The clue here is that the bottom of the plant is browning. I suspect you let the plant dry out in the summer and it takes a few months for the damage to show. It is okay to cut off the lowest branches that are brown and give your spruce the look of a cone on a stick with a bit of trunk showing. The brown foliage will not turn green again so just clip it off. The Alberta Spruce are not heavy drinkers but growing in a container it really needs extra water in the summer. It would also appreciate protection from the hot afternoon sun. Keep growing, Marianne Binetti