To store greens:

Cut beet greens from their roots. Keep dry, unwashed greens in a sealed plastic bag in the refrigerator up to 1 week. 

To prep greens:

Wash leaves in basin of lukewarm water to remove grit. Remove the thicker stems. Cut into appropriately sized pieces, depending on use.

To freeze greens:

Blanch washed beet greens for 2-3 minutes in hot boiling water. Immediately dunk in cold ice water to stop the cooking process. Then drain and pack into airtight containers. Freeze them in “balls” on a cookie sheet; then pop them into a Ziploc for the perfect portion.