Could anyone help please ? We have a tired pyracantha hedge about 8 feet tall and 4 feet deep which has many thin branches. It is growing against a mesh wire fence. There is new growth on all of the branches but only on the last foot, the remainder being leafless. I would like to thicken up the growth and restrict the hedge to a depth of about 18 inches. In this stage of its' life would it be possible to cut back the branches to achieve this. Would it survive such a drastic prune and when would it be best to do this.What after care would be needed to ensure survival and long term, what pruning regime should be employed to limit the growth but still achieve flowering and berries. Thank you.