Jeff Layman wrote:

I've been growing B. yunnanensis for 3 years from seed. *Still pretty small,
and can't seem to make up its mind whether it's a shrub or weak climber!
Interesting that it needs prolonged hot spells to do anything, but typical
of "inland continental" plants.

It does take a while and it is a very definite climber. A seedling
has a few years of very skinny stems and then suddenly, comparatively
strong thick shoots develop from low down on the plant. Growth then
becomes quite vigorous and 2m or so of growth can be expected each
year. Flowers form in clusters at the tips of axillary shoots and can
appear at any time from June to September. I raised mine from seed in
1999 and first flowers appeared in late 2003. Even when carrying a
lot of bloom, it's not exactly a show-stopper though and must rank as
one of the least showy of the Bauhinias.

But is your B. yunnanensis hardy enough to survive outside? *I still keep
mine in a frost-free (1 - 2°C) greenhouse, and it is pretty much deciduous
even under those conditions.

Yes my plant has been growing outside since its second year and with
the exception of this winter, is more or less evergreen. Here,
temperatures may fall to minus 2C for an hour or so a couple of times
each winter and there may also be a few short lived drops to minus 1C,
but it is more or less frost free for most of the time.