UK compost
What compost for alisma plantago-aquatica in the UK?
Alisma plantago-aquatica
More about alisma plantago-aquatica in the UK
Which compost alisma plantago-aquatica needs
For alisma plantago-aquatica the mix to buy is peat-free multipurpose compost. Plant in fertile heavy loam or pond mud in an aquatic basket. It accepts most waterlogged soils provided they stay wet and reasonably rich.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 alisma plantago-aquatica 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?
Alisma plantago-aquatica 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 alisma plantago-aquatica soil & potting-mix guide.
Compost for Alisma plantago-aquatica in the UK — frequently asked questions
What compost should I use for alisma plantago-aquatica in the UK?
Use peat-free multipurpose compost. Plant in fertile heavy loam or pond mud in an aquatic basket. It accepts most waterlogged soils provided they stay wet and reasonably rich. 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 alisma plantago-aquatica?
Yes. A good peat-free multipurpose compost is exactly right for alisma plantago-aquatica. 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 alisma plantago-aquatica perfectly well — they dry a little faster at the surface, so check moisture by feel rather than by the look of the top.
Does alisma plantago-aquatica 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 alisma plantago-aquatica need?
Always a pot with drainage holes. Heavy wet loam or mud. 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 alisma plantago-aquatica care
See the full alisma plantago-aquatica care guide, its UK watering and UK hardiness.