Posted: 29/09/2016 at 09:48
You can get clear sheeting for putting over plants from Garden Centres. I wouldn't use blue tarpaulin. The plants you mention, except, perhaps, Penstemon, are quite hardy and should be OK with just the shelter of the wall. They won't mind some rain. I have a cheap polycarbonate cold frame by the kitchen wall for overwintering plants. You could even make one.
I would leave foliage as winter protection, trim it in the spring.
Last edited: 29 September 2016 09:49:24