Stromanthe

Stromanthe: how do you recognise it?

Habit

Clump-forming plant 60–80 cm tall and up to 60 cm wide, with upright leaf stalks rising from a rhizome.

Leaves

Lance-shaped to oblong, 20–40 cm, leathery; dark green above with a cream and pink pattern, purple-red underneath.

Flowers

Rarely flowers indoors. The small white flowers sit in red bracts at the top of the stem.

Movement

The leaves fold upwards in the evening (night position) and unfold again in the morning.

Roots

Shallow rhizome with tuberous roots: a wide, not too deep pot suits it best.

Plants: April–May

Why grow it?

• Striking variegated foliage in green, cream and pink, with a purple-red underside.
• It moves: the leaves fold upwards in the evening and open again in the morning.
• A shade plant for indoors that stays beautiful even without sun.
• Gives a tropical feel to a room and goes well with other foliage plants.
• At 60–80 cm tall it is a compact plant for a table or sideboard.

Stromanthe: where does it grow best?

• Bright to half shade without direct sun: strong sun bleaches the pattern and scorches the leaves.
• Warm and even, 18–25 °C and never below 15 °C; no draughts and no cold windowsill.
• Light, humus-rich, airy potting compost with a little perlite; slightly acid to neutral.
• Evenly moist, never wet and never bone dry; humidity of at least 50–60 %.
• In winter do not put it right next to a radiator or near an open window.

Light

Bright, out of direct sun

Potting soil

Multi-purpose compost or airy, humus-rich compost

Acidity

Acid or neutral

Watering

Moderately or generously

Size

0.8 m tall, 0.6 m wide

Temperature

Minimum 15 °C

Goes well with

• Calathea: A relative with the same warmth and humid air needs but a very different leaf pattern.
• Maranta: Also a prayer plant; the foliage folds up in the evening, as with stromanthe.
• Fern: Loves the same humid air and gives a soft, green contrast.
• Fittonia: Low plant with fine veins for the foot of the group, with the same care.

Stromanthe: when and how to plant it?

Plant in April–May.

1. Repot in April–May, when the plant has outgrown its pot or the compost is exhausted; about every 1–2 years.
2. Choose a pot 2–4 cm wider than the old one, wide rather than deep, with a drainage hole.
3. Put clay pebbles at the bottom and fill with light potting compost mixed with a quarter perlite.
4. Set the plant at the same depth as before and firm lightly.
5. Water with lukewarm, low-lime water until it runs out of the hole and let the surplus drain away.
6. Put it in a bright place without sun and wait 4–6 weeks before feeding again.

Care

Water

Lukewarm, low-lime water (rainwater or filtered water). Keep the compost evenly moist and water as soon as the top centimetre is dry. Hard water causes brown leaf edges.

Humidity

In dry air the leaves curl and the edges turn brown. Stand it on a tray of clay pebbles and water, group plants together or use a humidifier.

Feeding

From April to September a houseplant feed at half strength every 2–4 weeks; none in winter.

Leaves

Wipe the leaves now and then with a damp cloth and remove dead leaves at the base.

Turning

Turn the pot a quarter turn regularly so it grows evenly.

Tip: If the leaves fold upwards in the evening, that is normal. If they stay rolled up during the day, it is thirsty or the air is too dry.

Stromanthe: when to prune it?

When: Real pruning is not needed. Cut off dead or damaged leaves as soon as you see them, preferably in spring.

How:

• Cut dead or brown leaves off at the base with clean scissors.
• Brown leaf edges can be trimmed following the natural leaf shape; leave a narrow rim.
• Remove old, bare stems at the base so new shoots have room.

Pruning calendar and basic rules

Propagation

Division

April–May, when repotting: take the plant out of the pot, divide the rhizome with a sharp knife into pieces with at least 2–3 leaves and roots each, and pot them up separately in moist compost. Keep them warm, humid and sheltered until they grow on.

Stromanthe: how does it get through the winter?

• Not hardy: the minimum is 15 °C. Below that it loses leaves or starts to decline.
• Keep it warm (18–22 °C) and bright, without draughts and not against a cold window.
• Water less, but never let the compost dry out; do not feed.
• Central-heating air is very dry: put a tray of clay pebbles and water or a humidifier nearby.

Diseases and pests

• Brown leaf edges: Dry air or hard water. Give more humidity and use soft water; trim the brown edges.
• Curling leaves: A sign of drought or low humidity. Water and put it somewhere more humid.
• Faded pattern: Too much sun, or on the contrary too little light. Move it to a bright place without sun.
• Spider mites: Fine webbing under the leaves and pale speckles in dry, warm air. Shower with lukewarm water and raise the humidity.
• Root rot: Yellow, limp leaves and wet, smelly compost after too much water. Let it dry out, or repot in fresh, light compost and remove rotten roots.

Through the year

• January: Warm and bright. Little water, no feeding.
• February: Keep an eye on the humidity.
• March: Give more light and water as it grows.
• April: Repot or divide. Start feeding.
• May: Repot if needed. Feed.
• June: Soft water, humid air. Feed.
• July: Shade from strong sun. Feed.
• August: Feed. Check for spider mites.
• September: Last feed.
• October: Less water. Keep warm.
• November: Dry heating air: raise the humidity.
• December: Rest. Warm and bright, little water.

Did you know?

• Stromanthe, calathea and maranta belong to the same family, the Marantaceae. They are known as ‘prayer plants’ because their leaves fold upwards in the evening.
• The movement comes from a small cushion (pulvinus) at the base of the leaf, which tilts the leaf as the water pressure changes.
• Stromanthe thalia was long called Stromanthe sanguinea: you will find both names in shops.