Andrew collected samples last autumn, just a few pinnae from each species with ripe sporangia underneath. The spores look like brown dust which you collect after leaving the pinnae in a paper packet in a warm dry place overnight.
Andrew sprinkled some spores onto some damp compost in jam jars, with lids to keep them moist, and left them on a shady windowsill.
Andrew was excited to see that after several months the prothalli had started to produce tiny ferns, just as Martin described. Athyrium filix-femina Lady Fern was the first to develop followed by Dryopteris borreri Borrer's Scaly Male Fern. The young fronds were transplanted into some compost in a propagator on a north facing window sill to grow on and Andrew now has six species developing.