Cystopteris montana aka Mountain Bladderfern

Cystopteris montana is a small fern called mountain bladder fern. Its native range spans temperate Eurasia and subarctic North America. It extends south into the northwestern United States. The RHS lists it as native to Britain and Ireland. In northern England and Scotland, it grows on damp mountain rocks. These sites tend to be basic rather than acid. Recorded sites lie at 2,300–3,600 feet [700–1,100 metres] above sea level.

This deciduous fern reaches about 1 foot [0.3 metres] tall. Its fronds die back rather than staying green year-round. A creeping rhizome lets the plant spread through the soil. The evidence gives no mature width for garden plants. Its small size and spreading form suit woodland garden planting. PFAF values it as an ornamental plant for shaded sites. It lists both dappled woodland shade and shady garden edges.

Choose moist soil that drains well for garden growth. Sandy soil, loam and clay can all support this fern. It prefers a pH of 6.5–7, close to neutral. It also tolerates a wider pH range of 5.5–7.5. PFAF reports growth in both full shade and partial shade. Yet its landscape notes advise against deep shade. A site with dappled light fits both accounts. Plants can withstand up to four hours of direct sun daily. High air humidity helps meet its growing needs. Dry seasons can cause the fronds to die back early. PFAF lists USDA hardiness zones 4–8.

Spring division offers one way to raise more plants. PFAF also gives instructions for growing plants from spores. Sow ripe spores on the surface of sterilized, humus-rich compost. Keep the compost moist while the young plants develop. At 20°C, germination takes about one to three months. Move small groups into pots once large enough to handle. Keep these young plants humid until they become established. PFAF advises waiting two years before planting them outdoors.

PFAF records the root as a food for severe shortages. Its food rating is low, at one out of five. This record should not be read as proof of safety. The source reports no toxicity cases for this species. It does not establish that the plant is harmless. PFAF lists no known medicinal uses or other practical uses.