Posted: 22/10/2012 at 21:40
Sorry to disagree, flowering rose, but Taylors Clematis says the exact opposite:
"Good feeding is important. In order to produce good flowers the plants should be fed by a good general, branded fertilizer following the manufacturer's recommendations- twice a week. Start feeding by mid-spring and continue until just before flowering. Do not feed during flowering as this will tend to reduce the flowering period."
See here: http://www.taylorsclematis.co.uk/plant-care.html