UK compost
What compost for begonia grandis subsp. evansiana in the UK?
Begonia grandis subsp. evansiana
More about begonia grandis subsp. evansiana in the UK
Which compost begonia grandis subsp. evansiana needs
For begonia grandis subsp. evansiana the mix to buy is peat-free multipurpose compost cut roughly half-and-half with horticultural grit or perlite. Prefers a moist but free-draining loamy or sandy soil enriched with organic matter. Good drainage is essential for the tubers to overwinter; heavy, waterlogged clay encourages rot. A leafy mulch helps retain moisture and protects the crown in cold zones.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 begonia grandis subsp. evansiana 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?
Begonia grandis subsp. evansiana 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 begonia grandis subsp. evansiana soil & potting-mix guide.
Compost for Begonia grandis subsp. evansiana in the UK — frequently asked questions
What compost should I use for begonia grandis subsp. evansiana in the UK?
Use peat-free multipurpose compost cut roughly half-and-half with horticultural grit or perlite. Prefers a moist but free-draining loamy or sandy soil enriched with organic matter. Good drainage is essential for the tubers to overwinter; heavy, waterlogged clay encourages rot. A leafy mulch helps retain moisture and protects the crown in cold zones. 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 begonia grandis subsp. evansiana?
Not on its own — multipurpose compost holds too much water for begonia grandis subsp. evansiana 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 begonia grandis subsp. evansiana perfectly well — they dry a little faster at the surface, so check moisture by feel rather than by the look of the top.
Does begonia grandis subsp. evansiana need grit or perlite added?
Yes — begonia grandis subsp. evansiana 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 begonia grandis subsp. evansiana need?
Always a pot with drainage holes. Fertile, humus-rich, well-drained, neutral to acid 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 begonia grandis subsp. evansiana care
See the full begonia grandis subsp. evansiana care guide, its UK watering and UK hardiness.