I strongly recommend blanching before freezing, but it is technically possible to forgo the blanching process. If you freeze asparagus without blanching it first, you still need to prep it by removing the unwanted parts and washing the stalks, so you're not saving yourself that much time. Keep in mind that unblanched asparagus will deteriorate more quickly in the freezer, losing its color, taste, and texture. Unblanched defrosted asparagus is best used in things like soups where the difference in texture will be less noticeable.