Preserving Greens

Many greens are enjoyed raw in salads. A few are incorporated into soups or casseroles. Unfortunately, the most tender of the leafy greens, leaf lettuce, does not preserve well. The preferred method of preserving hearty greens is freezing because it provides a higher quality product than canning or drying. Heartier greens such as spinach, mustard greens, beet tops, collards, kale, and Swiss chard can be frozen. As a low-acid food, greens can only be pressure canned. Although there are directions for drying greens, drying produces a poor-quality product because of the high-water content of the produce.

To Freeze Greens

• Select young, tender green leaves. 
• Wash the leaves thoroughly and cut off woody stems and fibrous ribs.
• Water blanch collard greens for 3 minutes and all other greens for 2 minutes.
• Cool promptly, drain, and package, leaving ½-inch (1.25 cm) of headspace.
• Seal and freeze in amounts typically used in a favorite recipe. 
• More mature leaves might be chopped, blanched, drained, and blotted dry to be tray frozen. 
• Tray frozen greens will separate more easily, and you can take out only the amount you want for a meal or recipe.
• While most frozen vegetables can be cooked directly from the freezer, greens that are frozen as a solid block should be partially thawed before heating to prevent overcooking the vegetables. This is not necessary for tray frozen greens.

To Can Greens

• Can only freshly harvested greens with leaves that are tender and attractive in color. Discard wilted, discolored, diseased, or insect-damaged leaves.
• It takes about 28 pounds of greens to make a canner load of 7 quarts, or 18 pounds to make a canner load of 9 pints. 
• Wash small amounts of greens at a time in a colander under running water. If washing in a pan, also wash small amounts at a time and lift from the water—do not pour off water as soil will deposit back onto the food. Drain water and continue rinsing until the water is clear and free of grit and sand. Cut out tough stems and midribs. 
• Use only a hot pack. 
• Place 1 pound of greens at a time in a blancher basket, and steam 3 to 5 minutes or until they are well wilted. 
• If desired, add ½ teaspoon salt to each quart jar. 
• Fill jars loosely with steamed greens and add fresh boiling water, leaving 1 inch (2.5 cm) headspace. 
• Place lids on jars.
• Process pints for 70 minutes in a dial gauge pressure canner at 11 pounds pressure or a weighted gauge canner at 10 pounds pressure. Increase process time to 90 minutes for quart jars. Increase pressure in a dial gauge canner to 12 pounds at altitudes between 2,001 and 4,000 feet, to 13 pounds pressure between 4,001 and 6,000 feet, and to 14 pounds pressure between 6,001 and 8,000 feet. Increase pressure to 15 pounds in a weighted gauge canner at altitudes above 1,000 feet.
• The reason for the long process time is that greens pack together, preventing the circulation of liquid between the leaves, and heat is slowly transferred to the center of the jar by conduction.

Drying Greens

• Drying greens produces a poor-quality product because of the high water content of the produce. However, they are suitable as an ingredient in soups, casseroles, sauces, and stews. 
• If drying greens (chard, kale, turnip greens, or spinach), use only young, tender leaves that have been very thoroughly washed and trimmed.
• Water blanch small amounts for 1½ minutes or steam blanch (no more than 2 inches deep) for 2 to 2½ minutes. Blanching relaxes tissues so that pieces dry faster, improves quality, and destroys harmful bacteria. 
• After blanching, place in cold water just long enough to stop the cooking.
• When greens are cool enough to handle, about 120°F (49°C), drain thoroughly and place in a single layer on a drying tray. Blot excess moisture if necessary.  
• Usual drying temperature is 140°F (60°C). 
• Dry for 6 to 10 hours until crisp and brittle. Watch greens closely at the end of the drying time so that they do not scorch.
• Store cooled product in an airtight container in a cool, dark place. 
• Properly stored dried vegetables will keep well for 6 to 12 months at room temperature. Refrigerate or freeze the dried products for longer storage.
• Three pounds of dried greens will yield about ¼ pound when dried. 
• Unlike other dried vegetables that require soaking to be reconstituted, leafy greens can be rehydrated with the hot liquid in which they are cooked.

References:

National Center for Home Food Preservation. (n.d.-a). "Freezing Greens (Including Spinach)". University of Georgia.

National Center for Home Food Preservation. (n.d.-b). "Selecting, Preparing, and Canning Vegetables Spinach and Other Greens". University of Georgia.

Zepp, M., Hirneisen, A., & LaBorde, L. (2023, June 8) "Let's Preserve Freezing Vegetables." Penn State Extension.