At Nasami Farm, we welcome horticultural challenges.  At this time of year, while our plants enjoy their winter slumber and our seed trays accumulate cold days, we turn our attention to fern propagation.  We choose not to acquire plugs from a tissue culture lab growing clones by the thousands.  Instead we grow them the old-fashioned way -- from spores.

Ferns are peculiar.  They are some of the most archaic forms of plant life on earth, closely related to mosses. They differ in their plumbing having evolved a vascular system for moving water and nutrients throughout their fronds.  Not capable of flowering, they produce spores as a means of reproduction, typically in small bubbles (called sori) on the undersides of fronds.  When ripe, sori burst open, spreading millions of dust-like spores on the breeze.

Spores are shed from late June, as with the interrupted fern (Osmunda claytoniana,), through late December’s climbing fern (Lygodium palmatum).  Timing spore collection can be tricky as they may be completely shed in only a few days.  Entire fronds are harvested just as the sori are erupting and placed in envelopes to dry.  Once dried, the spores are carefully separated from the chaff.  This is a very delicate process as an untimely sneeze can send all the spores airborne. 

Once the spores have been separated and cleaned, the process is quite easy, but time-consuming.  Spores are gently dusted over moist, sterilized germination media, and placed in sealed plastic bags in a dimly lit location for a month or two.  During this time, the spores germinate and start to produce coral-like structures only a single cell thick, ultimately resulting in a heart-shaped growth called a gametophyte.  Once large enough, these moss/algae-looking ferns are misted with water to allow for the exchange of genetic material.  Within a month, a tiny volcano forms in the center of the heart-shaped growth, finally turning into a frondlet or a sporophyte.

After a few months of growth, the frondlets are gently separated and potted into plug trays and kept under domes to keep the humidity up.  Once large enough, the domes are gradually removed as the ferns get acclimated to ambient conditions.  When large enough, the plugs are potted into large pots for finishing.  Some fast-growing species will be ready for garden installation the following fall, while some slow-growing species such as Christmas fern (Polystichum acrostichoides) and royal fern (Osmunda regalis var. specatbilis) may take two full growing seasons to achieve a suitable size.