Learn How to Make and Can Jam With This Helpful Step-by-Step Guide

• Boiling-water canner ($57.98, amazon.com) or similarly deep pot (think lobster size) 
• Canning rack ($22.99, amazon.com) or cake-cooling rack, to fit into the pot (some canners come with canning racks)
• Jars, lids, and bands (from $22.99 for 12, amazon.com)
• Jar-lifting tongs ($7.99, amazon.com)
• Headspace-measuring tool ($4.49, amazon.com)
• Clean dish towels
• Labels (from $13 for 120, amazon.com)
• Timer

Canning supplies are also available at hardware stores, supermarkets, and supercenters. For more information on supplies, consult freshpreserving.com (the official website of Ball, the consummate canning resource).

Be sure to check your supplies before you start. Bands should screw evenly over lids; jars should be free of scratches or chips, which could cause seal failure during processing or sealing.

Next, remember that you should not reuse lids. Jars and bands can be recycled, but the flat lids are onetime use only.

Last but not least, cool carefully. Never place hot jars directly on kitchen counters; the glass might crack. Use a dish towel or a cooling rack instead. 

Ingredients (makes four half-pint jars)

• 3 pounds plums (or other stone fruit such as peaches, nectarines, or apricots), pitted and quartered
• 3 cups organic sugar
• 1 tablespoon fresh lemon juice
• 3⁄4 teaspoon kosher salt

Wash jars and lids with soapy water, dry bands, and set aside. Place jars in a large pot and cover with water. Bring to a simmer. Put lids in a separate pot of hot water. Leave jars and lids in water until ready to fill.

Combine plums, sugar, lemon juice, and salt in a stockpot over high heat.

Bring to a boil, mashing with a potato masher. Skim scum off top.

Boil, skimming and stirring frequently, until bubbles slow and you can see chunks of fruit showing through top and mixture clings to a spoon, falling off in languid clumps, 10 to 12 minutes. Pick up and discard skins with a fork, if desired.

Lift jars out of hot water one at a time, draining water. Ladle hot jam into hot jars using a wide-mouth funnel, leaving 1⁄2-inch headspace. Slide a nonmetallic spatula or chopstick between jam and jar to release trapped air bubbles.

Wipe rim and threads of jar with a clean, damp dish cloth. Remove lid from hot water. Place lid on jar. Screw band down evenly and firmly, just until resistance is met.

Place in canner and lower into water. Put lid on canner. Bring water to a boil. Start keeping time after water comes to a rolling boil. Process 1⁄2 pint jars for 10 minutes at a gentle but steady boil.

Turn off heat and remove canner lid. Let canner cool five minutes, then remove jars and set them upright on a dry towel or rack. Do not retighten bands. Let jars cool 12 to 24 hours.

Once cool, check lids for a good vacuum seal by pressing on center of each. If center is pulled down and does not flex, remove band and gently try to lift lid off with your fingertips. If lid does not flex and you cannot lift it off, seal is set. Wipe lid and jar surface with a clean, damp cloth to remove food particles and residue. Label. Store jars in a cool, dry, dark place.

For more recipes, check out our Jam, Preserves, and Jelly collection.