Clematis Florida Sieboldii

I have had a couple of these plants in a large pot and they have not produced a flower for a couple of years; however, in the last 2 weeks suddenly around 10 flowers have appeared.

Why should this be so?

Are they young plants?  How long have they been in the pot and have they been re-potted at all? How do you prune and feed them?

They usually have a long flowering period - as we've had such a cool and dsmal summer maybe they're late because they're responding to the bit of sunshine and warmth we had in the autumn.

I'd prune them hard in March and give them a dollop of rose fertiliser - or if they've not been repotted in the last couple of years I'd do that and give them some new compost to get their roots into.  Clematis are greedy and need lots of nourishment. 

I think these are lovely. Are they hardy enough for garden use?

All clematis require a lot of food to produce decent flowers so, if they're in pots, you need to make sure they get a liquid feed every week through the growing and flowering season.   This summer, having been so cool and damp and grey ahs not been the best for the large flowered wlematis to perform.

My clemati ssupplier reckons Florida Sieboldii is hardy to -10C but I had one killed off by less than that.  In a pot it will be even more vulnerable so should be stored in a sheltered spot and have the pot, but not the plant, wrapped in bubble wrap to give extra protection to the roots.

Lovely as it is, with all the hardy ones available that's probably not the one for me.

Thanks

My supplier lsts most of his clematis with their degree of hardiness and has many good to -25C.   http://www.clematis.be/startfr.html

It's in French, or Flemish, but you can look up clems by name and check their hardiness.  Most have a photo but, if not, you can try here for more info - http://www.clematis.hull.ac.uk/ 

Thank you. I'll have a look

Thanks for all the comments. they've been in the pot 2-4 years (2 plants put in at separate times.) The first one suffered clematis wilt about 3 years ago during August but it came again. I fed them earlier in the year. I'll cut them back hard in spring.

If growing florida sieboldiana or it's sister florida flore pleno, it is best to bring the pot in over winter, greenhouse, garage, shed, don't allow the plant to get waterlogged whilst dormant.

Just chop off all the top growth to about 6 inches, then start to water and feed again in March or April when new growth appears.

I've just bought 3 of these as plugs, guess I should keep them indoors for a few weeks - at least!

Irene, I have my 3 in the greenhouse outdoors, they are fine