward seed production. To deadhead, simply pinch or cut off the spent blooms just below the flower head. This encourages the plant to produce more flowers, extending its display. Light pruning can remove dead foliage to keep the plant tidy, and for taller varieties, cutting back stems promotes a bushier growth habit.

Overwintering Care

In the first year, the plant develops a low-growing clump of leaves called a rosette. This rosette must survive the winter to produce flowers in the second year. To protect this first-year growth, it is helpful to apply a thick layer of mulch, such as straw or pine needles, over the plants after the first hard frost. This layer of insulation shields the rosette from harsh winter temperatures and freezing conditions. In the spring of the second year, the mulch can be removed as the weather warms and the plant begins to send up its flowering stalks.

Managing Common Issues

Canterbury bells can sometimes face issues with pests and diseases. Slugs, snails, and aphids are common pests that may appear on the leaves and tender foliage. Fungal diseases such as powdery mildew and rust can also affect the plants, especially in humid conditions with poor air circulation. Ensuring good air circulation by properly spacing plants and pruning when needed can help prevent these fungal problems. In many cases, removing affected leaves can help manage the spread of disease.