Troubleshooting
Tunbridge Filmy Fern problems — and how to fix them
Tunbridge Filmy Fern (Hymenophyllum tunbrigense) is generally low-drama, but a few issues come up again and again. Here is what each one looks like, why it happens, and the fix.
Desiccation collapse
The single-cell-thick fronds have no waterproof cuticle and will shrivel and brown within hours if humidity drops — the leading cause of death in cultivation; always grow in a sealed humid enclosure.
Algal and fungal overgrowth
The permanently wet sphagnum substrate and dim conditions encourage green algae and grey mould (Botrytis), which can smother the delicate fronds; improve air circulation slightly by cracking the terrarium lid and remove affected material promptly.
Prevent tunbridge filmy fern problems before they start
Most tunbridge filmy fern issues are care-mismatch, not bad luck. Dial in the basics:
Tunbridge Filmy Fern problems — FAQ
Why is my tunbridge filmy fern desiccation collapse?
The single-cell-thick fronds have no waterproof cuticle and will shrivel and brown within hours if humidity drops — the leading cause of death in cultivation; always grow in a sealed humid enclosure.
Why is my tunbridge filmy fern algal and fungal overgrowth?
The permanently wet sphagnum substrate and dim conditions encourage green algae and grey mould (Botrytis), which can smother the delicate fronds; improve air circulation slightly by cracking the terrarium lid and remove affected material promptly.