I have several new clematis which are in group 3. Some have grown to the top of the trellis and are wending their way across the top. I'm trying to understand about how they should be pruned. The Alionushkas have had 3 or 4 flowers on them and I have 3 flammulas which are only about 18 inches high and are just showing signs of a few flower buds. What would your advice be with these please? As I understand, you prune in March to above the first pair of strong buds. Does this mean that they have to make all their growth every year? I know that they flower on new wood so will they never be any bigger than they are this year? I've no experience with these and hope that my question isn't too garbled!
You're right that group 3 clematis flower on new growth so to avoid them becoming a tangle of twigs lower down with flowers high up, you cut them right back in early spring.
But even though you're cutting the top growth back, the root system is still developing and getting larger than when you first planted it. So they will grow back more vigorously in subsequent seasons then they did this year when newly planted. Also you'll get more flowers if you encourage them to grow as horizontally as possible, so get them to zig zag at 45 degrees up the trellis rather than let them grow up vertically.
Ive done this with my new ones, potted on, trained them against horizontal wires and they've got quite a lot of flowers on considering how small they were when I first got them.
They take many years to reach full maturity.
I live in west central Scotland - not where that photo is...
Might be better off growing through a shrub or with another clematis or something to help support the stems.
Good luck with your flammula, they are lovely and the scent is gorgeous. I have tried to grow it but lost it and a similar one. I think they like drier conditons that I can supply.