Nick wrote:

My guess is that it shouldn't be much trouble, provided that your
conservatory stays comfortably above freezing. As I understand it,
Mandevilla laxa is nearly as hardy as Passiflora caerula, but is
rather more sensitive to waterlogging in winter,

Against a sunny wall in the south, it acquits itself quite well out of
doors once established. It hates a windy spot though and regardless
of summer warmth, makes little growth in such positions.

... and Mandevilla
boliviensis is happy as long as not waterlogged and above about
2 Celcius.

About right, although some of the hybrids prefer it a bit warmer to
around 5C. That is not to say they wont survive at lower
temperatures, but they are more susceptible to damp-induced grey mould
and are less eager to 'wake up' in spring. Keeping them nearly dry at
root helps and plenty of freely moving air will deter the mould.

The very glamorous 'Alice du Pont' will easily overwinter here outside
and even hold on to many of its leaves. However, it almost always
dies away after making a feeble amount of growth in late spring.

That's the problem with growing such plants in a mild maritime
climate. Getting them through winter is less of a problem than
arranging for a continental-type heat surge in spring to really get
them going again in spring.


Dave Poole
Torquay, Coastal South Devon UK
Winter min -2°C. Summer max 34°C.
Growing season: March - November