UK compost
What compost for dunn's cape primrose in the UK?
Streptocarpus dunnii
More about dunn's cape primrose in the UK
Which compost dunn's cape primrose needs
For dunn's cape primrose the mix to buy is peat-free multipurpose compost cut roughly half-and-half with horticultural grit or perlite. Use a mix of 50% fine bark, 30% perlite, and 20% quality peat-free compost. Neutral to slightly acidic pH. Never use moisture-retaining potting mixes, as these dramatically increase rot risk.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 dunn's cape primrose 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?
Dunn's cape primrose 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 dunn's cape primrose soil & potting-mix guide.
Compost for Dunn's cape primrose in the UK — frequently asked questions
What compost should I use for dunn's cape primrose in the UK?
Use peat-free multipurpose compost cut roughly half-and-half with horticultural grit or perlite. Use a mix of 50% fine bark, 30% perlite, and 20% quality peat-free compost. Neutral to slightly acidic pH. Never use moisture-retaining potting mixes, as these dramatically increase rot risk. 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 dunn's cape primrose?
Not on its own — multipurpose compost holds too much water for dunn's cape primrose 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 dunn's cape primrose perfectly well — they dry a little faster at the surface, so check moisture by feel rather than by the look of the top.
Does dunn's cape primrose need grit or perlite added?
Yes — dunn's cape primrose 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 dunn's cape primrose need?
Always a pot with drainage holes. Very free-draining, open potting mix. 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 dunn's cape primrose care
See the full dunn's cape primrose care guide, its UK watering and UK hardiness.