In article ,
Martin Brown wrote:
On 06/11/2014 08:51, stuart noble wrote:

In an unheated frost free place they can keep for the winter months with
no soil on the roots and go dormant. The fat stems hold a fair amount of
water and it is in their nature to go dormant for winter.

This was part of what the argument was about on Gardenweb. Is the
dormancy natural or forced on the plant in colder climates?

I think it is natural. You just have to get the right combination of low
humidity and frost free cold for them to be happy. That is harder to do
in the UK than it sounds and some may be lost to damp rots.

Some of the hardest plants to grow in the UK are cacti that naturally
grow in places at high altitude with a continental winter. In their
natural habitat the winters are very cold but with essentially zero
humidity until the thaw when they start to grow again. eg Sclerocactus

http://en.wikipedia.org/wiki/Sclerocactus

They are inclined to rot in the UK winter climate.

There are a lot of other plants that have the same characteristic
to a greater or lesser degree - many Cyclamen among them. And
Passiflora incarnata, which grows over most of the south-eastern
USA and up into Canada, but is very iffy here. Its roots normally
survive in the very dry soil under the frozen ground in the cold
winter areas.



Regards,
Nick Maclaren.