Wash well; remove large, tough stems. Cut large leaves (collard greens, chard) in pieces.
Blanch in boiling water. For kale, spinach, chard, mustard, beet or turnip greens, boil for 2 minutes. Boil collard greens for 3 minutes. Cool immediately and drain well.
Leave about 1/2 inch of headspace.
2 to 3 pounds of kale or similar greens = approximately 1 pint frozen.
Page 1 - Vegetable Freezing Guide: Blanching and Packing
Page 2 - Preparation and Blanching Times for Specific Vegetables
Page 3 - Cooking Frozen Vegetables