UK compost
What compost for japanese black pine 'kotobuki' in the UK?
Pinus thunbergii 'Kotobuki'
More about japanese black pine 'kotobuki' in the UK
Which compost japanese black pine 'kotobuki' needs
For japanese black pine 'kotobuki' the mix to buy is peat-free multipurpose compost cut roughly half-and-half with horticultural grit or perlite. Use a gritty, open mix such as akadama with a high proportion of pumice and lava, or coarse grit-based substrate. Pines need oxygen at the roots and a lean medium; rich, water-retentive soil promotes weak growth and root rot.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 japanese black pine 'kotobuki' 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?
Japanese Black Pine 'Kotobuki' 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 japanese black pine 'kotobuki' soil & potting-mix guide.
Compost for Japanese Black Pine 'Kotobuki' in the UK — frequently asked questions
What compost should I use for japanese black pine 'kotobuki' in the UK?
Use peat-free multipurpose compost cut roughly half-and-half with horticultural grit or perlite. Use a gritty, open mix such as akadama with a high proportion of pumice and lava, or coarse grit-based substrate. Pines need oxygen at the roots and a lean medium; rich, water-retentive soil promotes weak growth and root rot. 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 japanese black pine 'kotobuki'?
Not on its own — multipurpose compost holds too much water for japanese black pine 'kotobuki' 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 japanese black pine 'kotobuki' perfectly well — they dry a little faster at the surface, so check moisture by feel rather than by the look of the top.
Does japanese black pine 'kotobuki' need grit or perlite added?
Yes — japanese black pine 'kotobuki' 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 japanese black pine 'kotobuki' need?
Always a pot with drainage holes. Very free-draining, lean inorganic bonsai 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 japanese black pine 'kotobuki' care
See the full japanese black pine 'kotobuki' care guide, its UK watering and UK hardiness.