Soft Tree Fern / Whe (Cyathea smithii): Cold-Hardy New Zealand Tree Fern with Soft Fronds

Overview

Soft tree fern (Cyathea smithii), known as whe, kaponga, or katote in Māori, is a **cold-hardy tree fern** endemic to New Zealand's subantarctic islands and southern South Island. It develops a slender trunk 10–20 feet tall, crowned with **soft, flexible, tripinnate fronds** 6–10 feet long that lack the harshness of many tree ferns. The trunk is covered in persistent, soft leaf bases. Among the most cold-tolerant Cyathea species.

Cold-Climate Adaptation

• Soft Fronds: Flexible, less brittle than other tree ferns.
• Subantarctic Origin: Evolved for cool, windy, wet conditions.
• Relative Hardiness: Tolerates brief freezes better than most Cyathea.

Culture

Partial shade; cool, moist, humus-rich, well-drained soil. High humidity; shelter from drying winds. Water trunk and crown. USDA zones 9–10 (possibly 8b with protection). Best in cool, maritime climates.

Taxonomic Profile

For a tree fern that laughs at cool, wet winds, the soft tree fern is a subantarctic survivor.