Wet newspapers and put layers around the plants overlapping as you go; cover with mulch and forget about weeds. Weeds will get through some gardening plastic; they will not get through wet newspaper. Good composting!
How to: Make a Modern, Space-Saving Vertical Vegetable Garden
Snowball viburnum, absolutely stunning.... They are stunning and I had five of these along my driveway at the previous property ~ withstood extreme heat, frost in winter and the occasional dusting of snow! AJ