UK compost
What compost for carrot-leaved pelargonium in the UK?
Pelargonium rapaceum
More about carrot-leaved pelargonium in the UK
Which compost carrot-leaved pelargonium needs
For carrot-leaved pelargonium the mix to buy is peat-free multipurpose compost cut roughly half-and-half with horticultural grit or perlite. Use a mix of 40% loam or peat-free compost, 40% coarse horticultural grit, and 20% perlite. Plant the tuber with its neck just at the surface to avoid moisture accumulation around the vulnerable crown.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 carrot-leaved pelargonium 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?
Carrot-leaved Pelargonium 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 carrot-leaved pelargonium soil & potting-mix guide.
Compost for Carrot-leaved Pelargonium in the UK — frequently asked questions
What compost should I use for carrot-leaved pelargonium in the UK?
Use peat-free multipurpose compost cut roughly half-and-half with horticultural grit or perlite. Use a mix of 40% loam or peat-free compost, 40% coarse horticultural grit, and 20% perlite. Plant the tuber with its neck just at the surface to avoid moisture accumulation around the vulnerable crown. 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 carrot-leaved pelargonium?
Not on its own — multipurpose compost holds too much water for carrot-leaved pelargonium 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 carrot-leaved pelargonium perfectly well — they dry a little faster at the surface, so check moisture by feel rather than by the look of the top.
Does carrot-leaved pelargonium need grit or perlite added?
Yes — carrot-leaved pelargonium 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 carrot-leaved pelargonium need?
Always a pot with drainage holes. Extremely free-draining, sandy-gritty 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 carrot-leaved pelargonium care
See the full carrot-leaved pelargonium care guide, its UK watering and UK hardiness.