Update on the single fern leaf. I had taken it outside during a couple of unusually warm and sunny days to receive some real solar energy. Now we are looking for 10" of snow with a low of -5°F for one night. Old-fashioned winter from about 40 years ago.
This coming fall I would like to divide the large clump into singles provided I can build a suitable raised bed for planting them about 30" apart. The singles multiply rapidly and will spread to about an 18" wide leaf group within 3 or 4 years.