Posted: 18/06/2013 at 19:58
I feed my wisteria from November to March once a month with liquid tomato feed. Then every fortnight from March till flowering. I follow the same pruning as fidgetbones. My wisteria is flowering now and it's 4/5 years old.
I highly recommend feeding any plants with which have long or dramatic flowering periods with liquid tomato feed prior and during the flowering period.
eg. Clematis (group 2), Wisteria, Canna, Passiflora
Another fully organic method is to cut up banana skins into small chunks and dig them into the surrounding soil. They decompose quickly and release potassium into the soil.