Varieties of Fern
There are several ferns which are invaluable for their decorative effect. These includebulbiferum and A. nidus, adiantum (Maidenhair Fern), platycerium (The Stag’s Horn Fern), pteris. Nephrolepis and woodwardia.
bulbiferum is the well-known Spleenwort. This needs a temperature in winter of 7 to 10°C. (45 to 50°F.). Potting should be carried out in March and John Innes No. 1 Potting Compost would be a suitable growing medium. Water must be supplied freely in summer.
This fern produces small plants or bulbils on the veins of the fronds. These can be removed and laid on the surface of a mixture of 2 parts moist peat and 1 part coarse sand in a seed box. The bulbils can be held close to the compost in the box with bent pieces of wire. If they are kept moist and in a temperature of 16°C. (60°F.), roots will soon develop. The small ferns can be potted into 2-in. pots of John Innes No. 1 Potting Compost.
Asplenium nidus, the distinctive Bird’s Nest Fern with undivided fronds up to 4 ft. long and 8 in. wide, is a plant which needs more heat – not less than 16°C. (60°F.) in autumn and winter, rising with sun heat during the rest of the year. Shade from strong sun must be provided. A suitable compost consists of equal parts coarse peat and sphagnum moss.
This species is increased by means ofwhich can be germinated on fine peat and brick dust and kept shaded under a glass covering. The compost should be sterilised at least 12 hours before sowing by scalding it with boiling water.
There are various adiantums or Maidenhair Ferns which can be grown in shady positions in heated and unheated. For the former, heated to 16 to 18°C. (60 to 65°F.), Adiantum cuneatum, A. decorum and A. Williamsii are suitable, for the latter A. capillus-veneris, A.pedatum and A. venustum.
Adiantum cuneatum and A. decorum can be moved to rooms in the home for limited periods provided they are placed in cool, well-lit positions but without direct sunshine falling on them. To maintain good health the atmosphere must be kept moist, which is possible in the greenhouse but more difficult indoors.
The three species I have named as suitable for an unheated house must also be given humid atmospheric conditions. They are not difficult to grow well and can be progressively potted on to make large specimens. Potting should be done in early spring using John Innes No. 1 Potting Compost. Water should be supplied freely from April to August and moderately for the rest of the year when growth is less active.
Adiantums can be increased by dividing the crowns of the plants between March and April. This must be done carefully to avoid damaging the fronds and roots, preferably with two hand forks placed back to back and then prised apart, as one would divide herbaceous plants with garden forks. Spores can also be germinated as recommended for Asplenium nidus but this is a much slower process.
The platycerium or Stag’s Horn Fern (the common name is really appropriate) is an imposing plant for the greenhouse whether grown in pots or, even better, on a piece of bark or wood. All the platyceriums except one, Platycerium bifurcatum (syn. P. alcicorne) need really warm greenhouse conditions but this fine species is perfectly happy in a cool greenhouse.
The most satisfactory form of display, as I have indicated, is to suspend the plants on bark or wood from the roof or sides of the greenhouse. The roots should be covered with a layer of sphagnum moss and fibrous peat, these being retained in position with pieces of copper wire. Topdressing with the same materials should be done in February or March.
Water should be given freely from April to September and moderately for the rest of the year. Shade must be given from direct sun but this plant needs good light.
Platycerium bifurcatum is increased by division in spring as with adiantum.
The pteris are popular ferns for the cool greenhouse, especiallycretica which has pretty fronds up to a foot in length, and the handsome ensiformis victoriae with variegated foliage. This last needs shade from strong light to get the best effect from the variegation and Pteris cretica needs shade in summer.
Pteris should be potted in March using John Innes No. 1 Potting Compost. In spring and summer they need plenty of water but less during the other seasons. A winter temperature of 7°C. (45°F.) is desirable.
Pteris are increased by division in spring, carried out with care to avoid damaging the roots and fronds.
The nephrolepis are ferns noted for their beauty and desirability as hanging basket plants. One, Nephrolepis exaltata, the Ladder Fern, has exceptional appeal with its arching fronds over 2 ft. long. This fern needs a winter temperature of 13 to 16°C. (55 to 60°F.).
Potting should be carried out in February or March using John Innes No. 1 Potting Compost. Water should be given freely from April to September and moderately during the rest of the year.
Increase is by division of the crowns between February and April.
Woodwardia radicans is a delightful fern to grow in a cool or, and may even be grown out of doors in sheltered gardens if covered with bracken fronds or similar protective material during winter. It is best of all planted out in a greenhouse border, when the fronds reach 5 or more feet in length but it can be grown in pots or hanging baskets, in which case the fronds are much shorter.
Increase is by bulbils, as described for Asplenium bulbiferum, or by division of the crowns.