Unless my monitor is badly adjusted, this is Canna 'En Avant' - a
popular hybrid in municipal plantings, though not to be despised
because of that. If you can get virus-free plants (not easy at the
moment), it is a very rewarding variety capable of producing many
vigorous shoots which can flower throughout the summer. A sunny site,
rich soil and lashings of water is the order of the day for these
gaudy plants. They are also well suited to large containers provided
you use a very good quality compost (sorry, but 'peat-free', soil-less
types simply cannot hold onto essential nutrients long enough) and
give regular applications of liquid feed.