Growing Campanula Glomerata Plants: Caring For Cluster Bellflower

Campanula Glomerata [Kam-PAN-yoo-luh, Glahm-er-AH-tuh] is a flowering species in the Campanula plant (bellflower) genus, belong to the family Campanulaceae. 

This plant is native to North America, Europe, and Asia.

Purple cluster flower - Campanula Glomerata

The common names for Campanula Glomerata include:

  • Clustered Bellflower
  • Bellflower
  • Dane’s Blood

Campanula Glomerata Plants Care

Size & Growth

The Campanula Glomerata ‘superba’ is a herbaceous perennial plant with a foliage color of green leaves, which look striking with its violet-blue flowers. 

The plant grows 8” – 24” inches tall and 35” inches wide.

The stems of the plant are short pubescent, erect, and simple. 

The basal leaves are ovate and slightly heart-shaped. 

It creates a knee-high cluster of coarse stems and basal leaves.

Flowering and Fragrance

The Clustered Bellflower produces dense large bell-shaped, deep purple flowers in early summer. 

These upward facing flowers are formed in clusters on top of stems, as high as 12” – 18” inches tall. 

The typical bloom time of this plant is between late spring and summer.

Light & Temperature

This plant tolerates partial shade during the afternoon but grows best when placed under the full sun. 

The higher amount of direct sunlight results in a higher amount of blooms. 

Provide some shade during the hot summers.

Cooler nights and warmer days are suited best for this plant. 

These plants, including Campanula Glomerata ‘Superba’, don’t flair well when growing in tropical, hot climates or when the temperature goes below 50° degrees Fahrenheit (10° C) at nighttime.

The USDA zones of hardiness for this plant are 3 – 8.

Watering and Feeding

The new plants require daily watering for the initial weeks. 

Once the plant establishes, the water needs should be adjusted to every three days, or as per the weather conditions and soil moisture. 

The different soil types hold varying levels of moisture for a specific time period; therefore, adjust the watering accordingly.

Let the soil dry out between waterings. 

However, avoid letting the soil dry out completely or overwatering the plant. 

It is ideal to water at soil level in order to avoid getting the foliage too wet.

Use balanced fertilizer twice a year, particularly in the spring and summer seasons. 

After fertilizing, thoroughly water the plant. 

Add organic compost to the plant twice every year for stronger growth.

Soil & Transplanting

The Campanula Glomerata var. easily grows in well-draining, moist soils under part shade to full sun. 

The ideal soil pH level for this plant is between 6 and 8. 

However, it prefers a slightly alkaline soil.

Provide it with a mixture with an equal amount of compost and soil to prolong its health and longevity, as well as more flowers.  

Grooming and Maintenance

The Clustered Bellflower requires regular moisture to grow optimally. Remove spent flowers immediately for additional bloom. 

During the fall season, clumps may be divided every three to five years to control or maintain the spread.

For over-wintering, cut back the plants to 3” inches during the late fall season, while adding an organic mulch layer on top of the plant. 

If the climate is mild, there isn’t a need for the mulch layer.

How to Propagate Cluster Bellflower

The propagation of Dane’s Blood is done using seeds, basal cuttings, and division in late spring.

When propagating through seeds:

  • Sow them in a cold frame to start the germination process, which typically takes about two to four weeks to complete. 
  • Once the plant grows big enough to handle easily, the seedlings must be pricked in individual containers or pots. 
  • Keep growing them in cold frames throughout their first winter. 
  • Move them to their permanent spots after the last frost.

For basal cuttings:

  • Harvest shoots once they grow 3.9” – 5.9” inches tall. 
  • Place them in individual pots, under light shade inside a greenhouse or in a cold frame. 
  • Once they start rooting, plant them in their permanent spot.

During the spring or fall season, divide the plant in large clumps and plant them directly in their permanent spots. 

The smaller clumps must be planted in pots and grown in cold frames until they start rooting. 

Afterward, plant them in their permanent place.

Cluster Bellflower Pest or 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.

Campanula Glomerata Uses

The garden uses of this plant are mostly in rock gardens, beds and borders, cottage garden schemes, wildflower meadow, and informal gardens. 

They look particularly beautiful growing under shrub roses and look great in containers as well.

It goes well with yellow or gold flowering plants for contrast. 

This plant quickly spreads but is managed easily through division during the fall or spring seasons. 

The Campanula plant is deer resistant and also attracts hummingbirds, bees, and other pollinators.