I’m putting my flat on the market in a few weeks and wanted to plant up my window boxes to make my balcony look more appealing for the photos and viewings. Please can anyone suggest some plants that will look good through autumn and winter (and ideally into spring!) without my having to keep refreshing the window boxes? I’d be very grateful for any suggestions, especially for inexpensive plants as I need to keep costs down. I am in London so we don’t have too many frosts.