Bulletin #4040, Let’s Preserve: Leafy Greens

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spinach greens for sale at a farmers market

Bulletin #4040, Let’s Preserve Leafy Greens (PDF)

Developed by Penn State Cooperative Extension with special project funds from Extension Service, U.S. Department of Agriculture.

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Recommended Varieties

Spinach: Bloomsdale, Melody, and Viking are good varieties when grown in early spring or late fall.


A bushel weighs 18 pounds and makes 3 to 9 quarts. An average of 28 pounds makes a 7-quart canner load; 18 pounds makes 9 pints. An average of 1-1/4 pounds makes 1 pint of frozen greens.


Preserve only freshly harvested greens. Leaves should be mature, attractive in color, and tender. Discard wilted, discolored, diseased, or insect-damaged leaves.


Wash only small amounts of greens at one time. Drain and continue rinsing until water is clear and free of grit. Don’t soak greens. Cut out tough stems and midribs. Place 1 pound of greens at a time in a cheesecloth bag or blancher basket and steam 3 to 5 minutes, or until well wilted. Or place 6 cups of raw greens at a time in 1 gallon of boiling water and blanch for 2 to 3 minutes after the water returns to a boil. Cool greens in several changes of cold water and drain.

Freezing Procedure

Don’t freeze more than 2 pounds of food per cubic foot of freezer capacity per day. Fill pint- or quart-size freezer bags to a level of 3 to 4 inches from their tops and squeeze out air. Leave 1-inch headspace, seal, label, and freeze. Before freezing, bags may be inserted into reusable rigid plastic freezer containers for added protection from puncture and freezer burn.

Canning Procedure

Wash jars. Prepare lids according to manufacturer’s instructions. If desired, add 1/2 teaspoon of canning or pickling salt per quart. Fill jars loosely with drained, not-blanched greens, leaving 1-inch headspace. Add fresh boiling water, leaving 1-inch headspace. Wipe jar sealing edge with a clean, damp paper towel. Add lids, tighten screw bands, and process jars in a pressure canner.

To process in a pressure canner, place jar rack, 2 inches of water, and sealed jars in canner. Fasten lids, and heat canner on high setting. After exhausting steam 10 minutes, add weighted gauge or close petcock to pressurize the canner. Start timing the recommended process when the desired pressure is reached.

Process Times

Recommended Hotpack Process Times in a Pressure Canner at Different Altitudes

Jar Size Process Time (min) Dial gauge canner Weighted gauge canner
Canner gauge pressure at altitudes of
0-2000 ft. (lbs) 2001-4000 ft. (lbs) 4001-6000 ft. (lbs) 6001-8000 ft. (lbs) 0-1000 ft. (lbs) Above 1000 ft. (lbs)
Pints 70 11 12 13 14 10 15
Quarts 90 11 12 13 14 10 15

Regulate heat to maintain a uniform pressure. When processing is complete, remove canner from heat. Air-cool canner until it is fully depressurized. Then slowly remove weighted gage or open petcock, wait 2 or more minutes, and unfasten and carefully remove canner lid.

After processing is completed, remove jars from canner with a jar lifter and place them on a towel or rack. Do not retighten screw bands. Air-cool jars 12 to 24 hours. Remove screw bands and check lid seals. If the center of the lid is indented, wash, dry, label and store jar in a clean, cool, dark place. If lid is unsealed, examine and replace jar if defective; otherwise, use new lid, and reprocess as before. Wash bands and store separately. Greens are best if consumed within a year and safe as long as lids remain vacuum-sealed.

Nutritional Information

Average Content of a Serving (3 oz.) of Leafy Greens

Raw Cooked
Mustard Greens Spinach Mustard Greens Spinach
Calories 21 16 19 11
Carbohydrates, g 4 2 3 2
Fats, g 0.2 0.2 0.2 0.2
Protein, g 2 1.3 3 1.2
Sodium, mg 21 1.25 18 97
Vitamin A* 75 60 50 50
Vitamin C* 100 40 40 25

* Expressed as percentage of the U.S. Recommended Daily Allowances (US RDA). Other vitamins contained at insignificant levels.

Information in this publication is provided purely for educational purposes. No responsibility is assumed for any problems associated with the use of products or services mentioned. No endorsement of products or companies is intended, nor is criticism of unnamed products or companies implied.

© 2000

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