With hundreds of species to choose from, ferns make a lovely addition to your plant collection. Whether you’re growing warm-climate ferns indoors as houseplants or cold-hardy perennial ferns in a shady corner of the garden outdoors, ferns have so much to offer. Learning how to propagate ferns from spores or mother plants means you’ll always have plenty to share with friends and family. The following excerpt from The Complete Book of Ferns by Mobee Weinstein explains fern propagation techniques and is used with permission from the book’s publisher, Cool Springs Press/The Quarto Group.
How ferns propagate
Propagation is how one fern plant makes more ferns. This happens in the wild as ferns naturally spread and reproduce via spores, and there are simple techniques we gardeners can use to speed up that process and make more ferns to fill our homes and gardens.
Asexual and sexual fern propagation
There are two ways ferns propagate: sexually and asexually (also called vegetative propagation). Sexual reproduction is something I’m sure you are familiar with, though ferns do it a little – okay a lot – differently than animals, namely through their spores. Getting the right conditions for fern spores to germinate and develop into a new fern can be a bit tricky for beginning gardeners, but it is the best way to propagate large numbers of new ferns. Each new plant grown from spores will be genetically a little different, combining traits from both parents, which can be very interesting and fun, particularly with highly variable species such as Japanese painted ferns.
Asexual or vegetative propagation is a lot simpler and can be as easy as physically dividing a pant in half. You’ll usually be able to produce only a few new plants at a time this way, and unlike with sexual propagation, each new plant will be genetically identical (a clone) of the original plant. Here’s more on both types of fern propagation.
How to propagate ferns through spores
In nature, mature ferns produce spores by the thousands, if not millions, every year. Often none or only one or two of those spores will get lucky and land in just the right spot to germinate and produce a new fern. Those odds work for ferns over the long term, but for the gardener looking to produce a batch of new ferns from spores, it is best to give the spores the special care required for a much higher success rate. The process of sowing your own spores isn’t too complex, but it does require some careful attention to details.
Materials needed for fern propagation from spores
- Fern frond with sporangia (spore-producing structures found on the back of the frond)
- White sheets of paper and a heavy book
- Small glass container
- Larger glass bowl for water
- Chlorine bleach
- Clean paper towel
- Compressed peat pellet
- Kettle of boiling water, preferably distilled
- High quality potting soil or vermiculite
- Small piece of plastic wrap
- Rubber band
Step 1: Collect spores
The exact time to do this will be different with every fern. In general, what you’ll be looking for are very dark brown or black raised bumps on the underside of the fern fronds or special dedicated “fertilize fronds,” which aren’t green, but instead very dark brown or black. (Note that at maturity, some species are golden and others are green.) When the sori look ripe, cut the frond off the plant and lay it on a sheet of white paper. Cover the paper with another piece of paper and place a book on top to keep it from moving or being exposed to air movement. Over the next few days, you should see a brown (or gold or green) powder collecting on the paper under the frond. Those particles are the spores! If no spores are released, you might have collected the fronds too early or too late. You can always try collecting fronds at different stages of development until you find the best time for your favorite fern.
Step 2: Sterilize the glass container
To sow your spores, start by sterilizing a small glass container by dipping it in a 10 percent solution of chlorine bleach and water (one part beach to nine parts water), making sure it’s thoroughly washed inside and out. Remove it carefully and set it upside down to dry on a clean paper towel.
Step 3: Prepare the peat pellet
Next, peel the netting back from the center of the peat pellet and place the compressed peat pellet in the sterilized glass container, and pour in boiling water from a kettle. The hot water will cause the compacted pellet to expand and rehydrate and help sterilize the soil. Alternatively, you can put a layer of moist, but not sopping wet, potting soil or vermiculite in the bottom of the glass container (don’t use soil from your garden; it will have too many weed seeds and possible pathogens) and then microwave the container of soil for a couple of minutes to sterilize. After either method, immediately cover the container tightly with a layer of plastic wrap and let cool completely.
