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How to Propagate and Grow Ferns from Spores

Ferns, Fungi and Mosses do not produce flowers. Therefore they cannot produce seeds.
They reproduce with spores that form on the underside of the fronds.
Propagating ferns with spores is a fun and fairly easy method of growing new plants,
but it can take up to a year before you see any sign of life and 2-3 years
before your new ferns are ready to be planted in the garden.

What are Spores?

Shaun the Garden Gnome Spores are the reproductive cell structures of Ferns, Fungi and Mosses. Fern spores develop inside small green capsules on the underside of the fronds, called sporangia. When the powdery spores are sown on a damp soil mix they produce small, heart shaped growths called prothallia. Each prothallus contains both male and female organs, allowing them to reproduce and thus create tiny new ferns.

Collecting and Drying Your Fern Spores

Spore bearing fronds should be harvested in mid to late summer after the majority of the sporangia have ripened. The sporangia swell and turn brown, black, blue or orange, depending on the species, when they are almost ready to shed their spores. If the sporangia appear hardened and rough, they have more than likely already done their thing.
Remove a section of a mature, fertile frond using a clean, sharp knife or razor blade.
Place the section of frond in a manila envelope and keep it in a warm room for 4 or 5 days. Be sure to label the envelope carefully if you are propagating more than one type of fern.

Preparing the Growing Medium for Growing Spores

All planting material, tools, trays and pots should be sterilized prior to use, in order to ensure success!
Begin preparations 24 hours before you are ready to sow your spores.

Select a tray or any standard pots that can fit in a clear container that can be sealed.
You can even use large, zip lock bags if you only have a pot or two.
I personally recommend using 4" plastic pots set in a seedling tray and placed in a sealed propagating case
made from a 10 or 20 gallon aquarium and covered with a clear piece of plexiglas to seal in humidity.
A good planting mix should consist of sifted peat moss or compost
with a generous amount of coarse perlite or pumice added for drainage and aeration.

Sterilize Your Tools, Trays and Soil

If you are using pots or flats that have been used previously, you will need to clean them thoroughly, then sterilize them by dipping them in a solution of 1-2 tablespoons of household bleach to each gallon of water. Allow them to dry thoroughly.

The growing mix will need to be sterile as well, to kill off any competing spores that may be present in the medium.
Probably the easiest way of sterilizing the soil is to fill the pots or trays with growing mix,
cover them with a towel to prevent washout, then carefully pour boiling water over the entire surface
until the mix is thoroughly saturated. Allow the mix to cool completely.

You can bake your mix in the oven... if you can deal with a little unpleasant smell. Preheat oven to 200 degrees. Place the growing mix into a turkey sized baking bag and tuck the open end under. Lay it flat on a large cookie sheet. Poke several holes in the top of the bag and press a meat thermometer in the center. Bake until the soil temperature reaches 180°, then allow it to cool in the oven. Re-wet the mixture completely, using distilled water.

If you plan to do much spore propagation in the future (or seeds for that matter), pick up a $20 microwave oven at Goodwill.
Fill a bowl with growing mix, pop it in the oven, and nuke it until its steaming! Allow mix to cool in the microwave. Re-wet the mixture completely, using distilled water.

After filling the pots or trays with moistened medium, tamp them well to remove any air pockets and firm the soil!

How to Sow and Grow Fern Spores

The Teacher By now, the fronds that you put in the envelopes have dropped most of their spores. Gently shake the envelope to get all of the spores to fall down to the lowest corner.
Cut off the corner of the envelope to create a triangular, 3"-4" spore pouch that will be helpful for sprinkling your spores evenly.
Remove any large pieces of debris from the pouch by hand or with tweezers.
The layer of fine, brown dust remaining is the spores!

Spread your spore pouch open enough that you can monitor the movement of the spores as you sow them. Hold the pouch with the creased edge down, at a 45° downward angle. Tap on the top of the pouch lightly to slowly move the spores down the trough, and spread them sparingly across the soil surface. Do not overcrowd them!

Seal the planters with plastic wrap or container and keep it in a warm, bright (not full sun) place where they can remain, undisturbed for the next several months to a year (depending on the species). Fluorescent lights will work fine at this point.
Monitor the moisture of the growing mix to be sure it remains evenly moist. If the mix begins to dry out, mist it or bottom water with room temperature, distilled water. A properly sealed container will seldom, if ever need watering.

From Spore to Prothallia to Plantlets

From this stage on, warm (72°-75°) constant humidity is essential for success. Bottom water only!
Typically, in 6-9 months a green, moss-like growth will develop. These are the prothallia... thin, green, heart-shaped structures with minute, hair-like roots, that are the first stage of growth for your new ferns.
Prepare a new container with moistened, sterile planting mix. Lift small, ½" sections of the prothallia with a flat knife and press them gently into the surface of the soil in the pot spacing them about an inch apart. Return them to your propagating case.

Small plantlets will begin to develop from the sections of prothallia that will form small fronds. Once plantlets have developed several true fronds you can pot up the healthiest ones into cell-packs or small pots, and cull any that aren't thriving. After they have grown several more fronds, move them up to 3 or 4 inch pots for growing on. Return them to your propagating case.

Hardening Off Your New Ferns

In about another year, your ferns will be ready to move into larger pots for tender species or into the garden for hardy ferns.
Your ferns have lived a very pampered, luxurious life style up until this point and will need to eased into the reality of the world beyond their propagation case gradually. Begin by opening the case in stages to get them accustomed to less humidity before removing them completely.
Ferns that are going to be planted in the garden should be allowed to the temperature changes by only putting them outside for a few hours during the warm part of the first day, increasing the exposure time each day.
NEVER move any plant straight into full sun!
Have fun, Good luck!
Fern Sporangia and Spores
Sporangia Containing Spores on the underside of a Fern Frond