UK compost
What compost for dwarf nasturtium in the UK?
Tropaeolum minus
More about dwarf nasturtium in the UK
Which compost dwarf nasturtium needs
For dwarf nasturtium the mix to buy is peat-free multipurpose compost. Thrives in poor, lean soil — this is one of the few annuals that flowers better without rich compost or fertiliser. Overly fertile soil produces lush, dark green leaves but very few flowers. Good drainage is essential; avoid heavy clay.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 dwarf nasturtium 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?
Dwarf nasturtium is straightforward: an ordinary peat-free multipurpose compost is right. For a big specimen or a pot it will live in for years, mixing in some loam-based John Innes No.2 or No.3 adds weight and holds nutrients longer. Ericaceous compost is not needed unless a plant is specifically a lime-hater.
For the full recipe, pH and drainage detail (US wording), see the dwarf nasturtium soil & potting-mix guide.
Compost for Dwarf nasturtium in the UK — frequently asked questions
What compost should I use for dwarf nasturtium in the UK?
Use peat-free multipurpose compost. Thrives in poor, lean soil — this is one of the few annuals that flowers better without rich compost or fertiliser. Overly fertile soil produces lush, dark green leaves but very few flowers. Good drainage is essential; avoid heavy clay. 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 dwarf nasturtium?
Yes. A good peat-free multipurpose compost is exactly right for dwarf nasturtium. For a large or long-term pot you can mix in some John Innes No.2 or No.3 (loam-based) for extra weight and staying power.
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 dwarf nasturtium perfectly well — they dry a little faster at the surface, so check moisture by feel rather than by the look of the top.
Does dwarf nasturtium 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 dwarf nasturtium need?
Always a pot with drainage holes. Poor to average, well-drained loam or sandy loam, pH 6.0–7.5. 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 dwarf nasturtium care
See the full dwarf nasturtium care guide, its UK watering and UK hardiness.