"Janet Galpin and Oliver Patterson" wrote
I have a couple of questions about I. unguicularis

I have a bluish one, maybe 'Walter Butt',
snip
This year a big let-down. I haven't yet had a single flower and I
wondered if anyone could guess why it might be. I assume it must be to
do with temperature at vital times but whether last summer's
temperatures or the winter's temperatures I haven't a clue.

I believe it's to do with getting baked enough during the previous summer.
Hot dry summers usually bring good flush of flowers the following late
winter/spring.

Secondly, I've rooted an off-cut from it and I'm wondering where to
plant it. I've run out of south-facing wall and I'm wondering whether
it's unlikely to flower (especially judging by this winter's
performance) in a south facing sheltered border among shrubs etc. Any
experience of getting it to flower in less than ideal situations?

Mine hardly ever flowered until I read in one of Gertrude Jekyll's books
how she found hers did best in very nearly rubble at the foot of a wall.
However, my neighbour has one in the open which does well, but it needs to
be somewhere with poorish soil and where it can get all the sun going. They
cut all the foliage right back after flowering which also seems to help.

Sue