Cacti and succulents generally enjoy as much sunshine as we can give them. Only shade a plant if it turns too reddish or fades to a paler green. In winter, our short days offer barely enough light, so the plants should not be shaded at all. Turn window-sill plants round occasionally to stop them becoming lop-sided. Also avoid extreme cold or a damp clammy atmosphere in winter. Some kinds can survive slight frost if completely dry; others may need a higher temperature. Most kinds can be overwintered at about 5°C or 40 to 45°F.
Most of the plants we sell are grown by our members. Cactus and succulent plants offered for sale have generally been re-potted recently and will not normally need new pots or compost for a year or so. If the plant becomes squashed against the side of the pot, or grows well one year but not the next, it needs re-potting. Plastic or other nonporous pots are best - choose a size which is around 1 inch wider than the old pot for small plants, and perhaps 2-3 inches wider for large plants. For compost, use John Innes no.1 potting compost (or no.2 for bigger plants), or a peat-based compost such as Arthur Bower's, mixed with at least half as much again of fine grit or coarse sand, not builders' sand. A top dressing of grit shows the plants off well, retains moisture in the soil and also helps prevent moisture remaining around the neck of the plant which can cause rot. When repotting a plant, if it is spiny, wrap it in several layers of newspaper to protect the spines (and yourself!). If the plant is difficult to dislodge from its old pot, insert a stake through the drainage holes to loosen the roots, or if necessary, gently break off the old pot.
Most cacti and succulents like a little fertiliser. Don't use vegetable fertilisers, which have too much nitrogen and encourage too lush growth and few flowers. We suggest "Chempak no.8" or a tomato fertiliser, but anything which contains trace elements and is low in nitrogen should be suitable. "Miracid" is also recommended since most cacti prefer slightly acid soil. With all feeds, use half the recommended dose every other watering, but not at all during winter.
Highly succulent plants such as Lithops ("Living Stones") and Conophytum have special requirements: they need very bright conditions, and it is very important to withhold water during their resting season in winter and early spring. You should stop watering Lithops in late October and Conophytum in January. The old plant bodies will gradually shrivel during the winter, and new ones will develop inside. When the old leaves have dried to a papery skin and new growth is visible beneath you can start to water them again; this is usually from mid-April to early June, depending on the variety. These plants are sensitive to over-watering, and should not be given fertiliser at all, or they will become very bloated and will probably split.
Epiphyllums, Christmas and Easter cacti and Rhipsalis are unusual cacti which grow in forests and like partial shade. They prefer rain-water to tap-water if possible, enjoy fertiliser, and do not like their roots to dry out completely, even in winter.
One thing to watch out for is pests. Red spider can be a problem if the plants are kept too dry, while the presence of white wooly patches indicates mealy bug. Scale insect can also be a problem. Sciara fly (the small black flies which often fly around house plants) lay their eggs in fresh compost and their larvae can devastate young seedlings and cuttings. Keep a close eye on your plants and use a systemic or contact insecticide to deal with them. If you do spot a problem, move infected plants away from healthy ones.
We have produced our own booklet of cultural hints and this is available at shows and meetings for 25p. The booklet includes hints on propagating from cuttings and growing new plants from seeds.
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District Branch.