Adiantum raddianum (Delta Maidenhair Fern)

Adiantum raddianum, the Delta Maidenhair Fern, is one of the most beloved of all terrarium ferns, producing layered fans of tiny, fan-shaped leaflets suspended on glossy black, wire-like petioles that create an extraordinarily delicate, floating texture. It originates from the tropical Americas where it grows in permanently moist, shaded ravines and streambanks — the same conditions that prevail in the land zone of a well-built paludarium.

The key requirement for this fern is consistent high humidity; it wilts dramatically if the air dries out even briefly, but recovers quickly once moisture is restored. It is not tolerant of direct sun or drying winds. In paludariums it thrives particularly well near misting nozzles, waterfalls, or in enclosed humid sections, where its fronds maintain their characteristic lacy elegance.

Light: Medium indirect; 1,000–2,000 lux; deep shade causes sparse growth, direct sun burns fronds. CO2/Humidity: No CO2; humidity must remain above 70% at all times; never allow substrate to dry out. Fertilisation: Monthly dilute liquid fertiliser at half strength; avoid fertiliser on fronds. Placement: Plant in rich, moisture-retentive substrate in the shadier, humid land areas of the paludarium. Propagation: Division of rhizome clumps in spring; spore propagation on moist sphagnum is possible but slow.