Orchid Composts and Containers
Compost forwas formerly made from the root fibres of osmunda , with sphagnum moss and leaf-mould. However, the formulations today are quite different, often organic and chemical-free; some contain pine bark chippings or plastic shavings.
The simplest compost is made by mixing two parts of sphagnum moss peat, one part of coarse horticultural sand or fine gravel, and one part of perlite.
A more complex compost is made from ten parts of medium-grade pine bark, five parts of fine-grade pine bark, one-and-a-half parts of horticultural perlag and one-quarter part of crumbled charcoal.
With both types of compost, bring the pH value up to 5.5-6.0 by adding lime. For slipper orchids, raise the pH to 6.5.
Orchids can be grown in ordinary pots, but these must have a good layer of crocks at the bottom to allow for rapid drainage.
Special orchid pots or pans —obtainable from some garden centres and specialist nurseries —are perforated around the sides as well as the bottom, so need no drainage material.
Wooden baskets are more suitable for pendent plants. When planted, they are hung up in the greenhouse using wires or slender chains, allowing the stems to droop downwards.
Alternatively, pendentorchids can be grown on sections of rough tree bark or cork. Sections of tree stems — if available — are also ideal. Bind the orchid roots to the raft of bark using nylon fishing line or fine plastic-covered wire.
To prevent the orchid drying out unduly until new roots develop and get a firm hold on the bark, pack some compost under the roots before you tie them in. Hang the bark and attached orchid from the greenhouse framework.