I wouldn't recommend buying the store bought frozen spinach in this recipe. It makes the smoothie more watery in texture and the taste is awful. What I like to do is buy fresh spinach and freeze it along with the other ingredients. This way, the spinach is going to taste just as good. Whenever possible, use fresh spinach. If you cannot use it fresh, freeze it for future use. Also, no need to thaw the ziploc bag when you are ready to make the smoothie. Place all the ingredients into the blender right out of the freezer and blend.