From our perspective as Bird's Nest Ferns (Asplenium nidus), you must first understand that we do not propagate like many of your other houseplants. We do not grow from stem or leaf cuttings, and we cannot be divided at the roots in a traditional sense. Our central growing point, the "nest," is a single, fragile crown. Damaging it can be fatal. Therefore, our primary method of creating new life is through spores. These are tiny, dust-like genetic packages located on the undersides of our mature fronds. Think of them as our seeds.
Before you begin, you must know when we are ready. Look for mature, healthy fronds on your fern. On the underside, you will see rows of brown, fuzzy, or streak-like patches. These are sori, the clusters that hold our spores. When the sori appear plump and a rich brown color, the spores within are ripe. To harvest, carefully cut a fertile frond and place it spore-side down on a piece of white paper. Leave it for a day or two in a dry, still location. When you lift the frond, you should find a fine brown dust on the paper—that is us, ready for the next generation.
Our spores require a very specific, humid, and sterile environment to germinate and grow. Fill a shallow pot or tray with a moist, soilless, and sterile seed-starting mix. A mix of peat and perlite is ideal, as it holds moisture while preventing rot. Press the mix down firmly to create a level surface. The next step is crucial: sprinkle the harvested spores sparsely and evenly over the surface of the mix. Do not cover them with more mix, as they need light to germinate. Gently mist the surface with water to settle the spores.
Now, you must create a miniature greenhouse. Cover the tray with a clear plastic lid or place it inside a clear plastic bag to maintain 100% humidity. Place the tray in a warm location with bright, indirect light—direct sun will cook us. This is where patience is vital. In several weeks, you will not see tiny ferns, but a green, moss-like layer called a prothallus will develop across the medium. This is the gametophyte stage of our life cycle, where sexual reproduction actually occurs. You must keep the environment sealed and consistently moist during this entire phase.
After the prothallus develops, and if conditions are right, the next generation—tiny sporophytes, which are the actual baby ferns—will begin to emerge. This can take many months. Once they are large enough to handle (about an inch or two tall), you can begin to acclimate them to less humid conditions by gradually opening the plastic cover for longer periods each day. When they have developed several small fronds, you can very carefully prick them out and pot them individually into small pots filled with a well-draining, peat-based potting mix. Continue to keep their soil consistently moist and provide them with the same warm, humid, and brightly lit conditions their parent enjoys.
