Many people would love to know how to can tomatoes. The process is easier than one may think and the results mean fresh tomatoes will be available for your family and friends year round. You can use fresh tomatoes from your own garden or even those you have bought from a store.

Select only disease-free, preferably vine-ripened, firm fruit if you want to learn how to can tomatoes successfully. Never choose tomatoes from dead or dying vines for canning. Unripened tomatoes are more acidic than ripened fruit and can be canned satisfactorily. Treat all ripe tomatoes – yellow, green, pink, orange, red, etc. – in the same manner.

Ohio State University makes the following recommendations to ensure safe acidity levels in whole, crushed, or juiced tomatoes:

Acid Pint Quart
Bottled lemon juice 1 tablespoon 2 tablespoons
Citric acid 1/4 teaspoon 1/2 teaspoon
Vinegar (5 percent acidity) 2 tablespoons 4 tablespoons

Add acid directly to the jars before filling with product. If desired, add up to 1 tablespoon of sugar per quart to offset acidic taste. Vinegar may cause undesirable flavor changes.

The use of salt is optional in all canned tomato products. Salt is used in canning only for flavor or color protection. Even though both boiling water bath and pressure processing are commonly used when canning tomatoes, pressure processing will result in higher quality and more nutritious canned tomato products.

Cans or Jars?

To begin you will need several quart jars with rings and lids. It is important to sterilize the jars, rings, and lids you will be using. This can be accomplished by boiling the lids, rings, and jars in water for 5 minutes. This can also be done in the dishwasher. It is important to keep the jars warm so leave them in the dishwasher to keep them warm or you can use a low setting in the oven to keep the jars warm until it is time to use them. Once the jars are sterilized and ready you can begin to prepare the tomatoes. It is not hard to learn how to can tomatoes. You can use Roma tomatoes or your home grown tomatoes. If you are using tomatoes grown in the garden it is best if they are ripe but still firm. One bushel of tomatoes will yield around 18 to 20 quarts of canned tomatoes. A half bushel will yield 9 to 10 quarts and 7 to 8 medium sized tomatoes will fill one jar.

The process

To begin, boil enough water in a large pot to cover the amount of tomatoes you have decided to can. Place the tomatoes in a plastic container or in the sink and then pour the boiling water over them. If you use a container, be sure it can fit safely in your sink. Leave the tomatoes in the boiling water for a minute and then quickly rinse them in cold water or submerge them in a container of very cold water. Next you will need to remove the skins and any green parts of the tomatoes with your paring knife. This should be an easy process after the tomatoes have been blanched. After you have removed the skins and any green parts of the tomatoes, cut them into medium sized pieces. Place these medium sized pieces into the large cooking pot and bring it to a boil. Keep your tomatoes at a light boil for around 30 minutes. Use a large metal spoon to remove any of the pink foam that accumulates on the surface. The next step will explain how to can tomatoes. Once you have boiled down your tomatoes for about 30 minutes, it is time to fill your jars. Add a teaspoon of salt to each jar and use a funnel and a ladle to put the tomatoes into the jars. It is important to leave ¼ inch of space or head room at the top of the jars. This will allow space for the tomatoes to expand as they cool. Place the ring and lid on the top of the jar and then turn the jar upside to cool for about 20 minutes. Turning the jar upside down as it cools will seal the lids with the heat from the tomatoes. The lids will pop when they have been correctly sealed. Then all that is left is to enjoy your hard work with fresh tomatoes now available regardless of the season.

More information on how to can tomatoes can be obtained here.