Habitat:
Cyrtosperma johnstonii is native to the tropical rainforests of the Solomon Islands and parts of Papua New Guinea. It grows in lowland to mid-elevation humid forests, typically found in swampy or seasonally inundated areas along streams and in alluvial plains. It thrives in warm, shaded environments with consistently high humidity, often rooted in nutrient-rich, water-retentive soils near forest margins.
Description:
Cyrtosperma johnstonii is a striking, large terrestrial aroid known for its bold foliage and architectural presence. Mature specimens can reach up to 2.5 m in height, with thick, upright stems. Leaves are large, sagittate (arrow-shaped), and borne on long, spiny petioles that can extend up to 1.5 m. Leaf blades are deep green, sometimes flushed with reddish tones or dark purple beneath, and can measure up to 1 m in length and 50 cm in width. The petioles and lower stem portions are often marked with dark red spines, giving the plant its dramatic and somewhat formidable appearance. The inflorescence consists of a pale spathe and a robust spadix, although it is rarely seen in cultivation. Cyrtosperma johnstonii is closely related to Cyrtosperma merkusii, but it is distinguishable by its more ornamental foliage and intense spination.
Cultivation:
Cyrtosperma johnstonii prefers warm tropical conditions, with daytime temperatures between 24°C and 30°C and nighttime temperatures of 18°C to 22°C. It requires bright, filtered light or partial shade and consistently high humidity above 70%. Grow in a moisture-retentive but well-draining mix rich in organic matter, such as a blend of loamy soil, compost, and perlite. Soil pH should be slightly acidic to neutral (6.0–7.0). Keep the soil evenly moist, using rainwater or distilled water if possible, and avoid allowing it to dry out. It is best suited to large containers or tropical greenhouse conditions. Fertilise every 4–6 weeks during the growing season with a dilute, balanced fertiliser.
Specifications:
Plant Size: purchased as adult plants. In 12 cm pots
Plant Family: Araceae
Plant Passport: Cyrtosperma johnstonii B 140084 C [user input] D GB