These weeds are about 4 feet high. I can either weed whack them now (late September), or wait until early spring. Will I have a much easier time cutting them back in spring? I'd prefer to do it now, but if it saves a lot of effort, I'll wait 6 months. After cutting them back, I intend to cover with landscape fabric, and mulch. My aim is to stop the weeds coming back and plant some bushes. This is near Philadelphia, PA.