Carolina silverbell

Carolina silverbell: how do you recognise it?

Habit

Small tree or large, often multi-stemmed shrub with a broad, rounded crown, up to about 8 m high and 7 m wide.

Leaves

Oval to elliptic, 5–12 cm, finely toothed; fresh green, yellow in autumn.

Flowers

White, hanging bells of 1–2 cm in clusters of two to five along last year’s shoots, in April–May.

Fruit

Elongated fruit with four wings, green at first and brown in autumn; often stays on the tree for a long time.

Roots

Fine and fairly shallow: it likes a cool, humus-rich soil.

Flowering: April–May · Plants: March–April and October–December · Pruning: June

Why grow it?

• In April–May the branches are hung with white bells: an unforgettable spring picture.
• The flowers are welcomed by bees and bumblebees.
• At around 8 m it stays a modest size.
• Yellow autumn colour and eye-catching winged fruits.
• Fully hardy and rarely troubled by disease.
• Goes beautifully with rhododendrons and other plants for acid soil.

Carolina silverbell: where does it grow best?

• Sun to partial shade; with some afternoon shade the leaves stay in better condition.
• Humus-rich, moist, free-draining sandy or loamy soil, acid to neutral. On chalky soil the leaves turn yellow.
• Sheltered from strong winds and late frosts, for example at the edge of a group of trees.
• Allow a spread of about 7 m. Plant it where you can look up under the branches, so the hanging bells are easy to see.

Light

Sun and partial shade

Soil type

Sand or loam

Acidity

Acid or neutral

Moisture

Normal

Size

8 m tall, 7 m wide

Hardiness

Hardy (to -30 °C)

Goes well with

• Rhododendron: Likes the same acid, humus-rich soil and flowers at the same time.
• Bluebell: A blue carpet beneath the white bells.
• Ferns: Fresh underplanting in partial shade.
• Japanese maple: Fine leaves and autumn colour in the same sheltered spot.

Carolina silverbell: when and how to plant it?

Plant in March–April and October–December.

1. Plant from October to December or in March–April, when the soil is neither frozen nor waterlogged.
2. Dig a hole twice as wide as the root ball and mix in leaf mould or ericaceous compost.
3. Set the plant at the same depth as in the pot and firm the soil.
4. Give a young single-stemmed tree a short stake.
5. Water in well, even if it is raining.
6. Spread a mulch of leaf mould or fine bark around the base.

Care

Water

Weekly in dry weather for the first two years. Later too during long dry spells.

Feeding

A layer of leaf mould in spring; if needed a little feed for acid-loving plants.

Mulching

A yearly layer of leaf mould or fine bark keeps the soil cool, moist and slightly acid.

Around the base

Do not hoe deeply: the fine roots are just below the surface.

Tip: Plant it where you can look up into the crown, for example at the top of a slope or beside a path: the hanging bells are best seen from below. Give it a sheltered spot in humus-rich, acid to neutral soil.

Carolina silverbell: when to prune it?

Pruning months: June.

When: Little needed. If you must, prune straight after flowering, in June.

How:

• Remove dead, damaged and crossing branches.
• On a young tree, decide whether you want a single trunk or a multi-stemmed shrub, and remove whatever does not fit that shape.
• Remove the lowest branches gradually if you want to walk underneath.
• Always cut back to a side branch, never halfway along a branch.

Caution: Do not prune in winter or early spring: the flowers are borne on last year’s wood.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Softwood cuttings

In June: 10 cm cuttings from young shoots, in moist cutting compost under plastic. Rooting powder helps.

Seed

Sow the winged fruits in autumn in a pot left outdoors. The seed is slow to germinate, often only after two winters.

Layering

In spring, bend a low branch down to the ground, lightly wound the bark and pin it down. After a year you can sever it.

Carolina silverbell: how does it get through the winter?

Hardy to −30 °C.

• Fully hardy, to about −30 °C: no protection is needed in Belgium.
• A late frost in April can damage the flowers; a sheltered spot helps.
• A layer of leaf mould around the base protects the shallow roots of young plants.

Diseases and pests

• Yellow leaves: Yellow leaves with green veins: the soil is too chalky. Mulch with leaf mould or pine needles and water with rainwater.
• Frosted flowers: Brown, shrivelled bells after a frosty night in April. Nothing can be done; a sheltered spot prevents a lot of it.
• Leaf scorch: Brown leaf edges in hot, dry summers. Water and mulch, and ideally plant it where it gets some afternoon shade.
• Wind damage: Broken branches in an exposed spot. Cut them cleanly back to a side branch and choose a sheltered spot in future.

Through the year

• March: Planting. Apply leaf mould.
• April: Flowering starts with white bells. Bees. Watch out for night frost.
• May: Flowering. The leaves unfold.
• June: Prune after flowering if needed. Take softwood cuttings.
• July: Water in dry spells. The winged fruits develop.
• August: Water in dry spells.
• October: Yellow autumn colour. Sow seed outdoors. Planting.
• November: Planting. Apply mulch.
• December: Plant in mild weather. Rest.

Good for wildlife

Bees

Nectar and pollen for honeybees and wild bees.

Did you know?

• The genus is named after Stephen Hales, an 18th-century English clergyman and scientist who studied how plants take up and give off water.
• The fruit has four wings, which is why the species is also called Halesia tetraptera, meaning ‘four-winged’.
• It is related to the Japanese snowbell, which also bears hanging white bells.