British Cactus and Succulent Society

Highlands & Islands Branch

Plant Management








If a cactus plant is grown in plenty of light and warmth, in a suitable compost, and with proper attention to watering - the reward should be good flowering. We cannot imitate the intensity of light they enjoy in their native habitats - mainly because we are so far north, but longer summer days do compensate. Warmth is generally easier to maintain. Rebutia will tolerate down to about -5C but some others need to be kept at not less than 10C. How can these conditions be achieved in practice.

Our weather conditions make growing cacti and succulents outdoors, all year round, a very doubtful proposition. There is a report that a lady did this in Alexandria (Dunbartonshire), but this has not been proved. Most growers do put plants out during the summer which probably does them a lot of good. Some growers make use of garden frames which allow cover if the weather deteriorates, or even if there is prolonged sunshine and little wind. In most cases plants are grown in a greenhouse or conservatory. Small collections have been grown on a window-sill, and won prizes.

The first environmental condition of greenhouse culture is proper lighting and the second is almost certainly good ventilation. It is said the latter is best met by the type of greenhouse used for alpines. These usually open all along the sides, and even the roof. In the author's view the superstructure of such greenhouses is substantial and cuts the light down, quite a lot. Whether there is an advantage in having special glazing in a normal greenhouse is a moot point.

Branch committee members were asked about heating at the same time as being asked about compost.

In all cases heating was provided by thermostatically-controlled electric heating, at a setting of about 48-50F. On one occasion this was boosted by gas heating. Particularly sensitive, or valuable plants were taken indoors for the winter. A centrally-heated conservatory avoids such problems of course. None favoured oil-heating. Whether this was because of the problem of water-vapour, or perhaps the danger of mal-function when plants have been known to be blackened by soot by morning. One member who grows mountain cacti in a cold greenhouse, and succulents indoors, provided no heating, except for a large candle (in an 8X6 greenhouse) when temperature fell below -5C he would put two layers of newspapers over the plants by about 16.00 hours. Some Rebutia, it is said, are under snow in the Andes, for six months of the year and the newspapers are intended to simulate snow cover. When temperature fell below about -12C a large 75mm candle was used, and that seems to work.

'Damping down' was standard practice for other plants at one time. For some plants, such as orchids it is highly desirable, if not essential - but not cacti. The argument in favour of an occasional fine spray is that some cacti grow in areas where there is a wide swing in temperature which causes heavy dews. It seems that cactus spines are quite adept at capturing such moisture.

Last, but not least -
Keep in mind there are pots, and pots, and pots, and that a fourth type of pot which appeared recently on the scene is ceramic and often highly coloured. It is claimed to be de rigeur and is said to be a colourful difference between British and USA shows.

Third in that row of pots is the ubiquitious plastic pot which now dominates our gardening activities. It is far from ideal because it is too thin, heats up in sunshine too much baking the roots of plants which would not happen so much in the wild, and it cannot breathe. Also, it cracks readily especially when exposed to sunlight.

Second in the list are modern clay pots but first in the list are old Victorian or Edwardian pots, many of which were hand-made.They can often be obtained at country sales, and usually show an uneven surface on the inside, and even outside on some. The advantage of a clay pot is that it can breathe. This lets air into the root system similar to natural conditions. One disadvantage is that when they dry out roots may cling to the sides of the pot to take up the moisture in the air which percolates through the pot wall. Clay pots are probably at their best when plunged. The other essential aspects of a plants' environment are compost and watering.

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