Clustered bellflower

Clustered bellflower: how do you recognise it?

Habit

Clump 40–50 cm tall and about 45 cm wide, with straight, unbranched stems; spreads by rhizomes.

Leaves

Oval to lance-shaped, dark green, rough and hairy; the lower leaves have long stalks, the stem leaves sit directly on the stem.

Flower

Upward-facing, funnel-shaped bells of 2–3 cm in a dense cluster at the top of the stem and in the upper leaf axils, from June to August.

Colour

Violet-blue to deep purple; there are also white and lilac-pink varieties.

Roots

Creeping rhizomes with which it slowly spreads, faster in rich soil.

Flowering: June–August · Sowing: March–April · Plants: March–April and September–October · Pruning: March and July

Why grow it?

• Dense balls of violet-blue bells from June to August, with a repeat flush if you cut it back.
• Native and good for bees, including wild bees that specialise in bellflowers.
• A good cut flower for a summer bouquet.
• Tolerates drought and chalky soil, and is fully hardy.
• Slowly spreads into a colony that leaves little room for weeds.

Clustered bellflower: where does it grow best?

• Sun or light part shade; it flowers most freely in sun.
• Loam or clay, neutral to chalky and well drained.
• Dry to normally moist: it tolerates drought, but not wet feet in winter.
• Plant 35–45 cm apart, in groups of three or more, and give it room to spread.

Light

Sun and partial shade

Soil type

Loam or clay

Acidity

Neutral or chalky

Moisture

Dry or normal

Size

0.5 m tall, 0.45 m wide

Hardiness

Hardy (to -35 °C)

Goes well with

• Rose: A classic pairing: blue bells at the feet of pink or white roses.
• Lady’s mantle: Soft lime green next to violet-blue, also at the front of the border.
• Ox-eye daisy: White daisies beside the blue clusters, in the same sun and soil.
• Wild marjoram: Also native, also likes chalky soil, and a magnet for bees and butterflies.
• Yarrow: Flat yellow or white heads as a contrast in form to the round clusters.

Clustered bellflower: when and how to plant it?

Plant in March–April and September–October.

1. Plant in March–April or September–October.
2. Loosen the soil and mix in some compost; on heavy clay, add a little coarse sand for better drainage.
3. Set the plant at the same depth as it was in its pot and firm the soil.
4. Leave 35–45 cm between plants.
5. Water well straight away, then in dry spells for the first few weeks.
6. A thin layer of compost around the base keeps the soil moist while the plant roots in.

Care

Water

In dry spells after planting; once established it copes well with a dry period.

Feeding

A spadeful of compost in March. Too much feed gives floppy stems.

Deadheading

In July, cut flowered stems back to the leaves at the base for a repeat flush.

Cut flowers

Cut the stems when the first bells in the cluster have opened.

Runners

If the colony gets too big, slice off the outer parts with a spade in spring.

Tip: In July, cut the faded stems back to the leaves and give water and compost: you will get a second, smaller flush in late summer. If the colony gets too big, slice off the edge in spring.

Clustered bellflower: when to prune it?

Pruning months: March and July.

When: In July, after the first flush, cut back the faded stems. In March, clear away last year’s dead remains.

How:

• Cut faded flower stems back to just above the leaves at the base.
• Then water and add some compost: a smaller repeat flush often follows in late summer.
• In between, cut off faded clusters if you do not want seedlings.
• In March, cut last year’s dead stems and leaves down to the ground.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Division

In March–April or September: lift a clump or slice off a piece from the edge, with rhizomes and shoots, and replant it elsewhere straight away. Water.

Seed

Indoors in March–April: scatter the fine seed on moist seed compost and press it in lightly without covering it. Keep it in a light spot at 15–20 °C; it germinates in 2–4 weeks. Plant out in May; it usually flowers from the second year.

Clustered bellflower: how does it get through the winter?

Hardy to −35 °C.

• Fully hardy, to about −35 °C: no protection needed.
• The top growth largely dies down; in spring it shoots again from the rhizomes.
• Wet soil in winter is more dangerous than frost: make sure drainage is good, especially in a pot.

Diseases and pests

• Slugs: Eat the young shoots in spring. Pick them off in the evening, especially in damp weather.
• Spreading: In rich, moist soil it spreads quickly. Slice off runners at the edge with a spade in spring.
• Rust: Orange pustules on the undersides of the leaves. Cut off affected leaves and do not put them on the compost heap.
• Powdery mildew: White powder on the leaves, especially after flowering in dry summers. Cutting back after flowering helps: the new foliage is healthy.

Through the year

• March: Clear old stems. Plant or divide. Sow indoors. Add compost.
• April: Plant. Sow indoors. Watch out for slugs.
• May: Plant out seedlings. Water in dry weather.
• June: Flowering starts. Cut flowers.
• July: Cut back after the first flush. Water and add compost.
• August: Repeat flowering. Water in dry weather.
• September: Plant or divide.
• October: Plant. The foliage starts to die down.

Good for wildlife

Bees

Nectar and pollen for honeybees and wild bees.

Did you know?

• ‘Glomerata’ means ‘gathered into a ball’: the flowers are packed together like a little ball of wool. The Dutch name, kluwenklokje, says the same.
• Some wild bees, such as scissor bees, collect pollen only from bellflowers.
• In bellflowers the anthers open while the flower is still in bud: the pollen sticks to hairs on the style, where bees collect it later.