Alocasia nebula 'Silver' ('Black Diamond')

Background of Alocasia nebula ‘Silver’ (‘Black Diamond’)

‘Silver’ (‘Black Diamond’) belongs to Alocasia nebula, a species known from Sarawak on Borneo. Alocasia nebula may grow in lowland limestone forest near Semenggoh. Its exact habitat is unknown.

Care for Alocasia nebula ‘Silver’ (‘Black Diamond’)

• Light: Keep the leaves in shade to softly filtered light. Strong sun can bleach or scorch them.
• Watering: During active growth, let the upper part of the mix dry a little, then water while some moisture remains deeper around the roots. Water until excess runs from the drainage holes. Let the pot drain, then empty any water left in the saucer or cover pot.
• Potting mix: Use a coarse, rich mix that stays moist without becoming dense or waterlogged. If you include dolomite, use only a small amount of coarse crushed dolomite and avoid fine powder.
• Temperature: Keep it around 21–29 °C and away from cold windows or draughts. Move it away from cooler spots before temperatures fall below 15 °C.
• Humidity: Keep the air humid, especially while a new leaf is opening.
• Propagation: Mature plants can produce small corms on thin runners. Some can stay dormant for a long time, so keep a firm corm even if it has not sprouted yet.

Alocasia nebula 'Silver' ('Black Diamond'): common problems

• The leaves go limp and the plant starts collapsing when the root zone is cold and wet: Move it back to steady warmth and leave the watering can alone until the potting mix is no longer soaking wet. If the plant keeps declining, check the roots and base. Keep anything firm and cut away only tissue that is unmistakably rotten.
• The plant stops making new growth even though healthy roots have crowded the pot: If firm roots are packed throughout the mix with very little room left, move the plant into a slightly larger container with an airy mix. Do not increase fertiliser simply because growth has paused.
• Fresh leaves open with rough pale scars or tiny black specks: Inspect the youngest folded growth for thrips and dark droppings. If you find them, isolate the plant before treating it. Use a treatment labelled for thrips on indoor ornamental plants, and repeat it only as directed on the label.

Alocasia nebula ‘Silver’ (‘Black Diamond’): toxic if chewed

• Pets: This Alocasia is toxic to cats and dogs. Keep the plant and any cut pieces where pets cannot chew them.
• Children and handling: Keep it out of reach of children. Sap from damaged tissue can irritate skin and eyes, so wash your hands after pruning and avoid touching your face.
• Why it irritates: Alocasia tissue contains insoluble calcium oxalate crystals. Chewing or contact with sensitive tissue can cause immediate local irritation.
• Possible symptoms: Mouth exposure can cause burning pain, drooling, swelling, nausea or vomiting, and difficulty swallowing.
• After exposure: For a pet, contact a veterinarian. For a person, remove any plant material from the mouth and rinse with water; seek medical or poison-control advice if symptoms are significant. Breathing difficulty or rapidly increasing swelling needs urgent medical attention.

What nebula means

The Latin word nebula means “mist” or “cloud” and reflects the softly clouded colouring across the leaves.

Alistair Hay first described Alocasia nebula in 2000 in Curtis’s Botanical Magazine, volume 17, page 16.