Alocasia macrorrhizos ‘New Guinea Gold’

Local form and natural range of Alocasia macrorrhizos ‘New Guinea Gold’

‘New Guinea Gold’ is a local form of Alocasia macrorrhizos from New Guinea. The wider species grows across the rainy tropics of the Malay Archipelago and western Pacific.

Growing Alocasia macrorrhizos ‘New Guinea Gold’

• Growth and space: For ‘New Guinea Gold’, this can become a tall trunk-forming plant, reaching about 250 cm with a spread around 200 cm. Use a stable container and leave headroom as the stem develops.
• Watering: During active growth, check the upper layer as well as deeper in the pot. Water when the upper layer feels dry while some moisture remains deeper around the roots. Give a thorough watering and allow all surplus water to leave through the drainage holes.
• Potting mix: Choose a fertile, loose mix that holds useful moisture without becoming dense.
• Light: Give it abundant bright daylight but shield the foliage from prolonged harsh sun.
• Temperature: Keep temperatures around 20–28 °C, with prolonged cold below 15 °C avoided. Keep ‘New Guinea Gold’ warm while it is actively growing and move it away from cold glass or draughts before the temperature falls to 15 °C.
• Humidity: Keep the air around ‘New Guinea Gold’ near 60–80%, with gentle circulation around the foliage.
• Feeding: Use a complete houseplant fertiliser at a moderate dose while new leaves are growing. Feed somewhat more often while growth is strong. Pause further feeding when growth becomes sluggish.
• Repotting: Wait until the roots are filling the present container before giving the plant more pot space.
• Propagation: Rooted offsets and firm corms are the practical propagation routes; establish each one separately in warm conditions.

Common issues with Alocasia macrorrhizos ‘New Guinea Gold’

• Growth slows noticeably after the plant is moved somewhere cooler: Move it back to a reliably warm position and keep the light bright but indirect. Once the conditions are stable again, give the plant time to restart before adding more fertiliser. If growth continues to weaken, check the roots.
• Lower leaves sag and turn yellow while the container stays unusually heavy: Check the roots before adding more water. If the roots occupy only a small area inside a large, wet pot, move the plant to a smaller container that better matches the root system and leave every healthy root in place. Remove roots only where rot is obvious.
• Brown leaf margins keep returning: Check for uneven watering, nearby heat or very dry air, and any salt build-up from water or fertiliser. Deal with whichever cause matches the conditions, then use fresh growth to see whether the brown margins stop returning.

Alocasia macrorrhizos ‘New Guinea Gold’: 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 New Guinea and macrorrhizos mean

Macrorrhizos means “large-rooted”, from Greek makros, “large”, and rhiza, “root”. New Guinea records the cultivar’s Papuan origin near Kavieng on New Ireland.

Trevor Ford collected ‘New Guinea Gold’ in November 1979 from the grounds of the Kavieng Hotel on New Ireland, Papua New Guinea. The plant was traced to a nearby village and taken to Australia. Its New Guinea provenance and the gold colouring on its petioles and leaves account for the cultivar name.