UK compost
What compost for optical plant in the UK?
Lithops optica
More about optical plant in the UK
Which compost optical plant needs
For optical plant the mix to buy is peat-free multipurpose compost cut roughly half-and-half with horticultural grit or perlite. Use 65–70% inorganic material (fine pumice, coarse perlite, quartz grit) blended with a small amount of succulent compost for minimal nutrient provision. Neutral to slightly alkaline pH (6.5–7.5), reflecting its coastal limestone and quartz habitat. Terracotta pots and a gravel top-dressing are strongly recommended.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 optical plant 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?
Optical Plant 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 optical plant soil & potting-mix guide.
Compost for Optical Plant in the UK — frequently asked questions
What compost should I use for optical plant in the UK?
Use peat-free multipurpose compost cut roughly half-and-half with horticultural grit or perlite. Use 65–70% inorganic material (fine pumice, coarse perlite, quartz grit) blended with a small amount of succulent compost for minimal nutrient provision. Neutral to slightly alkaline pH (6.5–7.5), reflecting its coastal limestone and quartz habitat. Terracotta pots and a gravel top-dressing are strongly recommended. 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 optical plant?
Not on its own — multipurpose compost holds too much water for optical plant 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 optical plant perfectly well — they dry a little faster at the surface, so check moisture by feel rather than by the look of the top.
Does optical plant need grit or perlite added?
Yes — optical plant 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 optical plant need?
Always a pot with drainage holes. Very lean, fast-draining mineral 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 optical plant care
See the full optical plant care guide, its UK watering and UK hardiness.