I have Acidanthera in a large pot that makes awesome foliage every year.
Pardon my use of vernacular, but WTF do I have to do to get it to actually flower?
Don't think the weather this year will have helped. They need good drainage and sun jen. Have they never flowered? You may need to give them a bit of food, and make sure you change some of the compost each spring. Also, have you taken a look at them to see if they're a bit pot bound?
Full sun, warmth, regular watering but good drainage and a good dollop of slow release fertiliser in spring. Keep them warm to get them started early into leaf in spring and protect from frost..
We've had a cracking summer and autumn here but even so, mine only got into flowering gear in October and some have only flowered in the last week or so. They'll be done for this weekend.
They seem to multiply very willingly so all my pots of them are crammed full. Doesn't seem to affect flowering as much as being cold.
@Fairygirl: Two of the 25-or-so in the pot flowered in November three years ago (the same year I planted them). They're in full sun and well drained.
@obelixx: Getting them to start early sounds a good idea. Mine don't show any growth until late June or July.
I think I'll lift and separate, then re-pot next spring.
As obelixx says - it's the cold they can't cope with. They're not hardy up here so I would have to lift them - couldn't be bothered - or else treat them as annuals, which is what I did when I grew them. I kept them undercover in pots until it was warm enough to plant them out, and they flowered in late summer. I was lucky with the summer weather in those years though - in normal years they'd probably have been later!