Hydrangea paniculata 'ILVOBO' Bobo® PP 22782 / PROVEN WINNERS® COLOR CHOICE® Bobo®. Bobo® Panicle Hydrangea. This compact Peegee type hydrangea flowers white during the summer and as the flower heads age, they tend to lengthen. With a mature size of 3-4 feet, it fits well into the smaller garden. Grow in full sun for best flower production. Since this species flowers on current seasons wood, one can prune it back heavily in late winter to early spring just before new growth begins. I prefer to leave the spent flower heads on the plant through the winter to give it some winter interest. The flower heads are also useful in dried flower arrangements.