how long should you freeze fresh spinach or kale to use in smoothies
Kent County Delaware food safety
HI, From a food safety perspective, as long as you wash it, remove woody stems, dry it and then freeze it quickly, it will be safe in the freezer.
To keep the color and flavor, it is recommended to wash and cut off woody stems and then blanch greens for 2 minutes (collards for 3 minutes) and then dry and pack with 1/2 inch of head space. You could also pack it in freezer bags.
The length of time it should stay in the freezer is more about product quality. After too long, the leaves may get freezer burned or the color/ flavor may be off. The recommended length of time for keeping fruits or vegetables in the freezer is 8 months. Hopefully, you will use it up faster than that though.
For more information about freezing you can go to the website for the National Center for Home Food Preservation. www.nchfp.org.
Hope this helps.