About the genus
The French collector Frédéric Schlumberger was honoured by Charles Lemaire in 1858 by the use of his name for this genus, which grows on a section of the south-eastern seaboard of Brazil and inland into hilly and forested terrain. Plants grow on either rock surfaces or epiphytically on the trunks of trees.
The hybridisation of two species (which started almost as soon as they reached Europe) is largely responsible for the multitude of different colours now available in supermarkets and garden centres, particularly around Christmas or Easter time.
The so-called Christmas cacti can flower at any time from September through to the end of April and were developed by the crossing of S. truncata and S. russelliana. The plant now known as S. gaertneri produces bright scarlet flowers between March and May and is commonly referred to as the Easter cactus.
A few other epiphytic cacti such as S. rosea have also reached Schlumbergera after several name changes. These, while not so ‘brash’, have their own more subtle qualities.
How to grow them
The simplest propagation technique is taking stem segment cuttings. Preferably these should include a segment which has branched as these tend to root more easily. Aerial roots are often produced which should be selected if seen. Bearing in mind their preferred habitat in Brazil, the addition of a part of composted bark to one of John Innes and one of grit produces good results.
At the cutting stage, focus should be on the development of roots. Ideally a propagator and reliable artificial light source should be utilised to maintain moisture, warmth and light levels until it is clear, by the healthy nature of growing segments, that roots have established. If you have enough material, it is worth trying several cuttings at the same time and, if you are short of space, two or three may be accommodated in a single pot.
Water approximately once a week when the compost is dry. Excessive amounts of water will lead to stem rot. During the growing season use a little dilute fertiliser with each watering. There is no need for a special formulation. I use a general houseplant fertiliser sold in a small bottle.
Most Schlumbergera will produce flowers when grown in a light position, preferably out of direct sunlight as reddening of the foliage will otherwise result. A warm north-facing windowsill is ideal. Yellow-flowered Schlumbergera are highly-prized and, given at least 20°C, should produce two flushes of flowers throughout the year. If the temperature is lower then the flowers produced will tend to be paler.
There is a huge range of colours available in today’s cultivars. Deep red flowers are often accompanied by a startling white floral tube. The red colour also influences other cultivars which bear strawberry-pink flowers. White flowers are also becoming more common on Christmas cacti and again the temperature-sensitive nature of this colour may well contain shades of pink, rather than pure white if an adequate temperature is not maintained.
If the sunlight is too strong or adequate heat is not available, the smaller-flowered Schlumbergera like S. rosea may not flower at all.
Text and photos by Peter Berresford.
No part of this article may be reproduced without permission. Copyright BCSS and the Author 2021