There's nothing like eating fresh tomatoes throughout the summer, and preserving some of your harvest lets you enjoy them all year. Canning tomatoes is surprisingly simple. There's no need to buy an expensive pressure cooker or water-bath canner, which is no more than a large pot; you can easily use your largest soup or stock pot to get the most out of your summer bounty.
Choose a metal pot that is at least 4 inches taller than the pint-sized canning jars. Make sure it has a secure, tight lid.
Wash the canning jars, lids and rings in hot, soapy water. Rinse the soap from the jars then keep them in warm water until they're ready to be filled.
Wash the tomatoes.
Submerge the tomatoes in boiling water for 1 minute. Then move them to a large bowl of cold water.
Peel off the tomato skins and cut out the cores. Halve or quarter the tomatoes, if desired.
Place the tomatoes in a pot and add just enough water to cover. Boil over medium heat for 5 minutes.
While the tomatoes are boiling, place a round, metal rack, like a cake-cooling rack, at the bottom of the canning pot. Fill the pot with water and bring to a boil.
Pour the boiled tomatoes into the canning jars, leaving 1/2 inch of space at the top of the jar. Add canning salt and lemon juice to each jar.
Wipe the rims of the jars dry with a clean cloth. Place the lids on the jars, rubber sides down, then tightly screw on canning rings.
Place the jars into the canning pot using the jar lifter, making sure the jars aren't touching each other or the sides of the pot. Add more water, if necessary, so the jars are covered with at least 2 inches of water. Then bring the water back to a boil.
Place the lid on the pot once the water is boiling. Boil for 40 minutes (at altitudes less than 1,000 feet) or 45 minutes (at altitudes above 1,000 feet).
Using the lifter, remove the jars from the boiling water. Set them on a rack or countertop and cover them with a towel. Let them cool for 48 hours. The jar lids will make a pinging noise as they seal.
Check the jar lids to make sure they're sealed; each lid should be concave once they've cooled.
Label the jars with the contents and date, and store in a cool pantry until ready for use.
Quart-sized canning jars can also be used, but they're often too large when canning in normal kitchen pots.
Never use canned tomatoes if the jars are leaking or if the contents smell bad.