Coromandel Cacti

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Plant Cultivation

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GROWING LITHOPS : THE LIVING STONES

Coloured and patterned to blend into stony, desert terrain. Lithops are the gemstones of the plant world. So difficult are they to find in the wild that only two species were known in 1900. Dedicated explorers have now discovered a total of 34 species. 14 living in Namibia and 21 in South Africa. (One in both.) Hundreds of named varieties and local forms have also been described.

Lithops is both plural and singular; there is no such animal as a 'Lithop'. Lithops consist of pairs of highly modified leaves that in habitat are usually flush with the level of the ground.

A typical member of the Mesembryanthemum family, the Lithops flower covers the body of the plant when it opens each afternoon for about 10 days in late summer/autumn. Flowers are white or yellow, several are sweetly scented. The low, rounded pebble shape is an adaptation to reduce water loss in a climate of extremely low rainfall. Another adaptation is that the seed capsule opens wide and releases a few seeds every time rain falls, then it closes again, thus spreading the chances of a successful germination. Lithops live to a great age (probably 100 years or more), with some species forming clusters of over 300 heads while others always remain solitary.

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The camouflaged surface has developed because Lithops are sought after as food and water by animals like baboons and bustards. The translucent, patterned window in the top surface, however, has a double function in allowing sunlight to be captured and utilized even when the plant is withdrawn flush with the surface of the soil. In cultivation the worst pests will be root bugs, (unless you keep baboons or bustards). Root bugs require insecticide treatment and thorough washing when repotting. Mice sometimes nibble them also, especially in winter. They like the rarer ones.

Soil should be free-draining and not too high in nutrients. Excess water or excess fertilizer will cause splitting. Light must be bright but be aware that any plant can cook to death on a very hot sunny windowsill. Especially in a small volume dark-coloured pot. Tall or split Lithops have had too much water and/or not enough light. One solution is to carefully cut and peel the older outer leaves off to just above ground level with a sharp knife. You need to reduce the combined influence of (i) too much water available from the too-large older leaves and (ii) too much shade over the young growing leaves from the too-long persisting older leaves. They will look terrible for a short while, but if you don't do it they will look terrible for a long while. Without the surgery the bad cycle will just continue year after year and you will probably become suicidal. Once the new growth appears they will return to normal providing you give them ideal conditions. Multiheading or clustering will not usually begin until after the first flowering. Clusters can be pulled apart, but why bother. It takes many years to grow a decent sized plant. It's like chopping up a fifty year old bonsai to get some cuttings!

Growth cycle of Lithops

Young Lithops up to 15mm diameter need regular light watering all year. Windowsills can be too hot for them. Mature Lithops flower some time between January and June. Give NO water after flowering or after May 31st, whichever comes first. They will wrinkle as water is withdrawn from the outside (visible) leaves and recycled into the new leaves (which may become visible down the fissure as they swell and grow). The old leaves eventually become just a dry, papery husk (around October), and gentle watering can then commence. The husk will be split by the new leaves and it can be removed to prevent shading of the new growth if it has not already blown away. Mouse nibbles and scars will now be gone, the colours are at their brightest, and the Lithops becomes once again a living gemstone. Then water moderately through summer until flowering or the end of May.

Lithops Species

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aucampiae grows fast and large. body to 50mm, cluster to 200mm
bella, 'beautiful'. Only one in both Namibia and South Africa
dinteri, Professor Dinter discovered four species
dorotheae, one of the most striking patterns.
fulviceps, transparent dots. Several distinct forms - red, yellow, milky grey, for example
hookeri, the first discovered, 1811, but not found again until 1918. Very variable
karasmontana, 'Karas Mountains'. Very variable
lesliei, widest range. many forms, easy to grow
naureeniae, first found as recently as 1980, big fissure
otzeniana, large windows, attractive curtains
pseudotruncatella, the earliest to flower, about December or January
ruschiorum, rare, smooth, white pebble. Northernmost of Lithops
salicola, from a salt pan in Orange Free State
vallis-mariae, fine, chalky wrinkles
verruculosa, the only Lithops with an orange flower
villettii, like a white-flowered otzeniana
werneri, smallest, 20mm in cultivation, less in Namibia Also bromfieldii, coleorum, comptonii, erniana, francisci, gesineae, geyeri, glaudinae, gracilidelineata, hallii, helmultii, herrei, julii, localis, marmorata, meyeri, olivacea, optica, schwantesii, viridis plus many minor, named variations. All are worth growing.

THE CACTUS FAMILY

Cacti are the best-known of the forty plant families with succulent species. Over 3000 types, they are all from the Americas, but New Zealand's climate can produce magnificent flowering specimens.

Cacti make their growth in summer and respond to warmth and water, but in winter they rest. From about May to September give no major waterings; but dampen soil every few weeks to prevent root dieback. Modify this according to your winter (the colder the drier).

Explorers and botanists are currently discovering more new cactus species than any other type of cultivated plant. With so many types you may wish to focus on one group in particular.

Examples:
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MAMMILLARIA-Small and attractive, 300 species (plus many varieties) make this the perfect genus to specialise in. 

CEREOIDS are the tall columnar cacti. 100's of types, many of which grow well outdoors in NZ. Bright light if indoors, to prevent etiolation (that is, stretching and narrowing pale growth due to insufficient light). Many have scented nocturnal flowers 

NOTOCACTUS has large flowers and is easy to grow. Of the globular types it grows faster than most. 

Watering Guide

Watch for the growing seasons of your plants but here are some guidelines for the different groups.

Water all year but less in winter:
Adromischus, Aeonium, Agave, Aloe, Cotyledon, Delosperma, Echeveria, Euphorbia, Faucaria, Gasteria, Graptopetalum, Haworthia, Huernia, Kalanchoe, Mestoklema, Pachyphytum, Portulacaria, Sansevieria, Scilla, Sedum, Senecio, Stapelia, Tacitus, Trichodiadema.

Main growth in autumn and winter:
Argyroderma, Aloinopsis, Cheiridopsis, Crassula, Frithia, Massonia, Haemanthus, Othonna, Testudinaria, Titanopsis, Veltheimea.

Pleiospilos:
Keep dry June to September inclusive. Their annual cycle is as for Lithops except the old leaves don't obscure the new. Young plants need regular water.

Conophytum:
Very gentle water in late summer to winter, then dry from mid-spring until about mid-summer. Leaves form a dry skin in spring and early summer; at this time plants may appear dead. In late summer the dead skins split open to reveal shiny new leaves.

Tylecodon:
Keep totally dry from spring until new leaves appear in late summer.

Lump Plants:
Also known as caudiciforms (with distinct caudex) and pachycauls (with thickened stem), often with non-succulent leaves. Cease watering if leaves yellow and fall in autumn or winter. Resume watering when growth resumes. e.g. Pachypodium. Testudinaria grow all year apart from a brief dormancy in mid-summer.

Need only small amounts of water: Argyroderma, Caralluma, Dinteranthus, Fenestraria, Hoodia, Lapidaria, Pseudolithos, Trichocaulon.