CULTIVATION

Sceletium is a small genus of low-growing succulent shrubs in the ice plant family (Aizoaceae) endemic to the Karoo areas of Western, Eastern and Northern Cape Provinces in South Africa. The succulent leaves grow in pairs and eventually die away leaving persistent leaf vein skeletons clothing the lower stems, which protect the plants from adverse environmental conditions. The small flowers vary in colour from white to yellow and occasionally pale orange or pink.

Most of the Sceletium species are mostly unknown in cultivation and endangered in habitat. Plant gatherers in South Africa have observed that wild populations of Sceletium tortuosum are becoming increasingly scarce, possibly due to over-collection. Protection through cultivation is encouraged.

Sceletium is easily grown, and seeds are sprouted much the same as any common cacti. Mature plants also root easily from cuttings. Sceletium can become weedy if over-watered and overfed. Some species are tolerant of mild frost, but it’s best not to bring them outdoors until the last frost has passed.

If growing in a pot, the soil should be allowed to dry out between watering. Obviously the size of the pot is a variable where this is concerned, but as long as the plant body remains firm-looking with no signs of wrinkling, then resist the temptation to over-water. Make this judgment on cooler days; during very hot and sunny periods, most plants will have a tendency to wrinkle especially if they are in a greenhouse. If in doubt, don’t water.

Watering Sceletium is something of a balancing act… too little and the plants become stunted… too much and they rot or, at best, they start making new bodies at the wrong time of year (if this happens stop watering until the first body has been consumed by the new). After a year or two you will get to know how the plants behave in your particular situation.

So water sparingly until shoot and root growth is well established. Then increase watering and apply a well-balanced liquid feed periodically. Good light is essential so that plants produce strong, sturdy growth. Ideally maintain a minimum temperature of 16ºC or 60ºF, although plants will tolerate cooler conditions. Any general purpose compost with some added grit to help drainage is suitable – or any of the propriety cactus composts is ideal. An occasional feed as for houseplants is permissible but don’t overdo it – Sceletium plants require little in the way of nutrients.

The planting site should be open and sunny and the soil can be enriched with general cactus soil or compost, as was used when they were in a pot. Space the Sceletium plants some distance apart because they creep along the ground, much like plants that propagate through rhizomes, and, when cared for properly, they can take up a lot of ground space in a short amount of time.

After the first frost comes, lift the rhizomes and move them to a frost-free glasshouse or shed. Ensure plants are properly labelled to keep track of genetics.  Pack the roots in pots, covered with compost or bark, and keep them just moist throughout the winter.

Take great care with unwrapping the Kanna – new shoots at this stage are extremely fragile, and a shoot broken off represents a lost flowering shoot. Sceletium has a lot of water content and in travelling they can become dehydrated and less pliable.

The seedlings should be immediately potted up, irrespective of the time of year. Use any general purpose cactus soil, and place the pots in a light, airy, frost-free place. A cool greenhouse with heat only when frost threatens is ideal. Keep the compost slightly moist (not dry, not over-wet), until the growing season starts.

If immediate potting is impractical, the seedlings should be covered in damp peat. Sceletium seedlings do not normally enter a totally dormant stage, and if they are thoroughly dried out, then some will be lost. (This is perhaps one reason why Kanna plants are not often sold in garden centres – they do not appreciate being kept for long periods in a handful of dry sawdust in pre-packs – many are then lost, leading to complaints).

If the Sceletium plants are intended for indoor cultivation, then they may be potted up immediately and grown on under heat.

As with many rhizomatous plants, not every Kanna seedling will grow (Sceletium growers are happy with an 80% success rate), although some will throw up 2 or 3 shoots.

In the spring, newly emerging shoots should be sprayed for aphids, though aphids are not often a problem with grown plants.

Young plants should be protected from slugs and snails which ignore the open leaves but have a preference for the newly unrolling leaves. A single nibble at this stage by a slug will cause a disfiguring row of holes as the leaf unfurls that will remain with the plant for several months. Older plants are not often troubled by slugs and snails.

Red Spider Mite can occasionally infest indoor Sceletium plants. The symptoms are dry-looking leaves which turn uniformly brown. When examined closely on the underside, such leaves show traces of a white powder (which is the dried egg-cases) particularly near the central leaf rib, and myriads of extremely tiny creatures all running around. You really need a magnifying glass to see them. To answer a common query, Red Spider Mites are not often red in colour.

Red Spider Mite is immune to most, if not all, proprietary preparations available to the amateur – although neem oil or pyrethrin-containing products can often control them successfully. Soap-based insecticides combined with a powerful spray can dislodge and/or suffocate them, and minimize the problem to an acceptable level too. 

Sceletium plant virus disease is more widespread than is commonly appreciated. It is initially recognized by pale coloured spots and streaks in leaves, and by distorted or crinkly leaves. Later, badly-affected plants show dead rust-coloured streaks in the leaves, throughout the plant, and the growth is badly stunted. The plant may still flower, but the flowers may have a distorted shape with white patches. Little is known about Sceletium plant virus – some plants are badly affected and may die of their own accord, or remain badly stunted, but other plants show only a mild infection of one or two leaves and seem to be able to recover. There is no known cure for virus- diseased plants, and plants that are obviously diseased should be dug up and destroyed.