Propagation
As it has become more difficult to obtain commercially grown tropical ferns, especially the less common ones, it is practical to try to increase your own stock and have it available to exchange with other enthusiasts. Propagation is also great fun and it can be very rewarding to produce healthy new plants. There are several methods of propagation depending on the species concerned. Be prepared for some ‘trial and error’ on your way to finding a technique that works for you and your ferns.
Several fern crowns ready for splitting (© Peter Blake)
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Propagation by crown division
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Propagation from bulbils and plantlets
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Propagation from stolons and rhizomes
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Propagation from spores
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Propagation by crown division​
Some ferns grow new crowns (or offshoots) immediately next to the main plant, forming a clump. This can be an attractive feature in a ‘natural’ setting but indoors plants may become very large, crowded and unmanageable. Division can help to reduce the size of the plant, or create new plants to spread around.
A fern crown after splitting and potting (© Peter Blake)
Most indoor and tropical ferns can be divided at any time of year but it is best to avoid doing this during periods of excess summer heat or potential drought or in the depths of winter when growth may be slow. It may be possible to prise an individual crown away with a trowel, but usually the clump will need to be dug up, or removed from its pot, and the crowns prised apart by hand. Occasionally, it is necessary to use a large knife, to split the crowns from each other. Keep some root on all of the separated pieces and be careful not to damage the individual crowns.
A Woodwardia terminal bulbil (© Peter Blake)
When the crowns are split from each other they will have lost some of their roots and will be in a weakened state until they have regrown. So, it is best to pot these up individually and give them time to recover. Generally the conditions should be kept similar to the original plant, but during the period of recovery it is often wise to keep the watering regime constant. The repotted crowns should be kept moist, but not wet, to avoid rot. When they have shown signs of further growth, they can be placed wherever is suitable for them.
Propagation from bulbils and plantlets
Some ferns reproduce vegetatively by producing bulbils or plantlets on the fronds. These either drop off and root in suitable conditions or descend to the ground when the frond collapses and dies. Some ‘walking ferns’ produce a plantlet on the tip of a frond that roots when it touches the ground. These are easy to propagate as the plantlet can be pinned into a pot of compost adjacent to the main plant and then be separated from the original when it is growing well.
Plantlets on the surface of a Woodwardia frond (© Peter Blake)
Ferns that produce bulbils and plantlets on the surface of fronds can be propagated by removing these and growing them in sterile compost in sealed containers until they establish roots and begin to produce fronds of their own. This may take several months, and attention should be paid to ensuring that they remain damp and pest free. It is best to try to separate the offspring from the original frond seems to avoid rot.
Propagation from stolons and rhizomes
Many tropical ferns are epiphytic and live on rocks and trees in places that are either continuously damp or are wetted frequently in storms. Epiphytic ferns most commonly have a creeping rhizome that develops roots to both attach it to the rock or tree and to absorb water and nutrients. These roots generally develop towards the growing tip ahead of new fronds, and rhizomes may have no fronds on them for many centimetres.
Davallia rhizomes (© Peter Blake)
The most reliable method is to pin down the growing rhizome whilst still attached to the main plant. This can be in a pot of suitable compost adjacent to the original plant. When new fronds begin to emerge from this section of rhizome, it is likely that roots have already formed on the underside and that piece of rhizome is likely to be self-sufficient if separated from the main plant. When the rhizome is cut, it may be necessary to reduce evaporation from the fronds by keeping the new plant in a sealed container or plastic bag until active growth is seen.
Another method is used if you are given sections of rhizomes without roots. If there are fronds on the piece, then lay the piece on sterile, damp compost or sphagnum moss in a closed container. Keep this in a bright place out of direct light and be patient. Roots may grow from the piece of rhizome over a few months and active growth at the tip will indicate that the new plant can be gradually hardened off. Eventually, the new plant can be removed from the container and potted up.
A separated section of Davallia rhizome rooting and showing new growth (© Peter Blake)
Terrestrial ferns with creeping rhizomes are best propagated by separating a piece of rooted rhizome from the main plant and potting it up in damp compost. It should then be kept in a plastic bag or container until new growth is evident.
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Stolons are aerial rhizomes most commonly seen in Nephrolepis species and some Goniophlebium species. They are often very long, up to one metre, and the growing tip is small. They can be propagated by allowing the tip to touch damp compost whilst still attached to the main plant. They will not grow from detached pieces of stolon.
Propagation from spores
A defining characteristic of ferns is that most of them reproduce from spores. No ferns produce true seeds. Spores are carried in sporangia, spherical packets that are clustered together in patches called sori, usually on the back of the parent frond. The distribution and appearance of these sori is an important diagnostic feature in determining the genus and species of a fern.
A Dryopteris species showing ripe sori on the back of a frond (© Matthew Reeve)
If you want to grow ferns from spores, then the first thing to do is to obtain or collect spores from a plant you wish to propagate. Ideally, this should be free of contamination by fungal and moss spores, and also by spores of other ferns. If possible, remove a frond which shows sori that are just beginning to shed their spores. Many ferns have sori that are protected by a cover or indusium. If this is just beginning to separate and roll back, then the frond is perfect for collection. If the fern is of a variety that does not have indusia, then the colour of the sori can be a clue as to how ripe the sporangia are. If they are pale or green then they are too young, if they are dark brown, then they are probably too old and the spores will have all been released. If a suitable frond is placed on a sheet of white paper in a warm, dry, draught-free place then it will release spores over a period of about 24 hours. The frond can then be carefully lifted off and the spores and some chaff will be left on the paper. If the paper is very carefully tilted to one side, the chaff will often roll off and the spores will be left on the paper. These can then be tapped into an envelope made of paper or aluminium foil for storage in a cool dry place or used for immediate sowing.
Spores left on a sheet of paper ready for sowing (© Peter Blake)
It is important that the compost used for sowing is sterile and remains free of contamination after sowing has taken place. There are several methods of sterilising compost including pressure cooking in a heat-resistant container, drenching with boiling water, or microwaving wet compost. The latter is the easiest method. Simply place a small amount of good quality compost, with a little water, in a transparent plastic or polycarbonate container. The period of microwaving will depend on the quantity of compost used but it should be long enough for steam to be produced. The compost should then be allowed to cool to room temperature before a small quantity of spores are tapped over the surface and the lid closed.
Fern gametophytes and a few small sporophytes (© Peter Blake)
Once sown, the boxes should be kept somewhere bright but not in direct sunlight. As a general rule the temperature for growing tropical and indoor fern spores should not be less than 15 °C . The boxes should be inspected for fungal infections, and moss and algae growth every couple of weeks. If caught early patches of fungal infection can be carefully removed, with the aim of stopping the infection spreading throughout the whole box. Sterilise any tools you use to avoid spreading infection further. An alternative method is to remove ‘plugs’ of healthy gametophytes and replant in sterile compost. If algae is present it might be a sign that the compost is too damp. Excess moisture can be carefully ‘wicked’ off using a piece of kitchen paper. Moss can be removed if it is competing with the gametophytes or sporophytes.

Young sporophytes potted up and ready to grow on (© Peter Blake)
Gametophytes may appear at any time between about one month and six months from sowing. These gametophytes are often heart-shaped and 5–10 mm in diameter. However, gametophytes can also be filamentous, ribbon or strap-shaped. The fertilisation and growth of a sporophyte may take up to two years more. Once the sporophytes are a few centimetres tall, they can be replanted into trays or pots and kept in sealed containers until they are large enough to be gradually hardened off. It may be necessary to water the boxes over this period and this is best done using a mist spray with room temperature, boiled water.