Nick Maclaren wrote ( Aloe ciliata?):

Mine (in the conservatory) doesn't flower at all well - I tend to
ignore it, rather, though it is in a border that goes down to the
subsoil and it grows very happily. Any ideas?

It tends to respond well to good growing conditions in summer with lots
of sun, plenty of water and regular feeding. Being an Aloe, folks tend
to consider it as a succulent that prefers fairly austere treatment.
However, its barely succulent leaves and lax growth indicate that it
needs rather better. Mine is kept in a very large container close to
the house wall, where it benefits from 'rain-shadow' in winter and
remains completely frost free. In summer it gets baked for most of the
day and the stems can grow as much as 2m. given a little encouragement.
Inflorescences are borne at the stem tips, usually in late winter/early
spring and it is important that the shoots remain undamaged.

The coldest so far was about -4, and just enough to kill the leaves
of Erythina crista-galli.

I've not seen anything below 1C. in the coldest part of the garden so
far. I don't have crista-galli although I find it an exceptionally
handsome shrub - especially the compact form. I have E. indica, which
is still in leaf - nowhere near as attractive and significantly more
tender. It is only a couple of years old and has yet to flower. I was
certain that last winter would see it off, but it barely suffered any
die-back and has grown quite well this year. As to your Albizia, if
severe frosts hold off for another few weeks the shoot tips should have
hardened enough to take the usual February onslaught.