I planted a laburnum tree about 3 years ago, its taken well and this year has started growing fast it's now 9ft high, I would like some advice on how to train it for the best shape, its grown 2ft in height this year but the new growth is bending over, will this straighten on its own or should I prune it shorter, or straighten it with a cane? its also producing more side branches on its north side (its planted in full sun), should I cut some of these off to balance it up? advice would be appreciated