If you’ve been to our alpine garden, you have probably noticed the most fantastic (possibly the best you have ever seen) display of Adiantum aleuticum var. subpumilum. This plant is basically a dwarf version of our Western Maidenhair fern, Adiantum aleuticum, but only reaching 6 to 8 inches in height. Due to its compactness, it works well in rock garden settings or even in containers such as troughs. When I saw this plant for the first time, I had to have it for my own garden. But, this lovely plant is rarely seen in the trade and it is not easy to come by.
This is one of the reasons I decided to grow them from spores. I had never grown ferns from spores before, so I read up on Hardy Fern Foundation’s propagation page (https://hardyferns.org/propagation/). This page has some very helpful pictures, and I highly recommend it to anybody who is interested in growing ferns from spores.
I collected the spores in the August of 2020. I left the fertile fronds on a white sheet of paper, and in a few days, a dusting of brown spores had been released onto the paper. I sowed the spores in a plastic container (like the ones strawberries are sold in). For the soil, I used a mixture of our potting soil and peat. I bottom soaked the container, closed the lid, and placed it on the heated bench in our greenhouse with extended light. It took about three weeks to see a carpet of green on the surface of the soil, and eventually the tiny fronds (which didn’t look anything like Adiantum) appeared. When they were big enough to handle, in February of 2021, the clumps of sporelings were transplanted to a shallow tray. Six weeks later, they were transplanted into band pots, which are tall narrow pots (2.5×2.5×5) with open drainage.
Since sowing the spore, they have become big enough to be potted in half gallon containers, and they will be ready for sale next year. I ended up with 125 plants. I never expected my first spore experiment to be this successful, and this is hugely thanks to the instruction that was provided by the Hardy Fern Foundation. Propagation is kind of addictive because you can make one plant into hundreds!
As for my own garden, I plan to plant a dwarf Adiantum this fall in my miniature garden bed, along with Shortia soldanelloides and Rhododendron impeditum. Just imagine pairing this Adiantum with miniature hostas, or dwarf polygonatum species, such as Polygonatum humile or P. hookeri. At the RSBG, you can find Adiantum aleuticum var. subpumilum paired with dwarf Rhododendron mucronulatum and Cassiope species in a hypertufa trough on the Terrace of the Rutherford Conservatory. The possibilities are endless.
Happy gardening!