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Growing Ferns from Spores by William Cullina
Raising ferns from spores is surprisingly easy if you obtain clean, viable spores and sow them in a sterilized potting mix enclosed in a plastic bag or similar container. The following step by step guide will take you through spore collection, sowing and care of your young hardy ferns.
With a few exceptions, fern spores ripen in covered structures on the underside of some or all of the fronds. Species in the genus Osmunda as well as ostrich and sensitive fern produce modified leaves or leaflets that harbor the spores.
Athyrium filix-femina (lady fern) Osmunda claytoniana (interrupted fern) Matteuccia struthiopteris (ostrich fern) Ripe spores emerging from sori ripe spores are in fertile leaflets “feathers” (fertile fronds) with spores
Each species ripens at a particular time in the season. Interrupted fern is the first in early May while climbing fern ( Lygodium palmatum ) doesn’t ripen until late November. Spores turn from white or green to brown or black when mature, so check the fronds and watch for darkening spore capsules (sori). As the spores are about to drop, the sorus splits open and peals back, revealing tiny globes full of spore. This is the time to harvest the frond. It requires a bit of diligence to catch some ferns at the right time, though others like the Diplazium pycnocarpon (glade fern) pictured to the left ripen over three or more weeks, making timing easier.
Clip the frond and bring it indoors immediately if possible. If you are on a hike or travelling, place it in a plastic bag and keep it in the refrigerator until you get home - it should stay in good shape for up to a week under refrigeration. Find a room that is quiet and free of drafts and place the frond spore side down on a sheet of waxed or white paper and leave it to dry overnight. When you lift the frond off the next day, you should see a brown spore print on the paper. If the print is very faint or non-existent, you were either too early or too late so try again.
Glade fern fronds on paper. The next day with fronds removed The clean spore from these two fronds and a nice spore print visible. with a penny for comparison: this pile contains roughly 10 million spores!
Store the clean spore in a waxed or paper envelope in the refrigerator until you need it. With the exception of the Osmundas and a few other more primitive ferns which need to be sown right away, spore will stay viable like this for several years.
Store spores the refrigerator A packet of wood fern spore ( Dryopteris marginalis ) from the NEWFS seed catalog is enough for 1 pot
eggs grow into what we think of as the fern. This type of reproduction is more sensitive to environmental conditions than that of seed plants, which is accomplished within the flower and ovary. This is way ferns do so well in a sealed plastic bag where the environment is fairly controlled. A temperature between 65-75° F is best.
Lady fern gametophytes 11 days after sowing. Lady fern gametophytes 21 days after sowing.
Lady fern gametophytes 42 days after sowing. Detail of Blechnum spicant (deer fern) gametophyte.
Lady fern gametophytes 93 days old with first sporophytes (young ferns) visible center right (the round-leaved fern center left is a Pellaea atropurpurea (purple cliff brake) that got as a spore in during cleaning).
If no young ferns are evident among the gametophytes after 12 weeks, try watering the pot with dilute liquid fertilizer (1/4 the recommended rate for houseplants). Often this spurs sperm release and fertilization. Leave the ferns in the bag until the young ferns (sporophytes) are 1-2 inches tall. As long as things were sterile from the start and you collected and cleaned the spore correctly to minimize contamination, the little ferns can grow in the bag for up to a year if necessary though you will want to give them additional fertilizer at the same rate once a month.
