UK compost
What compost for giant dorstenia in the UK?
Dorstenia gigas
More about giant dorstenia in the UK
Which compost giant dorstenia needs
For giant dorstenia the mix to buy is peat-free multipurpose compost cut roughly half-and-half with horticultural grit or perlite. Use a quality cactus or succulent compost blended with 30–40% additional pumice, perlite, or coarse gravel. Dorstenia gigas is native to alkaline limestone cliff substrates; a neutral to slightly alkaline pH (7.0–7.5) suits it better than acidic mixes. Excellent drainage throughout the pot depth is essential.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 giant dorstenia 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?
Giant Dorstenia does not want a rich, water-holding compost — it wants sharp drainage. Cut peat-free multipurpose roughly half-and-half with horticultural grit, sharp sand or perlite, and always pot into a container with drainage holes. A "cactus and succulent" bagged mix is a ready-made shortcut.
For the full recipe, pH and drainage detail (US wording), see the giant dorstenia soil & potting-mix guide.
Compost for Giant Dorstenia in the UK — frequently asked questions
What compost should I use for giant dorstenia in the UK?
Use peat-free multipurpose compost cut roughly half-and-half with horticultural grit or perlite. Use a quality cactus or succulent compost blended with 30–40% additional pumice, perlite, or coarse gravel. Dorstenia gigas is native to alkaline limestone cliff substrates; a neutral to slightly alkaline pH (7.0–7.5) suits it better than acidic mixes. Excellent drainage throughout the pot depth is essential. 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 giant dorstenia?
Not on its own — multipurpose compost holds too much water for giant dorstenia and will rot the roots. Cut it roughly 50:50 with horticultural grit, sharp sand or perlite so it drains fast.
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 giant dorstenia perfectly well — they dry a little faster at the surface, so check moisture by feel rather than by the look of the top.
Does giant dorstenia need grit or perlite added?
Yes — giant dorstenia must have sharp drainage. Add about one part horticultural grit or perlite to one part compost, and always use a pot with drainage holes.
What pot and drainage does giant dorstenia need?
Always a pot with drainage holes. Well-draining mix with added aggregate — 30% extra inorganic content. 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 giant dorstenia care
See the full giant dorstenia care guide, its UK watering and UK hardiness.