I have six climbers and among them are two rather new (a year and half old) climbers (one red and one pink) that are growing tremendously, they are covering the wall of 2x5 meters wall completely since a couple of months WITHOUT giving any flower buds! They did give some flowers in the spring time, but after that, no buds at all anymore, they keep on growing, growing, without no flower... Other climbers are blooming regularly. Is there anything I can do to help them produce flower buds? The instruction says I don't have to cut the branches, but they look very messy. May I cut them? If yes, when?