Alocasia macrorrhizos ‘New Guinea Gold’

Variegation and species origin

Although the cultivar name points to New Guinea, the species extends across a much wider humid tropical range. ‘New Guinea Gold’ is cultivated material from a lineage associated with warm island lowlands and heavy seasonal or year-round rainfall.

Care for Alocasia macrorrhizos ‘New Guinea Gold’

• Light: Give bright indirect light, with gentle morning or evening sun after acclimation. Avoid hot midday sun.
• Watering: Water when the upper layer begins to dry, checking deeper in a large pot than a small one. Large leaves use water quickly, but corms need full drainage.
• Humidity and airflow: About 50–70% relative humidity is usually enough. Keep air moving around the crown, especially where large leaves overlap, and avoid cold draughts.
• Temperature: Keep at 18–30 °C, with roots above 16–18 °C. Avoid sudden chills and cold, wet substrate.
• Substrate and repotting: Let a new plant settle in its nursery pot. Later, choose a pot only slightly larger than the root system. Use a rich, coarse mix of coco coir or peat, medium bark and pumice or perlite.
• Feeding: Use a complete fertiliser at one-quarter of the label dose with most waterings during strong growth. Feed less often when growth or available light decreases.
• Leaf care: Clean one leaf at a time with a soft damp cloth, supporting it from below. Check undersides and petiole joints for pests.
• Propagation: Separate rooted offsets or cormels (small corms) while growth is underway. Divide rhizomes only into rooted sections with a growth point. Use vegetative methods to retain the cultivar or hybrid.

Drooping leaves, root rot and split leaves

• Several leaves yellow or the crown droops: One old yellow leaf is normal. If several change, check the whole root ball: a dry root ball points to thirst; wet substrate with soft roots or a sour smell points to root damage. If the roots are firm, also check light, cold exposure, recent environmental changes, pests, feeding and normal leaf turnover.
• Soft lower stem or a sour-smelling root ball: Pause routine watering while you inspect the plant. Remove only soft dark tissue with a disinfected blade, cleaning it between cuts, and keep firm stem and roots. Repot in fresh, airy substrate, settle the mix once with a small amount of water, then water again only when the reduced root system has used enough moisture and the upper layer begins to dry. A mostly soft lower stem rarely recovers.
• Fine pale speckling or webbing: Spider mites gather beneath the leaves and along the main veins. Isolate, inspect every underside, rinse with lukewarm water and dry away from sun. Apply a labelled spider-mite product exactly as directed.
• Silvery scars, distorted leaves or black specks: Thrips feed inside rolled leaves. Isolate and inspect new leaves, sheaths and undersides. Remove only badly affected leaves when necessary, then apply a labelled thrips product as often as directed.
• Brown leaf margins: Check for dry pockets, low humidity, heaters, strong draughts and fertiliser salts. Correct uneven moisture, move the plant away from heaters and strong airflow, and flush accumulated salts with low-mineral water. Do not keep the roots wetter to raise humidity.
• Bleached tan patches or dark water-soaked areas: Dry damage on the window-facing side often points to sun scorch; dark translucent patches after contact with cold glass or a cold draught are consistent with chilling. Move the plant to stable bright filtered light. Reintroduce only gentle morning or late-day sun, and only where suitable, after gradual acclimation. Remove fully dead tissue.
• Spots that enlarge or develop yellow halos: Wet leaves, saturated roots and still air can favour leaf-spot problems. Isolate the plant, keep the leaves dry and improve airflow. Remove only badly affected leaves when necessary, using a disinfected tool and cleaning it between cuts. Obtain a reliable diagnosis before applying any disease-control product.
• A leaf stalls or successive leaves shrink: Check for dry pockets or damaged roots, then assess warmth, light and humidity. Never pull the leaf open. If growth slows while the roots and stem remain firm, reduce watering only when the substrate is drying more slowly; do not let an already dry root ball become drier.
• Petioles buckle or leaves split: First rule out dry or rotten roots. Clean splits without spreading spots usually come from contact, handling or strong airflow. Give the crown space, move the pot carefully and support only an unstable petiole.

Pet safety for Alocasia macrorrhizos ‘New Guinea Gold’

• Not pet-safe.
• Calcium oxalate crystals in the plant can cause immediate pain and irritation when a pet chews it.
• Contact a vet promptly if a pet drools, vomits, develops swelling of the mouth or tongue, or has difficulty swallowing.

How Alocasia macrorrhizos ‘New Guinea Gold’ got its species name

The epithet macrorrhizos combines Greek makros, “large” or “long,” with rhiza, “root.” The name means large-rooted; its doubled r preserves the Greek compound. The genus name Alocasia combines Greek a-, “without” or “lacking,” with Colocasia. Heinrich Wilhelm Schott established it as a section of Colocasia in 1832. George Don raised it to genus rank in the 1839 third edition of Robert Sweet’s Hortus Britannicus, page 631.

Carl Linnaeus first published the species as Arum macrorrhizon in 1753 in Species Plantarum, page 965. George Don transferred it to Alocasia as Alocasia macrorrhizos in 1839 in the third edition of Robert Sweet’s Hortus Britannicus, page 631.