Ferns are basically propagated from spores, and these are not the equivalent of seeds. I he fern plant itself is an asexual stage in the life history of a fern: it produces spores, which are themselves asexual. The spores are dispersed and germinate, producing the sexual stage, which is called a prothallus. This is a small heart-shaped, green, scale-like growth with male and female organs, which fertilize. It is at this stage that the fern as we recognize it begins to develop.
Thus, to propagate ferns it is necessary to collect and sow spores under such conditions that the prothallus and subsequently the young fern plant will be capable of developing. Dampness and high humidity are the conditions required for the prothallus to fertilize.
As soon as a cloud of spores is produced when a fern frond is tapped, they are ripe and ready for sowing. When this stage is reached, cut the frond and plac^ it in a large dean paper bag. Then keep it in a warm dry place for a day or so, occasionally shaking it vigorously to detach the spores, which will collect in the bottom of the bag. Never use the same paper bag twice; otherwise the spores may become mixed up with any residual ones already in the bag.
Make up a compost of 8 parts (by volume) sifted peat and 2 parts sterilized loam to give it body and 1 part crushed charcoal to keep it smelling sweet.
Choose a clean sterile pan (dwarf pot)— ¡usually of 5} in diameter—and lightly fill it with compost. Strike off the compost and then firm it down about f in below the rim with a presser board. Dress the surface of the compost with a thin layer of finely crushed brick before lightly sprinkling the spores over it. Then cover the pan with a pane of glass and stand it in a saucer containing soft water such as rain water. Place the pan in a warm (21°C/70°F) shaded environment and ensure that the water level is always maintained near the top of the saucer.
In three to four weeks the tiny prothalli will appear and cover the surface of the pan like a growth of liverwort or moss. At this stage the pan must be kept moist, as it is imperative that a moisture film is maintained so that fertilization can occur. Even a short period of drying may prove disastrous. As sciarid flies can also become a problem it is important to keep the pane of glass on top of the pan.
Within seven or eight weeks the small fronds of the fern proper should have appeared on the prothalli. At this stage, remove the glass to allow the fronds to develop hardily and to allow drier conditions, but still keep the pan in a warm (21°C/70°F) environment.
When big enough to handle, lift out each clump and plant it in a seed tray in a peat-based or ericaceous compost. Then grow on in a cold frame until the ferns can be separated easily and potted on.
This technique should work for most hardy ferns and indeed for many of the warm temperate ones.
1 Fill pan with compost. Add layer of finely crushed brick. Sprinkle spores lightly over the surface.
2 Cover pan with glass. Stand in a saucer filled with rain water in warm (21°C/70°F) shaded area.
3 Keep pan moist at all times. Do not remove glass when prothalli appear.
4 Remove glass once small fronds of fern develop, but still keep the pan in a warm environment.
5 Prick out clumps of ferns when big enough to handle. Plant in a seed tray and place in a cold frame.
6 Separate each fern plant when it can be handled easily. Prick out into individual pots.
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