UK compost
What compost for petunia 'supertunia royal velvet' in the UK?
Petunia × atkinsiana 'Supertunia Royal Velvet'
More about petunia 'supertunia royal velvet' in the UK
Which compost petunia 'supertunia royal velvet' needs
For petunia 'supertunia royal velvet' the mix to buy is peat-free ericaceous (lime-free) compost. Use fertile, free-draining multipurpose compost in containers or improved garden soil, ideally pH 5.5-6.5. Sharp drainage prevents root rot; amend heavy soils with organic matter and grit.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 petunia 'supertunia royal velvet' 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?
Petunia 'Supertunia Royal Velvet' 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 petunia 'supertunia royal velvet' soil & potting-mix guide.
Compost for Petunia 'Supertunia Royal Velvet' in the UK — frequently asked questions
What compost should I use for petunia 'supertunia royal velvet' in the UK?
Use peat-free ericaceous (lime-free) compost. Use fertile, free-draining multipurpose compost in containers or improved garden soil, ideally pH 5.5-6.5. Sharp drainage prevents root rot; amend heavy soils with organic matter and grit. 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 petunia 'supertunia royal velvet'?
No — petunia 'supertunia royal velvet' 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 petunia 'supertunia royal velvet' perfectly well — they dry a little faster at the surface, so check moisture by feel rather than by the look of the top.
Does petunia 'supertunia royal velvet' 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 petunia 'supertunia royal velvet' need?
Always a pot with drainage holes. Rich, well-drained, slightly acidic potting mix or loam. 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 petunia 'supertunia royal velvet' care
See the full petunia 'supertunia royal velvet' care guide, its UK watering and UK hardiness.