Venus’s looking-glass

Legousia speculum-veneris

In other languages: Groot spiegelklokje (Nederlands) · Miroir de Vénus (Français)

Venus’s looking-glass is a slender annual cornfield plant from southern and central Europe, also native to Belgium but made rare by intensive farming. It grows 15–30 cm tall and from June to August carries violet-blue, five-lobed star flowers that open in sunny weather. In the garden it is a lovely addition to cornfield annual mixes, chalky lean soil and wildflower meadows. In a suitable spot it seeds itself every year.

Updated on 9 October 2026

Light
Full sun
warm and bright
Moisture
Dry to normal
no wet feet
Legal basis
Sand, loam or clay
neutral to chalky
Hardiness
down to -10 °C
protect in harsh winters
Size
0.3 m
tall, 0.15 m wide
Flowering
June–August

Key facts
Height	0.3 m
Native to Belgium	Yes
Good for bees, butterflies and birds	Yes, for bees
Poisonous to people and pets	Not known to be poisonous
Flowering	June–August

Identify

Venus’s looking-glass: how do you recognise it?

Habit: Slender, branched annual 15–30 cm tall and 10–15 cm wide.
Leaves: Alternate, oblong to spoon-shaped, with a wavy edge, light green.
Flowers: Five-lobed, violet-blue star flowers 1–2 cm across at the tips of the stems, from June to August. They open in sun and close in dull weather.
Fruit: A long, narrow, upright capsule holding many fine seeds.
Roots: Thin and shallow: only moderately drought-tolerant and hard to transplant.

Flowering: June–August · Sowing: March–April and September

In your garden

Why grow it?

Violet-blue star flowers from June to August, a rare colour in a cornfield mix.
A native arable flower that has become rare in the wild: growing it helps it survive.
Bees and other insects visit the flowers.
Grows in lean, chalky soil where few other plants flower so nicely.
Seeds itself year after year in a suitable spot, without any work.

Venus’s looking-glass: where does it grow best?

Full sun.
Lean, chalky soil: sand, loam or clay, neutral to chalky. Do not feed.
Dry to normally moist; not in cold, wet clay.
Choose an open spot with little competition from grass and tall weeds.
Sow in patches or as a mix; the plants are small and look best in drifts.

Light: Sun
Soil type: Sand, loam or clay
Acidity: Neutral or chalky
Moisture: Dry or normal
Size: 0.3 m tall, 0.15 m wide
Hardiness: Tolerates light frost (to -10 °C)

Goes well with

Cornflower: Blue flowers that together with Venus’s looking-glass make a natural blue effect.
Poppy: Red accents in a cornfield mix.
Ox-eye daisy: White flowers that make the violet-blue shades stand out.
Chamomile: A light, white addition in a field or meadow mix.

Maintenance

Venus’s looking-glass: when and how to plant it?

Sow in September or March–April in place; the plant dislikes transplanting.
Make the soil lean and weed-free: remove grass or create bare patches.
Mix the dust-fine seed with sand and scatter it thinly; press it in and barely cover it.
Keep the soil moist until the seeds germinate, after about 2–3 weeks.
Thin only if it is too dense; 10–15 cm between plants is enough.
An autumn sowing gives small rosettes that overwinter and flower earlier in spring.

Care

Water: Only when sowing and in long droughts. After that the plant copes.
Feeding: Do not: rich soil gives tall, floppy plants and more weeds.
Weeding: Keep the seedlings free of weeds for the first weeks; they compete poorly.
Letting it seed: Leave the spent plants until the capsules are ripe; this is how the plant seeds itself.
Clearing: Mow or pull out the plants in autumn after seeding and leave the soil open for next spring.

Tip: Sow the fine seed thinly and never on soil that is already full of grass: this little bellflower loses the fight for light. A bare, lean, chalky spot is ideal.

Venus’s looking-glass: when to prune it?

When: Pruning is not needed: it is an annual.

How:

Leave the spent plants until the capsules are ripe and brown (August–September).
Then mow or pull them out and scatter the seed if you want to spread it.
You can cut a few flower stems for a small bouquet; the plant keeps flowering.

Pruning calendar and basic rules

Propagation

Sowing: Sow in place in September or March–April (see planting). Store the seed dry and cool.
Self-seeding: Let the capsules ripen: the plant seeds itself on open, lean soil.

Venus’s looking-glass: how does it get through the winter?

Hardy to −10 °C: protect in harsh winters.

Annual: the plant dies in autumn. Seedlings from an autumn sowing are hardy to about −10 °C.
No protection needed; leave the soil open so seed can germinate.
Leave the capsules standing until the leaves are dead.

Diseases and pests

Slugs: May strip young seedlings. Collect them in the evening or spread a ring of coarse material.
Competition: Grass and tall weeds smother the small seedlings. Create bare patches and weed in the first weeks.
Tall, floppy plants: On soil that is too rich. Choose a leaner spot and do not feed.
Rotting off: In wet clay seedlings disappear. Choose a well-drained soil.

Through the year

March: Sow in place. Make the soil lean and weed-free.
April: Sow. Weed the seedlings.
May: Weed. Water in a long drought.
June: Flowering begins.
July: Flowers. The bees enjoy them.
August: Last flowers. Let the capsules ripen.
September: Sow for next year. Collect seed.
October: Clear spent plants.

Use

Good for wildlife

Bees: Nectar and pollen for honeybees and wild bees.

You and this species

Did you know?

The Latin name speculum-veneris means ‘mirror of Venus’.
The flowers close in dull weather and in the evening.
Venus’s looking-glass used to be a common cornfield weed, but it has declined sharply with modern farming.

Garden plants · All species