Alocasia ‘Sedenii’

Breeding origin and parent species

Alocasia ‘Sedenii’ is a historic 1869 hybrid of Alocasia cuprea—then listed as Alocasia metallica—and Alocasia longiloba ‘Lowii’. Period sources disagree on whether John Seden or Mr Dominy made the cross at Veitch Nurseries.

Alocasia cuprea is associated with rocky Bornean rainforest slopes at roughly 1,000–1,500 m, including limestone, sandstone and ultramafic ground. Alocasia longiloba ‘Lowii’ comes from a species that also reaches cliffs and boulders but extends into rainforest floor, swamp forest and regrowth at lower elevations.

Care for Alocasia ‘Sedenii’

• Light: Give bright filtered light. Acclimated plants tolerate gentle morning or evening sun; avoid hot midday sun and weak light.
• Watering: Water when the surface begins to dry, checking small pots more often and larger pots deeper. Soak evenly, drain and empty the outer pot.
• Humidity and airflow: Aim for 60–75% relative humidity with gentle airflow. Avoid cold draughts and direct fans.
• Temperature: Keep at 20–28 °C, away from cold windows and draughts. If cooler conditions slow growth, allow more drying between waterings.
• Substrate and repotting: Let a new plant settle in its nursery pot. Later, choose a small pot only slightly larger than the root system. Use fine organic material with plenty of pumice, perlite or another coarse mineral component.
• Feeding: Use a complete fertiliser at one-quarter of the label dose every second or third watering during growth. Feed less often when growth or available light decreases.
• Leaf care: Dust with a soft brush or barely damp microfibre cloth. Do not polish or rub the metallic surface.
• 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 ‘Sedenii’

• 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.

John Seden and Alocasia ‘Sedenii’

‘Sedenii’ is the historic hybrid Alocasia cuprea × Alocasia longiloba ‘Lowii’, introduced in 1869 and named for the Veitch nurseryman and hybridist John Seden.

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.