Hi, I have noticed that a lot of the wisteria flowers are not such a strong colour as usual, is this due to the lack of strong light this Spring?
Hi - have no idea why - mine are not yet fully in flower but look the same as they always do at this stage. They are on a south-facing front wall so probably get the best of whatever sunshine we do get - tho' not much of that lately. Is yours in a shady place?
It could simply be hungry. Try a balanced fertilizer such as Growmore, watered on.