!Help with blackberry bush in pot!

Second time growing blackberries in a pot on my terrace. This year I covered the pot and plant with bubble wrap so that the roots wouldn’t die like they did last year. Wondering why I’m not seeing new growth. See attached picture.

Please clarify your posting.

Is this the second time you have tried this or is it the second year for this same planting?

The amount of bubble wrap pictured is not sufficient to prevent root damage from cold temperatures. It would be better to temporarily fill the pot to the rim with bark dust or other slightly coarse material during the winter. For the side you need the whole roll of bubble wrap or else some other thicker insulating material, like an old blanket. Or bring the pot indoors on and off.