Sieber's crocus

Sieber's crocus: how do you recognise it?

Corm

Small corm 1–2 cm across with a brown, fibrous tunic; plant it in autumn.

Leaves

Narrow and grassy, dark green with a white central stripe; they appear at the same time as the flowers.

Flowers

Goblet-shaped, 3–4 cm long; in sun they open into a star, closing in the evening and in dull weather.

Colour

Lilac to violet-blue with a golden-yellow throat; there are also white and three-coloured forms.

Height

About 8 cm: a true miniature.

Flowering: February–March · Plants: September–November

Why grow it?

• One of the earliest flowers of the year: colour in February and March.
• An important early source of pollen and nectar for bees and bumblebees.
• Stays very small: ideal for a rock garden, a pot and the front of a border.
• In a good spot it spreads by itself into a small carpet.
• Easy and hardy: plant it once and it comes back every year.

Sieber's crocus: where does it grow best?

• Full sun: the flowers only open fully in sunshine.
• Sandy or loamy, well-drained soil, neutral to chalky.
• Dry to moist; in summer, when the corm is dormant, rather dry than wet.
• Rock garden, gravel garden, front of a border, under deciduous shrubs or in a pot. In a lawn too, as long as you only mow once the leaves have turned yellow.

Light

Sun

Soil type

Sand or loam

Acidity

Neutral or chalky

Moisture

Dry or normal

Size

0.08 m tall, 0.05 m wide

Hardiness

Hardy (to -20 °C)

Goes well with

• Snowdrop: Flowers at the same time and fills the partly shaded spots.
• Winter aconite: Yellow flowers with a green ruff in February: a cheerful contrast with the lilac.
• Dwarf iris: Blue and purple flowers at the same time, for the same sunny rock garden.
• Glory-of-the-snow: Blue stars that flower just after the crocus.
• Thyme: A low, evergreen mat for the crocuses to push through.

Sieber's crocus: when and how to plant it?

Plant in September–November.

1. Plant the corms in September–November.
2. Plant 5–8 cm deep, pointed end up.
3. Space them 5–8 cm apart, in groups of at least ten for a good effect.
4. On heavy soil, work some coarse sand into the planting spot.
5. In a pot you can plant them closer together, in potting compost with some sand and a drainage hole.
6. Water after planting if the autumn is dry.

Care

Watering

Usually not needed in the garden. Keep pots slightly moist while growing and dry in summer.

Feeding

Not needed; on poor soil add a little compost after flowering.

Leaves

Leave the foliage for about six weeks after flowering until it turns yellow: this lets the corm build up reserves for next year.

Faded flowers

No need to remove them: they wither discreetly. Leave them if you want it to self-seed.

Pots

After flowering leave the pot outdoors until the leaves die back, then store it dry until autumn, or plant the corms out in the garden.

Tip: Plant it in the sunniest spot you have, ideally where you can see it from the house: the flowers only open fully in sunshine. Plant in groups of at least ten.

Sieber's crocus: when to prune it?

When: No pruning is needed. After flowering simply let the leaves die back.

How:

• Leave the faded flowers; they disappear on their own and sometimes set seed.
• Only cut or mow the leaves once they are completely yellow, usually in May.
• In a rock garden, remove the dead leaves to keep the spot tidy.

Caution: Do not mow a lawn with crocuses too early: without leaves the corm cannot build up enough reserves.

Pruning calendar and basic rules

Propagation

Cormlets

Small corms form around the main corm. Lift dense clumps in summer, once the leaves have gone, and replant them in autumn.

Seed

In a good spot it self-seeds. Seedlings flower after two to three years.

Sieber's crocus: how does it get through the winter?

Hardy to −20 °C.

• Hardy to about −20 °C: no protection is needed in Belgium.
• The flowers tolerate frost and snow; after a cold night they simply open again in the sun.
• Keep pots outdoors in a sheltered spot: the corms need winter cold to flower.

Diseases and pests

• Mice and squirrels: They dig up and eat the corms. After planting, lay a piece of wire mesh over the spot or plant in a mesh basket.
• Sparrows: They shred the flowers, especially early in spring. A few twigs or a string stretched above the flowers keeps them away.
• Flowers do not open: Not enough sun. Move the corms to a sunny spot.
• Corm rot: Corms rot in wet soil. Make sure the soil drains well.

Through the year

• February: Flowering starts. The first bees on the flowers.
• March: Flowering. Leave the faded flowers.
• April: Let the leaves die back. Keep pots slightly moist.
• May: The leaves turn yellow; only now cut or mow them.
• June: Dormancy. Lift and divide dense clumps.
• September: Plant corms 5–8 cm deep.
• October: Plant corms. Wire mesh against mice.
• November: Plant the last corms. Put pots outdoors.

Edible and useful

Not edible. Crocuses are mildly poisonous: eating a corm or leaves can cause stomach upsets, with vomiting and diarrhoea, and dogs and cats fall ill from them too. Dogs sometimes dig up newly planted corms: plant them where your dog does not dig, and keep loose corms in a labelled bag out of reach of children and pets. The yellow or orange stigmas in the flower are not saffron: that comes only from the saffron crocus (Crocus sativus), which flowers in autumn. Do not confuse crocuses with Colchicum either, which is sometimes called autumn crocus or meadow saffron but is not a crocus and is highly poisonous: a crocus has three stamens, Colchicum six. If you also buy or store Colchicum corms, keep them separate and labelled. 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?

• It is named after Franz Wilhelm Sieber, a plant collector from Prague who collected plants on Crete in the early 19th century.
• The flowers open in sun and warmth and close again in the evening or in dull weather.
• Saffron does not come from this crocus but from the autumn-flowering saffron crocus (Crocus sativus).