As the April meeting was delayed due to the Sheffield half marathon as well as Easter we were unable to host our planned speaker Phil Seaton. A forum was therefore held instead.
A number of Cattleyas had been brought in which were in various states of distress. These were the worst ones of a larger number that had come from Chantelle’s closing down sale. They included some small growing plants as well as several larger specimens and of course several in between these sizes. All were showing signs of shrivelling in the canes, which looked worse in the smaller plants. The smallest one was in a coconut husk which under damper circumstances would be OK, but here was possibly making the situation worse as the plant wasn’t binding to the shell.
The plants are being grown in a number of locations within the house to get the benefits of humidity in the bathroom and kitchen as well as better light in room window sills as well as a conservatory.
Watering is generally the issue with shrivelling plants, and once this has happened to the older canes it is unlikely to be reversed. Old cane’s main purpose is to store liquid and nutrients to feed the growing end of the plant when nature stops supplying the basic requirements of water/rain – obviously in species, but carries on into the hybrid genes. Shrivelling is the first obvious sign that something is wrong with our carefully managed environment.
Within Cattleyas there is natural variety within the species and the way they grow. Some are intermediate, and some are warm growing. Some have a natural dry period, with little humidity. All like bright light, mainly dappled, and sometimes they will grow in full sun. However, they all like good drainage, and this is often the starting problem/point with Chantelle’s plants.
These plants have started life in Taiwan, where they are in more of a natural habitat/environment although it is Asia rather than South America. They are grown under a bit of shade cloth, and watered daily in quite warm conditions (in Taiwan this is more towards sea level rather than in the mountains). As small plants they are packed into moss balls, and their roots quickly grow through this, and into the humid air. At a slightly bigger size the small plants are put into open pots with just a bit more moss, and compressed into the moss. Again roots grow out and they then cling to the pots where they can be difficult to dislodge. After another year or so they are heading towards flowering, and at this point, and in perfect conditions they are shipped to Europe (and elsewhere), where they will be sold as flowering plants, and usually go on to produce high quality specimens if handled correctly.
Most growers agree that the first thing that you have to do is to remove the moss from the roots, even if it is coming into flower – more experienced growers may leave it until after flowering, and on an odd occasion some (such as I) may leave it longer. Again this isn’t advised for the less experienced. The reason for this is that we can’t reproduce the Taiwan environment of heat, light and therefore evaporation from the moss. The result is that over a short period of time the moss retains water, and this causes the roots to rot. As this rot starts, the roots stop supplying nutrients to the plants, and they start to draw on their resources from the older canes. At this point you may feel the need to water more often, and the situation can become compounded, and the situation becomes serious. If not resolved then the compost bin will become the final resting place. As we have usually paid good money for a quality plant then this goes against the grain. The remedy is fairly simple.
Repotting is a straightforward bit of work, especially for Cattleyas, and at this time of year. As the days are now longer and brighter the plants are growing, and should easily produce new roots. If possible, knock out the plant from the old pot, which may take some effort, with torn roots etc. Remove all the old moss, which in some cases is dull and time consuming work. When removed, select a pot that is the same size or a bit larger in width, not necessarily in depth. For small plants and small pots, use a relatively fine bark, and for large plants use larger bark as the roots will be that much larger and need more room to penetrate and latch onto something for stability. Clear pots aren’t necessary, but can be useful to check on progress (putting these into dark pots will prevent algae/moss growing, whilst allowing for an occasional check up).
Put the plant into the new/old pot, holding it to put the base of the most recent full growth just below the top of the pot level, and put handfuls of compost around the roots. Tap the pot and bang it around a bit to ensure all the gaps are filled, and then smooth off.
Water the plant well, and then put it into a bright and warm location, where it should soon settle down and grow new roots. At this time of year I would feed at almost every watering with half strength fertiliser, easing off a bit in autumn.
Don’t be put off by any of this, and remember that often you only learn by your mistakes – I’ve made plenty! Cattleyas are easy to grow when you know how, and the flowers are even more rewarding than e.g. Phalaenopsis.
Simples! Good luck, John Garner