Home-canned tomatoes bring a garden-fresh taste to soups, stews, chilis, and spaghetti sauces all year long. For each pint of canned tomatoes, you will need 1-1/4 to 1-1/2 pounds ripe tomatoes; for each quart, you'll need 2-1/2 to 3-1/2 pounds ripe tomatoes. Choose unblemished tomatoes for canning and wash well in cold water.
Peeling Tomatoes. Wash firm unblemished tomatoes. To remove the skins, dip tomatoes in boiling water for 30 seconds or until the skins start to split. Immediately place the tomatoes in cold water. When cool enough to handle, remove the skin and core with a paring knife. If you like cut the tomatoes in half. Be sure to save any juices.
Filling jars with tomatoes. Place a wide-mouth funnel in a hot, clean pint or quart canning jar. Ladle whole or halved tomatoes into the jars along with any juices from preparing the tomatoes. Add 1 tablespoon lemon juice to each pint jar or 2 tablespoons lemon juice to each quart jar. The lemon juice raises the acidity of the tomatoes to ensure safe canning. Add boiling water, leaving 1/2-inch headspace.
Sealing jars. Remove the funnel; wipe the jar rim with a clean, damp towel to remove all traces of food. Food on the rim prevents a perfect seal. Position the prepared lid and screw band on the jar and tighten according to the manufacturer's instructions. Set each jar into the canner as it is filled. The jars should not touch. Cover the canner. You will need to process the tomatoes in a boiling-water canner for 40 minutes for pints and 45 minutes for quarts. Begin timing when the water returns to boiling.
Checking the seal. When the jars have cooled, press the center of each lid to check the seal. If the dip in the lid holds, the jar is sealed. If the lid bounces up and down, the jar isn't sealed. Unsealed jars should be stored in the refrigerator and used within 3 days, or you can reprocess the tomatoes within 24 hours. Label the jars with contents and date. Your tomatoes with keep their optimum quality for 1 year.