Adiantum raddianum

Adiantum raddianum, the Delta maidenhair fern, is one of the most popular ferns to grow indoors. It is native to South America and its common name comes from its shiny, dark leafstalks that resemble human hair. It typically grows about 17-19 in tall and up to 22 in wide. In the wild, it is found on forest floors, rock crevices, river banks, coastal cliffs, and basalt banks along trails and streams. The triangular fronds are semi-erect in the beginning then droop gracefully as they age and can be up to 12 in long by 6 in wide. The genus name Adiantum comes from the Greek word "adiantos", meaning "unwetted" (in reference to the leaves).

This plant is hardy down to 5 C, so must be grown indoors in temperate regions. However it may be placed outside in a sheltered spot during the summer months. It requires high humidity, well-drained soil, bright indirect light, and a fairly constant temperature. It prefers neutral or slightly alkaline soil and is suitable for USDA hardiness zones 10 and 11. It can be susceptible to scale and mealybug. The cultivars ‘Brilliantelse’ and ‘Kensington Gem’ have won the Royal Horticultural Society's Award of Garden Merit.

A. raddianum is sometimes considered invasive in Hawaii and French Polynesia.