Hi I have recently renovated a house and am now moving onto the garden which has become very overgrown and is quite a daunting task. I have quite an old cherry blossom maybe 20 years old which has never really been pruned. It has grown really tall and is going to one side. It still blossoms but not as well as it probably should. What can I do to revive it? Do I need to get a professional in to prune it?