Clustered bellflower is well-regarded for its low-maintenance profile, making it a gardener’s delight. A key care point for clustered bellflower is to ensure well-drained soil to prevent root rot, a common issue for plants that dislike waterlogged conditions. Another important aspect is full sun to partial shade exposure, which is crucial for optimal flowering. Pruning after the first bloom can encourage a second flowering, maximizing clustered bellflower’s ornamental potential.
I. Appearance and Characteristics
Campanula glomerata, known by the common names clustered bellflower or Dane’s blood, is a species of flowering plant in the genus Campanula, belonging to the family Campanulaceae. It is the county flower of Rutland, England.
The etymology of this plant is quite intuitive: the genus Latin name (“campanula”), meaning small bell, refers to the bell-shape of the flower, while the specific name (glomerata) refers to the tight grouping of the flowers at the top of the stem.
The species is native to the North Temperate Zone of Eurasia, from Britain to Japan. In Europe it is present almost everywhere except the extreme north. In North America the plant is naturalized.
This plant can be found in forests or dry grasslands, in scrub and open woodland, in grassy but not too wet places, in the edges of woods and along the margins of roads and trails. It prefers calcareous soils, at an altitude up to 1,500 m (4,921 ft) above sea level.
Campanula glomerata is a perennial herbaceous plant growing to a height of 20–60 centimetres (7.9–23.6 in), with a maximum of 90 centimetres (35 in). The stem is simple, erect and shortly pubescent, basal leaves are petiolated, oval-lanceolate and lightly heart-shaped (cordate), while cauline leaves are lanceolate, sessile and amplexicaul. The inflorescence is formed by 15-20 sessile, actinomorphic and hermaphrodite single flowers of about 2 to 3 cm. They are in terminal racemes or in the axils of upper leaves, surrounded by an involucre of bracts. The corolla is campanulate and pubescent with five dark violet-blue or purplish-blue petals. Flowering period is from June to September.
II. How to Grow and Care
Sunlight
While the clustered bellflower is at home in a cooler environment, it does still enjoy full sun or partial shade. Because of this, make sure that your plant is placed in a location that receives some shade from the hot summer sun. If the clustered bellflower is situated in the direct summer sun, then the flowers may start to wilt after just a couple of days.
Temperature
Native to northern temperate regions, the clustered bellflower is suited to USDA hardiness zones 4-8. The plant thrives in temperatures around 16 to 18 ℃, and some varieties will survive cold temperatures down to -10 ℃. Although they prefer a cool summer, the clustered bellflower can survive in temperatures up to 26 ℃, as long as they are regularly watered. If the temperature exceeds this, then the flowers will die, and the plant may not bloom again that year.
The clustered bellflower is a flowering plant that adds a whimsical feel to many gardens across the world. Depending on the climate, it will generally bloom from the beginning of summer through to the first frost. While they are reasonably easy to care for, you will need to regularly check that they have enough water in order to prevent the delicate flowers from wilting.
Watering
Adapted to moderate climates, clustered bellflower thrives with consistent moisture, mirroring its origins where it would experience regular rainfall. This species has a preference for well-drained soil and exhibits a balanced tolerance to temporary dry spells. Watering should be maintained at once every week to sustain its health and vigor. Typically cultivated outdoors due to its robust nature, clustered bellflower is an herbaceous perennial that benefits from increased watering during its active growing season to support its lush flowering.
Soil
The optimum soil for your clustered bellflower is fertile soil with a pH of 6-8, meaning neutral to alkaline. The soil must not dry too quickly, but should still be well-draining. Because of this, soils such as loam, sand, or clay are perfect for this plant. The clustered bellflower does not like warm weather, so apply a layer of mulch to the soil in the summer. This will help to keep the soil and the roots of your plant cool and moist. The nutrients from the mulch will also encourage better growth and blooming.
Fertilizing
For optimal growth, clustered bellflower benefits from periodic feeding with balanced fertilizers, incorporating high phosphorus content to encourage abundant flowering. Spring initiation with a balanced 10-10-10 formula, transitioning to a higher phosphorus ratio (10-20-10) before the blooming phase, ensures robust health. Apply every 4-6 weeks, adhering to the product’s recommended rates, avoiding over-fertilization to prevent root burn. In fall, reduce frequency as clustered bellflower’s growth naturally slows, focusing on building root reserves for winter. Always water clustered bellflower thoroughly post-fertilization to assist nutrient absorption and minimize potential toxicity.
Pruning
The typical clustered bellflower will usually grow up to 1 m and reach an ultimate spread of 1 m. They are perennial, which means that they will bloom once a year. Because of this, they do not necessarily need pruning, unless you are trying to maintain a certain shape. The clustered bellflower can take up to 5 years to reach its ultimate height, which is another reason why you may not need to prune your plant for quite a few years.
If you choose to prune for shape and to encourage growth, you should do this at the end of spring, and definitely before the beginning of fall. While pruning, remove any shoots that appear weak or are growing in the wrong direction. This will encourage the plant’s energy to be diverted towards the other shoots instead. During the flowering season, some choose to remove wilted flowers, as this can prolong the flowering phase. This can be done by ‘plucking’ off the dead flowers. Deadheading flowers will also prevent this plant from self-seeding.
Propagation
The clustered bellflower can be propagated through division, planting seeds, or basal cuttings. Most choose division because the plant should be divided every five years anyway, in order to keep it growing strong and healthy, with propagating by division being easy to do. In the spring, dig up your clustered bellflower and tease the roots apart. Then, gently cut the plant in half. Afterward, plant your clustered bellflower in nutrient-rich soil immediately, lightly packing the soil around the plant before watering it. It is best to divide your clustered bellflower on a cool day.
If you choose to plant seeds, simply sow them into nutrient-rich soil at the beginning of spring, after the last frost. Cover the ground with mulch to help the seeds germinate, and you should start to see shoots in the next 4-8 weeks. Be aware that the seeds for the clustered bellflower are cold shooters, so they must be kept at a low temperature before planting to prevent them from driving out too early.
Transplanting
To successfully transplant a clustered bellflower, choose the optimal time of early to mid-spring as the plant awakens from dormancy. This perennial thrives in partial to full sun locations, and well-draining soil is crucial. Be gentle with the roots during transplant to ensure healthy growth.
Repotting
Repot clustered bellflower every 2-3 years in spring to accommodate its moderately expansive roots and encourage its bush-like growth. Choose a slightly larger pot to facilitate the clustered purple flowers without oversizing. After repotting, gently firm the soil and keep it moist to support recovery. A sunny spot will help clustered bellflower thrive post-transplant, ensuring it blossoms year after year.
Pests and Diseases
This plant doesn’t face extreme diseases or pests problems.
However, be on a lookout for snails, slugs, and mealybugs.
The plant may get affected by leaf spots and rust.
Moreover, an overly moist condition in humid climates leads to powdery mildew.
III. Uses and Benefits
Clustered bellflower is a beautiful, easy-to-grow enhancement to add a splash of purple to a garden. Its multiple bloom stalks and rapid spread provide excellent borders. It also grows well in outdoor containers or rock gardens. Combine with other Bellflower species for added color interest.
