Cyathea atrox - S

About the Cyathea atrox - S

Cyathea atrox, accepted in current taxonomy as Sphaeropteris atrox, is an evergreen tree fern from the mountain regions of New Guinea. The species develops an upright trunk crowned with large, finely divided green fronds. This growth habit gives the plant a robust, distinctive silhouette.

Container cultivation is a practical choice for this tree fern in a cool, bright and humid position. Bear in mind that a mature specimen may eventually require considerably more space. The commercial size S does not, by itself, provide information about the age, developmental stage or trunk formation of the specimen offered.

Characteristics

Origin: This species is native to New Guinea. It grows there in wet mountain habitats, including montane to subalpine grasslands and montane forest margins.

Family: Cyatheaceae, the tree fern family.

Position: Choose a cool to moderate, bright and humid position sheltered from strong winds. A greenhouse or conservatory is suitable; during frost-free periods, the plant can also stand outdoors in a container. A warm, dry living space is less suitable.

Height: A mature plant can form a trunk several metres tall, with fronds that may reach almost 2 metres in length. Growth generally remains more limited in container cultivation. Its current height or developmental stage cannot be inferred from size S.

Flowering period: Not applicable. This tree fern does not produce flowers, but reproduces by spores that may develop on sufficiently mature fronds.

Flower colour: Not applicable, because the species does not produce flowers.

Hardiness: Treat this tree fern as not winter-hardy in the Netherlands. Despite its high-altitude origin, a young or container-grown specimen cannot be considered reliably resistant to a Dutch winter. Overwinter it in cool, bright and frost-free conditions.

Soil type: Use a humus-rich, airy and well-drained substrate that retains moisture without remaining waterlogged for long periods.

Care

Light: Provide plenty of filtered light or light partial shade. In a cool, humid position, the plant can tolerate some direct sun after gradual acclimatisation, but protect it from intense midday sun and a sudden transition to stronger light.

Water: Keep the substrate evenly moist during active growth and do not allow the root ball to dry out completely. Always allow excess water to drain away. Water a little less during cool, slow-growing periods, while still preventing complete drying out.

Fertiliser: During active growth, apply a diluted, balanced fertiliser suitable for ferns sparingly. Reduce or stop feeding when growth slows and avoid strong fertiliser concentrations.

Pruning: Remove only completely dried or damaged fronds. Cut them off carefully at the base without damaging the growing point in the crown or emerging curled fronds.

Repotting: Repot when the roots have largely filled the available pot space. Choose a container only slightly larger, with sufficient drainage holes, and keep the plant evenly moist after repotting.

Humidity: High humidity supports healthy frond development. Combine this with sufficient air movement and keep the plant away from dry, heated air.

Special features: The frond stalks may carry sturdy spines. Preferably wear gloves when moving or repotting the plant and when removing old fronds, and avoid damaging the vulnerable growing crown.