But zone 8 also extends well up into the Pacific Northwest where blueberries grow very well. Please tell us your location (city, state, country) so we can better address your question? The other factors of your climate such as heat and humidity in summer will affect how they grow. The zone designation really only tells us how cold it gets on an average winter.
Better yet, enter it into your personal profile so that your location will appear in the upper right of all your posts.