Solanum linearifolium is evergreen and not completely hardy. It died in both the January cold in 2010 and the cold weather at the end of that year.
I re-planted it in March 2011. It has now reached 9’ and has been covered with these bright blue flowers for the last week or so. It should continue to flower for some time. I planted it on a sunny south facing wall and, even if it succumbs this winter, it will have made a big impact for two summers running.