Blueberries are available in stores all year round. If you can’t get fresh ones, there are always frozen blueberries in the aisle with the frozen products. Depending on what you want to do with them, you have to choose between fresh or frozen. In most cases, you can use frozen berries without any problems, because the small berries kind of disappear in the bakes anyway. The blueberries in these Blueberry Streusel Bars merge into one thick blueberry layer, so frozen berries work perfectly here ;)