area is 12 ft X 4 feet. It is open to alley so I do not want to put a bench or table in area. I am unable to do much weeding (darn old age and creaky joints). All suggestions will be helpful. One butrerfly bush, one lime green hosta already in area and some type of small but tall sunflower that mutilplies overnight and overuns.located zone 6 Pennsylvania. would like to have some winter interest in garden. thanks