UK compost
What compost for wilson's filmy fern in the UK?
Hymenophyllum wilsonii
More about wilson's filmy fern in the UK
Which compost wilson's filmy fern needs
For wilson's filmy fern the mix to buy is peat-free ericaceous (lime-free) compost. Attach the plant to a piece of acid cork bark or a rough, lime-free stone surface with a pad of moist sphagnum moss. Avoid any compost or substrate containing chalk or lime. Rainwater is essential; tap water in hard-water areas will gradually raise pH and kill the plant.In British garden centres the bagged growing medium is sold simply as “compost” (multipurpose, ericaceous, or loam-based John Innes), which is a different thing from the rotted garden “compost” you make in a heap — for a pot you want the bagged kind.
Peat-free compost
Buy peat-free. The sale of peat compost to home gardeners is being phased out across the UK, and the RHS recommends peat-free on environmental grounds. A good peat-free multipurpose grows wilson's filmy fern perfectly well; the one habit to change is watering — peat-free dries faster at the surface while still moist below, so check by feel a knuckle deep rather than trusting the look of the top.
Ericaceous or multipurpose?
Wilson's Filmy Fern is a lime-hater: it needs an acidic, lime-free ericaceous compost. In ordinary (limey) multipurpose it slowly yellows between the leaf veins as it locks out iron. Buy a bag labelled "ericaceous", and in a hard-water area water with rainwater where you can, since tap water is slightly alkaline.
For the full recipe, pH and drainage detail (US wording), see the wilson's filmy fern soil & potting-mix guide.
Compost for Wilson's Filmy Fern in the UK — frequently asked questions
What compost should I use for wilson's filmy fern in the UK?
Use peat-free ericaceous (lime-free) compost. Attach the plant to a piece of acid cork bark or a rough, lime-free stone surface with a pad of moist sphagnum moss. Avoid any compost or substrate containing chalk or lime. Rainwater is essential; tap water in hard-water areas will gradually raise pH and kill the plant. In UK garden centres this is sold simply as "compost" — the bagged growing medium, not garden-made leaf-mould — so match the description above rather than a brand.
Can I use ordinary multipurpose compost for wilson's filmy fern?
No — wilson's filmy fern needs an acidic, lime-free (ericaceous) compost. Standard multipurpose is too limey and will slowly cause yellowing between the leaf veins (lime-induced chlorosis). Buy a bag labelled "ericaceous".
Should the compost be peat-free?
Yes. Sales of peat compost to home gardeners are being phased out in the UK, and the RHS recommends peat-free for environmental reasons. Modern peat-free multipurpose composts grow wilson's filmy fern perfectly well — they dry a little faster at the surface, so check moisture by feel rather than by the look of the top.
Does wilson's filmy fern need grit or perlite added?
Not essential, but a couple of handfuls of perlite in the mix improves aeration and guards against overwatering — useful on a cool, damp British windowsill where compost stays wet longer.
What pot and drainage does wilson's filmy fern need?
Always a pot with drainage holes. Saturated, acidic sphagnum moss on bark or acidic stone. Stand it on a saucer, empty any water that collects after watering, and never leave the pot sitting in a full outer cover — waterlogged compost in a cool UK room is the commonest cause of root rot.
More wilson's filmy fern care
See the full wilson's filmy fern care guide, its UK watering and UK hardiness.