I have a Cytisus ballandieri that has at some time (over 20 years ago) been been coppiced, and all the plant is producing is very long thin stems, (up to 20 foot high and about 1/2 inch thick,) with leaves at the top and no flowers. The stems are unable to suport there own weight, and bend in all direction. I have reacently pruned it down to about 10 to 12 foot. Is it posible to uncoppice it? and what is the best way of doing it?
Coppicing, you cut to the ground. I think what you have done is pollarding. It sounds as though this poor shrub has been incorrectly pruned in the past.
It may be best to cut your losses and start from a new plant. Cytisus are not very long-lived shrubs, I think 20 year + is pretty good going.
I'd bend some of the long branches down to the ground and layer them - that way you'll get lots of new plants
The C Battandieri that I knew best was trained to a sunny wall like a wisteria - it did really well there - I think it's the best way of using them as they can get very floppy if grown as a free-standing bush.