Sorry but I can’t help you with your question only pass on a simple observation;

With ‘Roesse Blacky’ having the parentage of (‘Gruss aus dem Bodethal x Rohess Alrami’) x ‘Stad Elberg’ it should have inherited some of it’s parents prolific flowering qualities. Gruss aus dem Bodethal is synonymous with Black Prince (Banks 1861)- so one of its parents has been around a while and stood the test of time.

A similar colour fuchsia was introduced by Thornley in 1972 called 'Ravensbarrow', however this was a single flowered cultivar.

Not being a variety that seemed destined for the show bench I have seen very little of this cultivar, although I have seen it advertised almost everywhere, perhaps that should tell us something?

I will ask a fuchsia nursery owner friend of mine to see if he can throw any light on the matter.

Tight

I grew a couple R.B's in hanging baskets, and was not overly impressed by the vigour of the plant, but this being the first year, I was hoping for better results next year. My growing conditions may not have been ideal as they had to make do with full sun all summer, although I did water daily when needed. I gave a neighbour a cutting early on and his plant seemed to do better than mine. He is a 'Miracle-Gro' person, so this may account for it.
This was my first year with fuchsias so everything was very 'trial and error'..........and a lot of learning.