Freezing greens

Greens can be frozen and stored for up to 9 months in a ziplock bag, and it takes less than five minutes. This is from http://www.uga.edu/nchfp/how/freeze/greens.html

Freezing

Greens
(Including Spinach)

Preparation – Select young, tender green leaves. Wash thoroughly and cut off woody stems. Water blanch collards 3 minutes and all other greens 2 minutes.

Cool, drain and package, leaving 1/2-inch headspace. Seal and freeze.