Step 4: Sow the spores
When your peat pellet has expanded and cooled, check for standing water. Peel back a corner of the plastic to pour out any excess water. Transfer the spores to a clean, sharply folded piece of paper. When ready, peel back the plastic and gently tap the paper, sprinkling the pores all over the top of the pellet.
Step 5: Cover the container
Immediately re-cover with the plastic and secure with a rubber band. Place it where it will get light (even house lighting) but no direct sun. The sealed container will act like a tiny greenhouse and quickly overheat if direct sun shines on it. If you have grow lights for starting seeds indoors, those will work great. Average house warmth is ideal.
Step 6: Keep the spores moist
Your mini greenhouse should stay sufficiently moist. Seeing some condensation on the inside is a good sign. If it starts to dry out, boil water, cover it as it cools down, and then carefully peel back just a corner of the plastic and pour a tiny bit of the water inside and re-cover immediately. After the first month if you see growth, gently tap on the top of the plastic every couple of days to knock some of the drops of water onto the developing gametophytes to aid in fertilization.
Step 7: Transplant the young ferns
After another month or more, if all has gone well, you should start to see tiny fronds beginning to stick up. These are your baby sporophytes. Once the baby ferns are big enough to handle, transplant them out into individual containers and cover them with plastic wrap. After a few weeks, poke a few tiny pin holes in the plastic. Every 3 to 5 days, poke a few more holes in the plastic. After several weeks your baby ferns should be ready for you to remove the plastic. Keep moving them into bigger containers as they grow, and after 6 months to a year they should be big enough to be planted out in your garden or share with your friends. Remember that every new fern grown from spores will be genetically different, so as they grow, take time to look them over and pick your favorites, which may be the individuals that grow the most vigorously or have the best color in their fronds.
How to propagate ferns through asexual propagation
If you’ve ever come across a big patch of ferns in the woods, you’ve probably seen an example of asexual propagation. Nearly all ferns, after they grow from spores, will begin to spread by means of their creeping rhizomes, one plant growing over time into a whole colony. As a gardener, you can take advantage of this to multiply your ferns quickly and with less fuss than growing from spores. There are several different ways you can propagate ferns asexually.
Fern propagation by division
Physically dividing ferns is the simplest way to propagate them. Simply take a mature clump of ferns out of its container or dig it up out of the ground and divide it into pieces. Every separate clump of fronds – growing on an erect rhizome – can be separated out into an individual plant.
For some creeping species, you can simply pull the clump apart with your hands. Others may have strong rhizomes that need to be cut apart with a sharp knife, pruning shears, or shovel. Once you’ve cut the rhizome, pull the plants apart to untangle their roots.
Once they’re separated, replant each divided section either in containers or in the ground. Be sure to keep new divisions well watered for the first few months after dividing them while they reestablish themselves.
Fern propagation by rhizome cuttings
Fern varieties such as the rabbit’s foot fern, a popular houseplant, that grow long rhizomes on the soil surface or beneath can be cut off to propagate the plant. Cut sections of rhizome that have at least one frond attached and a growing tip and place them on the surface of a pot of moist soil or long fiber sphagnum moss. Keep them shaded and provide high humidity for the best results.
Alternatively, cover the newly planted rhizome with a glass cloche or a plastic beverage bottle with the bottom cut off to keep the humidity high and the soil moist.
Want to learn more about growing ferns?
If you’d like to learn more about the wonderful world of ferns, and how to grow and craft with them, be sure to purchase a copy of The Complete Book of Ferns (Cool Springs Press, 2020). It’s packed with useful and fascinating information about this incredible group of plants.
About the author: Mobee Weinstein is the foreman of gardeners for outdoor gardens at the New York Botanical Garden (NYBG) in the Bronx. She has a degree in plant studies and has done postgraduate work in botany. She taught indoor plants as an adjunct professor at the State University of New York (SUNY) and is a regular instructor at the NYBG.
For more on caring for houseplants, check out the following posts:
- Pilea peperomioides care and propagation
- Blue star fern: Growing tips and care info
- Venus fly trap care
- Caring for air plants