UK compost
What compost for alpine balsam in the UK?
Erinus alpinus
More about alpine balsam in the UK
Which compost alpine balsam needs
For alpine balsam the mix to buy is peat-free ericaceous (lime-free) compost. Naturally grows in limestone crevices. Prefers a lean, gritty mix with pH 6.5–8.0. Add crushed limestone or pea gravel to a loam base. Rich, acidic soils produce large floppy leaves and few flowers.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 alpine balsam 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?
Alpine Balsam 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 alpine balsam soil & potting-mix guide.
Compost for Alpine Balsam in the UK — frequently asked questions
What compost should I use for alpine balsam in the UK?
Use peat-free ericaceous (lime-free) compost. Naturally grows in limestone crevices. Prefers a lean, gritty mix with pH 6.5–8.0. Add crushed limestone or pea gravel to a loam base. Rich, acidic soils produce large floppy leaves and few flowers. 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 alpine balsam?
No — alpine balsam 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 alpine balsam perfectly well — they dry a little faster at the surface, so check moisture by feel rather than by the look of the top.
Does alpine balsam 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 alpine balsam need?
Always a pot with drainage holes. Gritty, well-drained alkaline or neutral soil. 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 alpine balsam care
See the full alpine balsam care guide, its UK watering and UK hardiness.