Wash collard greens thoroughly in cold water
Remove thick stems and tough ribs
Chop or leave leaves whole, as desired
Blanch in boiling water for 2 to 3 minutes
Transfer immediately to ice water to stop cooking
Drain well and pat dry
Portion into freezer bags or airtight containers
Remove as much air as possible
Label with the date
Freeze promptly
Use within 10 to 12 months