Growing Ferns from Spores
Growing ferns from spores is a fascinating and rewarding way to raise new plants. It takes a little patience, but the process is straightforward and you don’t need specialist equipment to get started.
Most ferns reproduce from spores rather than seeds—in fact, no ferns produce true seeds. Spores are held in small, spherical structures called sporangia, grouped together in patches called sori, usually on the back of the frond. The position and appearance of the sori can also help identify the genus and species of a fern.
A Dryopteris species showing ripe sori on the back of a frond.
1. Collect your spores
Start with a frond whose sori are just beginning to release their spores. Ideally, the spores you collect should be free from contamination by fungi, mosses and spores from other ferns.
In many ferns, the sori are protected by a covering called an indusium. When this begins to separate and roll back, the frond is ready for collection.
For ferns without indusia, look at the colour of the sori. Pale or green sori are generally too young, while dark brown sori are probably too old and may already have released their spores.
Place the frond on a sheet of white paper somewhere warm, dry and free from draughts. After about 24 hours, carefully lift it away. Spores and some chaff should be left on the paper.
Gently tilt the paper and much of the chaff should roll away, leaving the spores behind. Tap them into a paper or aluminium foil envelope to store somewhere cool and dry, or sow them straight away.
Spores left on a sheet of paper ready for sowing.
2. Sow your spores
Giving your spores a clean start will improve your chances of success, so use sterile compost and keep it free from contamination after sowing.
Compost can be sterilised by pressure cooking it in a heat-resistant container, drenching it with boiling water or microwaving it while wet. Microwaving is the easiest method.
Place a small amount of good-quality compost and a little water in a transparent plastic or polycarbonate container. Microwave it for long enough to produce steam; the exact time will depend on the amount of compost.
Allow it to cool to room temperature, tap a small quantity of spores over the surface and close the lid.
Fern gametophytes and a few small sporophytes.
3. Care for your spores
Keep the boxes somewhere bright but out of direct sunlight. As a general rule, tropical and indoor fern spores should be kept at 15 °C or above.
Check the boxes every couple of weeks for fungal infection, moss or algae. Small patches of fungal infection can be carefully removed before they spread. Always sterilise any tools you use.
Another option is to remove small ‘plugs’ of healthy gametophytes and replant them in sterile compost.
Algae can indicate that the compost is too wet. Excess moisture can be carefully ‘wicked’ away with a piece of kitchen paper. Moss can also be removed if it starts to compete with the gametophytes or sporophytes.
Young sporophytes potted up and ready to grow on.
4. Grow on your young ferns
This is where patience starts to pay off. Gametophytes can begin to appear from around one to six months after sowing. They are often heart-shaped and around 5–10 mm across, although they may also be filamentous, ribbon-shaped or strap-shaped.
Fertilisation follows and, in time, the first sporophytes appear—he young ferns that will eventually grow into mature plants. This stage can take up to another two years.
Once the sporophytes are a few centimetres tall, replant them into trays or pots. Keep them in sealed containers until they are large enough to be gradually hardened off.
If the boxes need watering during this period, use a fine mist of boiled water that has cooled to room temperature.
