They may be too young yet or in too much shade or have been pruned wrongly so the flowering shoots have gone or they are in need of nutrients or water if they are in pots.
They are not gross feeders but you could try giving them a drink of suitably diluted tomato food to see if that prompts them into making flower buds.
Vendée - 20kms from Atlantic coast. "We don't stop playing because we grow old; we grow old because we stop playing." - George Bernard Shaw
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They may be too young yet or in too much shade or have been pruned wrongly so the flowering shoots have gone or they are in need of nutrients or water if they are in pots.
They are not gross feeders but you could try giving them a drink of suitably diluted tomato food to see if that prompts them into making flower buds.
"We don't stop playing because we grow old; we grow old because we stop playing." - George Bernard Shaw
Thanks for that, Obelixx - very useful !