To start with, find a fertile frond of the species you want to propagate. Fertile means that the sori on the back of the frond are ripe.[image] Ripe usually means srongly colored, but which color depends on the species. With woodferns it is black, in Polypody orange-brown. If you look with a lens you should see that some sporangia have opened, but many have not. Pick the frond, or at least some of the fertile pinnae. Press it between pieces of clean paper (e.g. generic printer paper) for a few days with the spore side down, say inside a large book, with some weight on it, say a large book. Later open the press and carefully remove the frond. If you were successful you should see a delicate image of the frond laid out in spores.

Prepare the growth medium, maybe beforehand. I use a half inch layer of finely sifted compost in a pie plate. Some growers sow directly onto a small flower pot. Some sow onto an inorganic substrate. The growth medium should be sterilized by e.g. a few minutes in a microwave. It should also be moist.

Carefully pick up the paper with the spores, and hold it vertical to allow any chaff to slide off. Then hold it spore-side-down over the prepared medium and tap or snap top of paper to realease spores. Don't scatter them too densely. Immediately cover the growth medium, perhaps with plastic wrap, and put inside a ziplock plastic bag. If using a small flowerpot you can cover the top and just put the base in a dish which you keep watered.

Put the spore covered medium in a warm bright location, but not ever in direct sunlight. Open the seal and spray more water every two weeks.

In a month or four you should get a greenish fuzz covering the growth medium. Continue to mist with water. In another few months you should see individual prothalli, the gametophyte stage of the fern. Some months later you should see the sporophyte stage emerge here and there among the gametophytes. If this does not happen, try misting more heavily, as fertilization requires a film of water for the sperm to swim through. When the sporophytes become dense, or are half an inch tall, transplant them into pots or at least another sealed growth medium. Some say take nickel-sized pieces rather than individual sporelings. Keep covered and moist.

When plants are larger they can be weaned from the high humidity environment. Hardening them is one of the riskiest stages of the entire process. Do it slowly.

If you have performed these steps successfully, you may have 100 baby ferns, perhaps more than you need. Even after the losses from hardening failures, you may have enough to give some away.