Select young, tender green leaves. Leaves on spinach should be at least 6 inches long. Harvest early in the day before heat from the sun causes greens to become limp. The amount needed to fill 1-pint is approximately 1 to 1 1/2 pounds.
Preparing for Freezing:
Wash thoroughly in an ice water bath to remove sand and insects. Rinse. Cut off woody stems and remove damaged leaves. Leaves can be left whole or chopped coarsely.
Water-blanch spinach for 2 minutes. Cool promptly and drain.
Best Freezing Method(s):
Transfer cooled, blanched greens into suitable containers. Seal, label and freeze. Leave 1/2 inch headspace.
As an alternative to blanching, spinach can be stir-fried until leaves are wilted (2 to 3 minutes) and packed into boilable bags. Seal bags, cool, pat dry and freeze.
Freezer containers should be moisture and vapor resistant and should not be prone to cracking or breaking at low temperatures. Containers should provide protection against absorbing flavors or odors and should be easy to label. Suitable packaging for freezing spinach includes freezer-grade plastic bags, rigid plastic containers or glass containers and heavy-duty foil containers.
Maximum Storage Time:
10 to 12 months at 0ºF. For best flavor, consume within 6 months.
Add green directly to dishes without thawing.
Tips & Shortcuts:
Carefully lift greens out of their water bath using a colander or strainer to leave any sand and grit behind.
Wrap unwashed greens in paper towels and store in plastic bags. If spinach greens are cut in the morning, they will last 2 to 3 days in the refrigerator this way. Cooked greens should be covered and stored up to 5 days.
Unblanched spinach that is frozen will be safe to eat, but the continued enzyme activity in the green leaves will damage the texture and destroy some of its nutrition. The two exceptions of which I'm aware are onions and bell peppers, which can be raw-frozen.