Don’t put away your seed flats and potting soil just yet. It’s time to go on a spore hunt.
Spores are a most useful catch if you want to plant ferns in quantity. But you’ll have to be patient.
Keep your eyes out for pretty ferns, and when you find some to your liking, start checking the undersides of their leaves. Sometime between now and early fall, those undersides will be punctuated with brown spots containing spores. Watch out, though, because when spores are ripe the cases split open to send their dust-like contents all over the place.
When you find fern leaves with plump, firm spore cases on them, you’re in business. Cut off the leaf or part of it and lay it with the spore cases facing down between a fold of paper. Kept in a dry, airy room, the spore cases will release their spores — not all over the place this time, but right onto the paper. Tap these spores into an envelope and they’re ready to sow, or can be stored for later sowing.
Spores are something like seeds of flowering plants, except that seeds have a full complement of chromosomes, the result of the union of egg and sperm cells each having half a complement of chromosomes. Spores each have only half-complements of chromosomes.
Similar to seeds
Still, you can sow spores in almost the same way as you do seeds. Start with a seed flat and some potting soil. The slow-growing spores are easily invaded by other organisms, so thoroughly clean seed flats and then rinse them with 10 percent bleach solution.
Fill the flat with potting soil and firm it in place. Sterilize the soil by laying absorbent paper, such as filter paper, blotting paper or watercolor paper over it, and pour on some boiling water. As the water subsides, pour on some more, then remove the paper and cover the flat with a clean pane of glass.
Once the soil cools, sow the spores. Just dust them over the surface of the soil and replace the glass immediately. Set the flat on a north windowsill, or somewhere else with indirect light and even temperatures. If water is needed, set the flat in a pan of water to soak up moisture from below.
Within one to a few weeks, the surface of the flat will be covered with a green film, then small, heart-shaped structures. These structures are what are going to make egg and sperm cells. When those cells unite, tiny ferns will eventually begin to grow. This could take months.
As the ferns materialize, they need more room. Carefully lift clumps of baby ferns, along with attached roots and soil, and replant them in new seed flats that have been given the cleaning and boiling water treatments. Leave some headroom in the new flats so that the glass can still cover the plants to maintain high humidity for the couple of weeks that the plants need to re-establish their roots.
After a few more weeks of good growth, transplant the babies again, this time to individual pots. With each move, including their eventual move outdoors, let the plants acclimate slowly to new conditions.
Growing ferns from spores might seem like a lot of trouble. In fact, it really takes more time than trouble, and the growing plants take up little space.
And, as mentioned earlier, you end up with a slew of ferns. Think how pretty all those ferns might look in a bed edged with hosta and dotted with color from columbines, perhaps with a clump of lilies poking through to gracefully show off their pale white or orange trumpets.