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.
The members of this genus are popularly known as "Ladder Ferns" or "Fishbone Ferns", chiefly from the shape of the fronds of N. exaltata, the best-known and still most generally useful species. The plants are distinguished by the slender runners or stolons so freely produced from the old stems, by the pinnate fronds, free veins, roundish spore clusters, arising from the apex of the upper branch of a vein, usually near the margin, and by the kidney-shaped or roundish indusium.
N. exaltata, from Tropical America, has been grown for many years as a market plant, and hundreds of thousands are still grown hanging from the rafters in greenhouses. Of late years many charming varieties have arisen, and are chiefly remarkable for their feathery or plumose appearance, many of them being almost "mossy" in character, and of a soft delicate green. Amongst the best of these plumose forms are todeoides, Whitmanni, Amerpohli, Rochfordi or Marshalli, compacta, lycopodioides, and elegantis-sima; while among those with long drooping fronds most suitable for growing in baskets or on elevated rockeries in the greenhouse or stove are Piersoni, Fosteri, davallioides, tuberosa, and Scotti. The last-named is an elegant variety that can be grown to perfection in a 5-in. (48) pot, while it is also effective as a basket plant. For table decorations such kinds as cordata compacta, Duffi, Mayi, pec-tinata, philippinensis, and Wes-toni are valuable. There are also several crested or deeply cut varieties, amongst the best being Westoni cristata, cordifolia tes-sellata, rufescens tripinnatifida, and davallioides furcans (fig. 313) - all beautiful. To these may be added Neuberti, a variety of splendid habit, plants in 6-in. pots being quite 2 ft. across. It is comparatively new, but will become better known. Generally speaking the various species and varieties of Nephrolepis flourish in a mixture of peat, leaf mould, and silver sand. Being natives of the Tropics they require plenty ot heat and moisture in summer, and must not be kept too dry or too cool during the winter season.
The propagation of the numerous feathery varieties of Nephrolepis now in cultivation is fairly simple. As they do not develop spores like the old N. exaltata, they are chiefly raised from the runners that are thrown out from the base of the parent plants, in the same way as Strawberry runners. The old plants are plunged in a bed of sandy peat and leaf mould, and as the runners appear they are pegged down to root. When the young plants arising from the runners are sufficiently advanced they are detached and potted up separately. As to the general cultivation of these feathery Nephrolepis the following advice of an American grower of the "Boston Fern", as N Piersoni is called, may be useful:
"In our experience with several thousand Piersoni plants, we find they require a very rich soil after they get started to grow. We use ordinary Carnation soil, one-half rotted cow manure. After they get the pots filled with roots they will stand feeding often, and at no time should they be allowed to suffer from want of water. Plenty of room and light are also very important. It seems to be the impression that too high or too low a temperature is the cause of sporting back, but we are satisfied this is not the case, having tried them in temperatures from 45° to 75° F. and had no trouble except with a few that got potbound or stood too close to the steam pipe and died out frequently. While we do not pretend to be authorities on this subject, we would advise anyone having any trouble with Pierson Ferns to give them better soil, and see that they never dry out. You will soon have them looking different, and the imperfect leaves may be cut off. Piersoni does not lift well from the bench if very large. If you want fine, large plants, keep them in pots, and plunge the pots in soil or moss".
Fig. 313. - Nephrolepsis davallioides furcans.