Alocasia portei aka Malaysian Monster

Alocasia portei is a large evergreen plant in the arum family, Araceae. It comes from Luzon in the Philippines. There it grows in wet forests with humid air. It forms upright clumps and grows from a rhizome. Another name for this species is Alocasia regnieri. Gardeners grow it chiefly for its large, deeply cut leaves.

The RHS lists a mature height of 13–26 feet [4–8 metres]. Its spread reaches 5–8 feet [1.5–2.5 metres]. Wild plants can exceed 20 feet [6 metres] in height. Plants stay smaller in pots, though the source gives no firm range. They take 10–20 years to reach full size. The stem base can reach 1.3 feet [0.4 metres] across. Long, arrowhead-shaped leaves have deep cuts along their edges. Their dark green upper sides show pale green veins. Leaves can reach 5 feet [1.5 metres] long. Green leaf stalks bear brown patches and reach the same length.

Each flower structure has a pale pink-cream spathe around a spadix. The spathe forms a sheath; the spadix forms a central column. Bright orange berries can follow if fertilisation takes place. The flowers and fruit draw less attention than the leaves. The RHS recommends this plant for homes, conservatories, and greenhouses. Its large leaves and upright form need ample room.

Give it bright, filtered light and shelter from harsh conditions. The RHS rates it H1A, requiring glasshouse warmth throughout the year. It prefers temperatures of 18–25°C. Use an airy mix that holds moisture but drains well. The soil should be acidic or neutral. During growth, let the top 2 inches [5 centimetres] dry before watering well. Do not leave the pot standing in water. Use room-temperature rainwater where tap water is hard. Feed monthly from April to September with liquid houseplant fertiliser. Reduce watering in winter and pause feeding until spring.

Repot every two or three years; routine pruning is not needed. Divide established clumps or cut the rhizome into sections to propagate. Root each section in its own pot. The RHS reports few disease problems, but poor drainage can cause root rot. Watch for scale insects, red spider mites, and mealybugs under glass. This plant is harmful if people or pets eat it. Contact can also irritate skin and eyes or trigger allergies. Wear gloves and other protective gear when handling it.