March - get out there (covered in a thick jacket, thick gloves and glasses or goggles) with shears and hack it back right to the centre, then chop down any plumes left at their bases, and rake out the centre of the bush to remove any debris.

or if possible burn it down as that would be in its lifecycle anyway but most places it isnt practicle to do this . it burns realy hot and realy quick , does the plant good and saves you some work lol .