This section is from the book "Commercial Gardening Vol2", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
A very popular genus recognized by roundish or linear sori (i.e. clusters of spores) arranged on the edges of the pinnules or leaflets, forked veins with free veinlets, and usually black shining stems (stipes) and rachis. A peculiarity of the genus is that it is impossible to wet the fresh fronds even by dipping them in water, hence the generic name, which means "dry".
Maidenhair Ferns flourish in a compost of equal parts of loam, leaf mould, and silver sand, but they must not be potted too hard. Established plants like plenty of diffused light but not direct sunshine, and they do not like being watered or sprayed overhead. The best market kind is A. cuneatum elegans, which is always in demand and sells in all sizes from 2½-in. pots upwards. Other good varieties are Collisi, macrophyllum, Victorioe, rhodophyllum, scutum, Pacotti, Legrandi, tinctum, and fulvum. These are compact in growth, and have for the most part deeply tinted fronds.
A. Farleyense, the "Queen of Maidenhairs", is a sterile or almost sterile form of A. tenerum, and is most valuable for its cut fronds. A form of it has recently appeared under the name of the "Glory Fern". Such Adiantums as elegantissimum, trapeziforme, and Williamsi are taller-growing kinds mostly grown in 5-in. pots; while ciliatum, dolabriforme, caudatum, assimile, and Moorei are seen to the best advantage grown in baskets. A. Mariesi is a very useful Maidenhair Fern. It grows quickty, and soon makes strong bushy plants for 3-in. or 5-in. pots. A. fragrantis-simum is another strong-growing form; and A. decorum, with its slightly tinted fronds, is worthy of greater attention for market, as it stands well and is good for cutting.
There is still a good market trade done in cut fronds of A. cuneatum, but not nearly so much as in former years. Asparagus Sprengeri, as well as A. plumosus and its variety nanus, has interfered a good deal with the cut Maidenhair trade, which some twenty years ago was very lucrative. Bunches containing three dozen or four dozen fronds then realized as much as 8d. or 9d., but now half the price is considered good.