A couple of things to add to what has already been said re soil/compost. be aware that eventually the compost in pots/planters does lose its structure and becomes dust-like, and needs complete replacement. Some of our blueberries in pots languished after about four years, despite annual top ups and ericaceous feeding. New compost (not larger pots, they are already in big ones!) perked them up no end
I also grow some in the ground, which had a lot of ericaceous compost dug in to start with. They are planted through holes in membrane, and our soil is not acidic naturally. However, each year they get a thin spread over sulphur chips over the surface of the soil around the root area, as well as a dose of slow release azalea food, and they grow well.
Perhaps think about this for your blueberry hedge rather than a planter? Just a thought. Certainly makes watering more even, an dless frequent in dry spells