Photo: Khalid Mahmood at English Wikipedia, Public domain · source

Annual · Nyctaginaceae

Four o’clock flower

Mirabilis jalapa

In other languages: Nachtschone (Nederlands) · Belle-de-nuit (Français)

The four o’clock flower comes from tropical America and is really a perennial with a thick, dark tuberous root, usually grown here as an annual. It forms a dense, rounded bush of about 80 cm with glossy green leaves. From July until the first frost its trumpet-shaped flowers only open late in the afternoon and stay open and fragrant until the next morning, which is where the name comes from. They come in magenta, yellow, white, red and pink, often in several colours or striped on the same plant. Gardeners love it for its sweet evening scent by the patio and because it is so easy to grow.

Caution: All parts are poisonous, especially the seed and the tuberous root: swallowing them makes you ill. Take care with young children, who love picking up the little black seeds, and with dogs and cats. Remove the seed where children play and keep lifted tubers out of their reach.

Updated on 10 October 2026

Light
Full sun
warm and bright
Moisture
Normal
no wet feet
Legal basis
Sand, loam or clay
any pH
Hardiness
down to -5 °C
protect in harsh winters
Size
0.8 m
tall, 0.6 m wide
Flowering
July–October

Key facts
Pruning months	October
Height	0.8 m
Native to Belgium	No, planted
Good for bees, butterflies and birds	Yes, for butterflies
Poisonous to people and pets	Yes, take care with children and pets
Flowering	July–October

Identify

Four o’clock flower: how do you recognise it?

Habit: Rounded and densely branched, like a small shrub, 60–80 cm tall and about 60 cm across.
Leaves: Oval to heart-shaped, pointed, 5–10 cm, glossy fresh green, opposite.
Flower: Trumpet-shaped, with a long tube and an open mouth of about 3 cm, in small clusters at the tips; open from late afternoon until the next morning, from July to October.
Colour: Magenta, pink, red, yellow and white, often striped or flecked, and often several colours on the same plant.
Seed: Black, wrinkled seed the size of a peppercorn; poisonous.
Tuber: A thick, dark tuberous root that grows bigger each year and can overwinter frost-free; poisonous.

Flowering: July–October · Sowing: March–May · Plants: May–June · Pruning: October

In your garden

Why grow it?

A sweet scent in the evening and at night: ideal by a patio or seat.
Flowers tirelessly from July until the first frost.
Different colours, striped and flecked flowers on one plant: a surprise every evening.
Moths are drawn to the fragrant flowers.
Easy from seed, and the tuber can be kept for years, like a dahlia.
Copes with heat and some drought, even in a large pot.

Four o’clock flower: where does it grow best?

Full sun and a warm spot; in shade it flowers far less.
Ordinary, well-drained garden soil: sand, loam or clay, acid to chalky.
Moderately moist; water regularly in a pot.
Allow 50–60 cm per plant, near the patio or a window where you sit in the evening.

Light: Sun
Soil type: Sand, loam or clay
Acidity: Not fussy
Moisture: Normal
Size: 0.8 m tall, 0.6 m wide
Hardiness: Tolerates light frost (to -5 °C)

Goes well with

Flowering tobacco: Another evening-scented plant: together a fragrant patio.
Dahlia: The same sunny border and the same winter storage of the tubers.
Cosmos: Airy flowers by day, while the four o’clock only opens in the evening.
Ornamental grasses: Fine stems between the dense, green bushes.

Maintenance

Four o’clock flower: when and how to plant it?

Plant in May–June.

Sow indoors in March–April, one or two seeds per small pot, 1–2 cm deep, at 18–20 °C; soaking overnight speeds up germination.
Or sow where it is to flower in May, once the soil is warm.
Pot up an overwintered tuber indoors in April in potting compost, so it starts into growth.
Plant out after mid-May, when there is no more risk of night frost, 50–60 cm apart; set a tuber with its top about 5 cm below the surface.
Water in well after planting and spread a little mulch around the base.

Care

Watering: Water regularly in dry spells; more often in pots. Established plants tolerate some drought.
Feeding: A spadeful of compost at planting is enough. In pots, a little flowering-plant feed every three weeks.
Mulching: A layer of compost keeps the soil moist and cool in summer.
Deadheading: Not needed: the plant keeps flowering on its own. Remove the seed if you do not want seedlings or if children play nearby.
Tuber: Lift the tuber in October–November, after the first light frost, and store it frost-free.

Tip: Grow four o’clocks by the patio or under an open bedroom window: the flowers open as you get home and stay fragrant late into the night.

Four o’clock flower: when to prune it?

Pruning months: October.

When: No pruning is needed. In October, after the first light frost, cut the stems off when you lift the tuber.

How:

Cut the frost-blackened stems back to about 10 cm above the ground.
Lift the tuber carefully, let the soil dry and brush it off.
In summer simply cut back broken or over-long stems.

Caution: The tuber and seed are poisonous: wash your hands after handling them and leave nothing lying around where children or pets can reach it.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Seed: Sow indoors in March–April or outdoors in May. Collect the black seeds in September–October and store them dry, out of reach of children.
Keeping the tuber: Lift the tuber in autumn, store it frost-free and replant it the following year: older tubers give bigger plants.

Four o’clock flower: how does it get through the winter?

Hardy to −5 °C: protect in harsh winters.

Not fully hardy: the tuber tolerates a few degrees of frost, to about −5 °C, but in a wet or severe Belgian winter it rots or freezes.
Lift the tuber in October–November, let it dry for a few days and store it frost-free at 5–10 °C in dry sand or newspaper, like a dahlia.
Against a sheltered south-facing wall you can leave it in the ground under a thick mulch, but that does not work every winter.
In a pot: move the pot with the tuber somewhere dry and frost-free, such as a garage or cellar.

Diseases and pests

Aphids: On young shoots. Spray off with water; ladybirds help.
Slugs: They eat young plants. Protect them for the first weeks and pick slugs off in the evening.
Tuber rot: Soft, rotting tubers in storage. Let them dry well before storing and keep them cool, dry and frost-free.
Few flowers: Too much shade or too much nitrogen. Choose a sunny spot and feed less.

Through the year

January: Check stored tubers for rot.
March: Sow indoors at 18–20 °C.
April: Sow indoors. Pot up overwintered tubers indoors.
May: Plant out after mid-May or sow in place.
June: Plant. Water in dry spells.
July: Flowering starts; enjoy the scent in the evening.
August: Full flower. Water in dry spells.
September: Flowering. Collect seed.
October: Last flowers. After the first frost cut the stems off and lift the tubers.
November: Dry the tubers and store them frost-free.

Use

Edible and useful

Not edible. All parts of four o’clock plant are poisonous, especially the seeds and the tuberous root: swallowing any causes vomiting, stomach ache and diarrhoea, and the sap can irritate the skin. The black, wrinkled seeds easily fall to the ground and children like to pick them up: remove them where children play and keep seed out of their reach. If you lift the tubers in autumn to overwinter indoors, store them dry and out of reach of children and pets, and not with the potatoes or other vegetables. If any is swallowed, call a poison centre (in Belgium 070 245 245) or your doctor at once.

Good for wildlife

Butterflies: Nectar for butterflies.

You and this species

Did you know?

One plant can carry flowers in different colours, as well as striped and flecked flowers.
In the early 20th century the German botanist Carl Correns studied heredity with the four o’clock flower: a red and a white parent give pink offspring.
Mirabilis means ‘wonderful’ in Latin.

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