Algerian iris

Algerian iris: how do you recognise it?

Habit

Compact clump about 30 cm tall and 60 cm wide, which widens slowly.

Foliage

Narrow, grassy and evergreen, 30–60 cm long, dark green; the leaves flop over a little.

Flower

Lilac to violet-purple flowers 7–8 cm across with yellow streaks in the throat, in winter, from November to March.

Scent

The flowers have a soft, sweet scent.

Roots

A thin, creeping rhizome lying just below the surface.

Flowering: November–March · Plants: April–May and September · Pruning: September–October

Why grow it?

• Flowers from November to March, in the depths of winter, when the garden is nearly all grey.
• Lilac flowers with a yellow throat and a soft, sweet scent.
• Evergreen, grassy foliage that stays fresh all year.
• Loves dry, poor soil and full sun: ideal for a warm wall or a gravel garden.
• Almost maintenance-free and long-lived; the flowers are also lovely in a vase.

Algerian iris: where does it grow best?

• Full sun, preferably in front of a warm, sunny wall: the hotter and drier the summer, the better the flowering.
• Poor, well-drained soil: sand or loam, neutral to chalky. Heavy clay or rich soil gives lots of leaf and few flowers.
• Dry: it tolerates drought extremely well and hates standing water.
• Sheltered from cold wind and above all from cold, damp spots.
• Space plants 40–50 cm apart; it forms a dense clump after a few years.

Light

Sun

Soil type

Sand or loam

Acidity

Neutral or chalky

Moisture

Dry

Size

0.3 m tall, 0.6 m wide

Hardiness

Hardy (to -15 °C)

Goes well with

• Lavender: Scent and colour in a sunny, dry border.
• Stonecrop: A low, drought-tolerant plant for the sunny front.
• Ornamental grasses: Fine stems as a soft backdrop.
• Snowdrops: Flower in the same winter period.
• Sage: Blue-purple spikes that match the lilac flowers.

Algerian iris: when and how to plant it?

Plant in April–May and September.

1. Plant in April–May or in September, when the soil is not wet.
2. Dig a shallow hole and mix in sand, grit or lime for better drainage; compost is not needed.
3. Lay the rhizome shallowly, so the top sits almost at the surface and gets the sun.
4. Leave 40–50 cm between plants.
5. Water once after planting and after that only in prolonged drought.
6. Do not mulch over the rhizome; a thin layer of grit at the base is fine.

Care

Water

Almost never: only in the first year in prolonged drought. Too much water causes rot and foliage without flowers.

Feeding

Do not feed: poor soil gives more flowers than rich soil.

Old foliage

In September–October, cut the old foliage back to about 10–15 cm so the flowers show in winter.

Slugs

Check for slugs in winter; they eat the buds; see problems.

Leave undisturbed

Do not move it: after being moved it sometimes does not flower for 1–2 years.

Tip: Put it against a warm south wall on poor, dry soil and cut the old foliage back in autumn so the flowers show. Never feed it.

Algerian iris: when to prune it?

Pruning months: September–October.

When: In September or October, cut the old foliage back so the flower buds are free.

How:

• Cut the old, tatty foliage back to about 10–15 cm above the ground.
• Remove dead or brown leaves and spent flowers.
• Cut buds in winter if you want them in a vase; they open indoors.

Caution: All parts are poisonous, especially the rhizome. Wear gloves: the sap can irritate the skin.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Division

After flowering in April–May or in September, lift the clump and split it with a sharp knife into pieces with a leaf fan and rhizome. Replant shallowly. Do this only if the clump gets too dense, as it sometimes does not flower for 1–2 years afterwards.

Seed

Sow seed in autumn; it germinates slowly and unevenly. Plants flower only after 3 years or longer.

Algerian iris: how does it get through the winter?

Hardy to −15 °C: protect young plants.

• Hardy to about −15 °C: most Belgian winters pass without protection, especially against a warm wall.
• In hard frost, open flowers can be damaged; the buds usually survive. Cover with horticultural fleece in frost.
• In a pot: put it under cover, in a cold, bright greenhouse or porch, so the flowers are protected from rain and slugs.

Diseases and pests

• Slugs: Slugs eat the buds and flowers in winter. Pick off slugs, lay a barrier of crushed shells or set a slug trap.
• No flowers: Usually too much feed or water, too much shade or a cool summer. Do not feed, plant in sun and keep dry.
• Rhizome rot: The foliage turns yellow and the rhizome smells after a wet spell. Ensure good drainage.
• Frost damage: Open flowers turn brown in hard frost. Cover with horticultural fleece or cut the buds and put them in a vase indoors.

Through the year

• January: Flowering. Watch for slugs.
• February: Flowering. Bring buds indoors in a vase.
• March: Flowering ends. Remove spent flowers.
• April: Plant or divide after flowering.
• May: Plant or divide. The sun ripens the rhizome.
• June: Do nothing. Do not water.
• July: Leave dry and warm: this encourages flowering.
• August: Leave dry and warm.
• September: Plant or divide. Cut back old foliage.
• October: Cut old foliage back to 10–15 cm.
• November: Flowering begins. Control slugs.
• December: Flowering. Bring buds indoors in a vase.

Edible and useful

Not edible. All parts of these irises are poisonous, especially the rhizome: eating any causes vomiting, stomach ache and diarrhoea, and dogs, cats and grazing livestock fall ill from it too. The main risk comes when you divide the clumps: clear up the loose pieces of rhizome straight away, do not leave them lying where children play or dogs dig, and do not throw them into a field or run. Siberian and Japanese iris like the edge of a pond, where without flowers their leaves look like those of other waterside plants: do not eat anything from a waterside plant you are not sure of. The sap can irritate the skin: wear gloves when dividing and cutting back. If any is swallowed, call a poison centre (in Belgium 070 245 245) or your doctor at once.

Did you know?

• The species name unguicularis refers to the claw-like base of the petals (Latin: unguis, nail).
• An older botanical name is Iris stylosa.
• The flowers often emerge so low from the leaf fan that they seem almost stemless; what you see is the long tube of the flower.