* Frozen bananas make creamy, delicious smoothies. Bananas need to be frozen for at least 8 hours. I like to keep a stash of frozen bananas in my freezer so I can make smoothies whenever I want (all the time, actually). Peel them, cut them in half, and store them in an airtight container. The riper the bananas, the tastier and sweeter the smoothie. Green bananas = bland smoothies.