Flower-of-an-hour

Flower-of-an-hour: how do you recognise it?

Habit

Annual, a loose, branching plant about 50 cm high and 40 cm wide.

Leaves

Deeply three-lobed, roughly hairy, fresh green.

Flower

Cream-white to pale yellow with a dark purple centre, 3–5 cm across; each flower stays open only a few hours.

Fruit

The calyx swells into a papery, veined, rounded little lantern containing black seeds.

Roots

Fine and branching; seedlings do not take well to transplanting.

Flowering: July–September · Sowing: March–May · Plants: May–June

Why grow it?

• Flowers from July to September with a constant succession of new blooms, even though each lasts only a few hours.
• Striking flower: cream to pale yellow with a dark purple centre, lovely in sunshine.
• The inflated, papery seed capsules are decorative in their own right.
• Bees visit the flowers readily.
• Easy to grow from seed and content with ordinary, free-draining soil.

Flower-of-an-hour: where does it grow best?

• Full sun and a warm, sheltered spot; on dull days the flowers stay closed.
• Ordinary, free-draining soil: sandy, loamy or clay, acid to chalky. It flowers well even on poor soil.
• Average moisture: water in dry spells, but do not let the soil become waterlogged.
• Space plants 30–40 cm apart; also suitable for large containers.

Light

Sun

Soil type

Sand, loam or clay

Acidity

Not fussy

Moisture

Normal

Size

0.5 m tall, 0.4 m wide

Hardiness

Frost tender: plant out after the last frost (mid-May)

Goes well with

• Cosmos: Airy pink or white flowers in a sunny spot, with the same easy cultivation.
• Cornflower: Blue flowers that contrast beautifully with the cream and purple.
• Marigold: Warm orange and yellow flowers on the same sunny soil.
• Zinnia: Bright summer flowers that enjoy the same warmth and sun.
• California poppy: Orange and yellow flowers for a warm, sunny combination.

Flower-of-an-hour: when and how to plant it?

Plant in May–June.

1. Sow indoors in March–April at 18–22 °C, or straight outdoors in late May, when the soil is warm and night frost is over.
2. The seed has a hard coat: soak it overnight in lukewarm water so that it germinates faster.
3. Sow in individual pots or module trays and disturb the roots as little as possible when transplanting.
4. Plant the young plants out in May–June, 30–40 cm apart, after hardening them off.
5. Water well after planting and keep the soil lightly moist.
6. If you sow outdoors, thin to 30–40 cm between plants.

Care

Water

Regular during growth and in dry spells; never let the soil dry out completely.

Feeding

Little: compost at planting is enough. In containers, a weak dose of flower feed every 3–4 weeks.

Pinching

Pinch out the tip of young plants at 10–15 cm for more branching and more flowers.

Spent flowers

No need to remove them; leave the little lanterns for their decorative value, unless you do not want self-seeding.

Support

Usually not needed; a small stake helps in windy spots.

Tip: Sow indoors in April and plant out after the ice saints; you can also sow again outdoors in May for late flowers. Leave the little lanterns: they look good and give seed for next year.

Flower-of-an-hour: when to prune it?

When: Pruning is not needed. Pinch young plants in June and clear up at the end of the season.

How:

• Pinch out the tip of young plants at 10–15 cm for bushier growth.
• At the end of summer, cut off the seed capsules before they split open if you do not want self-seeding.
• Remove dead or damaged stems.

Pruning calendar and basic rules

Propagation

Seed

Sow indoors in March–April at 18–22 °C or outdoors in late May. Soaking the seed overnight in lukewarm water speeds germination; it takes a few weeks.

Collecting seed

In September, when the lanterns are brown and dry: shake out the black seed, store it dry and cool and sow it the following spring.

Flower-of-an-hour: how does it get through the winter?

Hardy to 0 °C: protect in harsh winters.

• Annual and not hardy: the plant tolerates no frost (0 °C) and dies with the first night frost.
• The seed can overwinter in the soil; in warm gardens the plant often sows itself.
• Clear dead plants in October and, if you like, save seed for next year.

Diseases and pests

• Slugs: Young seedlings are quickly eaten. Protect them with a slug barrier and collect slugs in the evening.
• Aphids and red spider mite: Aphids on young shoots, spider mite in dry weather: fine webs and yellowing leaves. Wash off with water and keep humidity up.
• Damping off: Seedlings collapse at the base because of a fungus. Do not sow too thickly, use clean compost and do not overwater.
• Closed flowers: On cloudy or dark days the flowers do not open. This is normal; they open again in sun.

Through the year

• March: Sow indoors at 18–22 °C.
• April: Sow indoors and pot seedlings on separately.
• May: Late May: sow outdoors or plant out.
• June: Plant out. Pinch young plants.
• July: Flowering begins. Water regularly.
• August: Full flower. Water in dry spells.
• September: Last flowers. Let the capsules ripen or cut them off.
• October: Clear dead plants. Save seed.

Good for wildlife

Bees

Nectar and pollen for honeybees and wild bees.

Did you know?

• The name flower-of-an-hour refers to the short life of each flower, which is often open for only a few hours.
• It belongs to the mallow family, like hollyhock, mallow and cotton.
• The inflated, veined calyx looks like a small paper lantern and stays in place after flowering.