Summer hyacinth

Summer hyacinth: how do you recognise it?

Habit

Bulb about 1 m tall and 20 cm wide, with straight, sturdy stems.

Leaves

Broad, strap-like and grey-green, in a clump at the base; the flower stem itself carries no leaves.

Flower

Long raceme of nodding white bells that open from the bottom up, from July to September.

Fruit

After flowering, green seed capsules on the stem.

Bulb

Large, round bulb that is planted deeply; offsets form.

Flowering: July–September · Plants: March–April

Why grow it?

• Flowers from July to September with white bells, when many borders are losing colour.
• A graceful vertical accent about 1 m tall among lower perennials.
• Bees visit the flowers for nectar and pollen.
• The white flowers glow at dusk and suit a white or silver planting scheme.
• Returns for years after planting and slowly multiplies by offsets.

Summer hyacinth: where does it grow best?

• Full sun; in partial shade the stem gets longer and flowers less.
• Deep, humus-rich, free-draining soil: sand, loam or clay, neutral to chalky.
• Moderately moist during the growing season; in winter the soil should drain well.
• Sheltered from strong wind, because the tall stems can topple.
• Plant in groups of 3–7 bulbs, 25–30 cm apart.

Light

Sun

Soil type

Sand, loam or clay

Acidity

Neutral or chalky

Moisture

Normal

Size

1 m tall, 0.2 m wide

Hardiness

Hardy (to -15 °C)

Goes well with

• Coneflower: Purple flowers and brown cones beside the white bells, at the same time.
• Garden phlox: Pink and white plumes that flower at the same time.
• Dahlia: Warm colours that make the white racemes stand out.
• Ornamental grasses: Airy plumes that frame the tall stems.

Summer hyacinth: when and how to plant it?

Plant in March–April.

1. Plant in March–April, once the worst frosts are over.
2. Dig a hole 15 cm deep; improve heavy clay with coarse sand and compost.
3. Set the bulb pointed end up with the top about 15 cm below the soil surface.
4. Leave 25–30 cm between bulbs and plant in groups of 3–7 among perennials.
5. Water once after planting; after that only if it stays dry for a long time.
6. Mark the spot, because the shoots appear fairly late in spring.

Care

Water

During the growing season, water generously once a week in dry weather, especially while the stems are growing and flowering.

Feeding

Compost or organic fertiliser in spring. Too much nitrogen gives long, floppy stems.

Support

In windy spots, support the stems with a stake or let neighbouring perennials do the job.

Spent flowers

Cut off the spent stem unless you want to leave the seed capsules as decoration.

Mulching

In late autumn, spread a thick layer of leaf mould or mulch over the bulbs, especially in cold, wet spots.

Tip: Often sold as Galtonia candicans. Plant the large bulbs in March–April, 15 cm deep, in small groups among perennials, which support the tall stems and hide the leaf bases.

Summer hyacinth: when to prune it?

When: No pruning is needed. Cut off spent stems in September–October and yellow leaves in autumn.

How:

• Cut the spent stem off at the base, or leave it for the decorative seed capsules.
• Leave the leaves until they turn yellow, then remove them.
• In spring, cut away any yellow foliage that remains.

Caution: Do not cut off the green leaves, because the bulb needs them to build up reserves for next year.

Pruning calendar and basic rules

Propagation

Offsets

In March–April: lift the bulbs, separate the small offsets and replant them straight away, 10–15 cm deep. They flower after a few years.

Seed

Sow in spring in pots of seed compost in a bright, cool place; seedlings take several years to flower.

Summer hyacinth: how does it get through the winter?

Hardy to −15 °C: protect young plants.

• Hardy to about −15 °C: in free-draining soil the bulb is safe without protection.
• In cold or wet spots, cover the bulbs with 10 cm of leaf mould or mulch in November.
• On heavy, wet clay you can lift the bulbs once the leaves have died back, store them dry and frost-free in peat or sand, and replant in March.
• In a pot: put it in a sheltered spot, not too wet, and protect it from hard frost.

Diseases and pests

• Slugs: They eat young shoots and leaves in spring. Collect them in the evening with a torch or set slug traps.
• Bulb rot: The bulb is soft and mouldy, especially in wet winters. Provide well-drained soil and remove affected bulbs.
• Toppling: The tall stems break or tilt after rain or wind. Choose a sheltered spot, support them or surround them with perennials.
• No flowers: Leaves appear but no flowers. The cause is usually too much shade, planting too sparsely or a young bulb. Move it to a sunny spot and give it time.

Through the year

• March: Plant or move bulbs.
• April: Plant. Watch for slugs.
• May: Shoots appear. Deal with slugs.
• June: Leaf growth; water in dry weather. Put in supports if needed.
• July: Flowering begins.
• August: Full flower.
• September: Flowering ends. Cut off spent stems.
• October: Remove yellow leaves.
• November: Spread mulch over the bulbs.

Edible and useful

Not edible. All parts of star-of-Bethlehem are poisonous, especially the bulbs, which look like little onions; the flowers and the vase water are poisonous too, to people and pets. Never store the bulbs with the vegetables and keep a vase out of reach of children and cats. If any is swallowed, call a poison centre (in Belgium 070 245 245) or your doctor at once.

Good for wildlife

Bees

Nectar and pollen for honeybees and wild bees.

Did you know?

• The former genus name Galtonia honours Francis Galton, a British explorer who travelled in southern Africa in the nineteenth century.
• The bells on the raceme open from the bottom up, so flowering lasts for weeks.
• The species name candicans comes from Latin and means ‘white’ or ‘becoming white’.