How to Can Tomatoes

For many people, the best part of summer is the abundance of fresh produce. Tomatoes are a popular ingredient, known for their versatility that manages to enhance any meal. Tomatoes, however, do not last forever and will rot if they aren’t consumed fast enough. This means that it is important to preserve them if you want to enjoy them throughout the year. Tomatoes are easy to preserve and can be canned easily by following some simple steps.

There are a few different ways that you can use for canning tomatoes. The most common being Water Bath Canning, Pressure Cooking, and Pressure Canning. While Pressure Cookers can be used for canning, they may not maintain the steady pressure that is required for safe canning. For this reason, it’s better that you opt for Pressure Canners rather than Pressure Cookers.

In both Water Bath Canning and Pressure Canning, the preparation process for tomatoes remains the same. In Water Bath Canning, the food is processed by boiling it in water for a specific amount of time. This is the preferred method for canning acidic food. In Pressure Canning, the food goes through a process that uses the steam in the pressure canner. This allows faster canning under higher temperatures. This method is one of the best when canning low acidic food.

In this post, we will go over both these canning techniques so you can figure out which one suits you best.

Key Ingredients for Canning Tomatoes

Tomatoes: You can use any variety of tomatoes you like, but the meaty variety that has fewer seeds works best for canning. In this guide, we are canning 12 pounds of tomatoes. If you are using quart-sized jars, you will be able to fit around 3 pounds of tomatoes into one can, or 1½ pounds in a pint-sized can.

Lemon Juice: Lemon juice ensures that your tomatoes have a consistent acidity that makes them safe for canning. We recommend you use bottled lemon juice as it has a consistent pH. You will need 2 tablespoons of lemon juice for every quart-size can and 1 tablespoon for every pint-size can.

Canning Jars: You will need 4 quart-sized cans or 8 pint-sized ones.

The first step in canning tomatoes is removing their stems and washing them thoroughly. Tomatoes that are still on the vine should be removed with scissors to avoid any bruising. Next, tomatoes should go into the refrigerator for around thirty minutes to chill before you start working with them. Once your tomatoes are clean and chilled, you can start with the canning process.

Getting Ready for the Canning Process

1. Place your tomatoes in a large pot with water and bring it to a boil. While your water is coming to a boil, cut a small “X” into the bottom of all your tomatoes. This will make the peeling process easier. Once your water is boiling, add in your tomatoes carefully and let them blanch in the water for 2-3 minutes and after that, transfer the tomatoes to an ice water bath so that they cool quickly.
2. Once they have cooled to a point where you can handle them, peel the skin from your tomatoes and core them.
3. Prepare your cans by washing them with soap and hot water so that they are well sterilized. Boil your lids in water for 5-7 minutes to make sure they are well sterilized as well.
4. Place a kettle of water on the stove and bring it to a boil. This will be our canning liquid.

How to Can Tomatoes using a Water Bath

1. Fill each of your cans with the blanched tomatoes. You can squish them in slightly to make sure they are well packed.  Add 2 tablespoons of lemon juice to your quart-sized jars or 1 tablespoon to your pint-sized ones. Top off your cans with the water from your kettle, leaving ½ inch headspace for your quarts and 1 inch for your pints.
2. Once your cans are all filled, clean them with a damp cloth to remove any oils that may prevent sealing during the canning process. Place the lids on your cans and screw on the rings so that they are just “finger-tight”. If you screw them on too tightly, your cans won’t seal correctly. 
3. Place the pot you will be using for your water bath on the stovetop and add your cans to it carefully using jar tongs. Once all your cans are in position, add hot water to your pot. You need to add enough water so that all your cans are immersed an inch below water.
4. Maintain the heat on the stove such that the water remains boiling during the entire canning process. Keep an eye on the water level and add more water if the level goes down. Your pint-sized cans will be ready in 40 minutes and your quart-sized ones in 45 minutes.
5. Once the processing time is up, remove the cans carefully and let them cool undisturbed for at least 12 hours. Once cooled, you can remove the rings from the cans and clean the cans with a wet cloth, label them with their canning date and store them at room temperature.

Tips for Canning Tomatoes using a Water Bath

• Always keep an eye on the water level. If the water level goes below your cans, you will end up ruining the entire batch. Top off the water as needed.
• Adjust processing times according to your elevation:
  •       1,001- 3,000 ft. – add 5 minutes
  •       3,001- 6,000 ft. – add 10 minutes
  •       6,001- 8,000 ft. – add 15 minutes
  •       8,001-10,000 ft. – add 20 minutes

How to Can Tomatoes using a Pressure Canner

1. The preparation process for pressure canning tomatoes is the same. You need to fill in your cans with tomatoes and add in the lemon juice. You need 2 tablespoons for your quart-sized cans and 1 tablespoon for your pint-sized cans.
2. Top off your cans with hot water from the kettle, maintaining ½ inch headspace for quarts and 1 inch for pints.
3. Prepare the pressure canner by adding 2 to 3 inches of water to the bottom. Place the canning rack at the bottom so that your tomato cans don’t come in direct contact with the bottom of your pressure can.
4. Once your cans are all filled, clean them with a damp cloth to remove any oils that may prevent sealing during the pressure canning process. Place the lids on your cans and screw on the rings so that they are just “finger-tight”.
5. Place your prepared cans into your pressure canner carefully and close the lid of the canner. Turn on the burner and let the canner vent for a few minutes. When you see steady steam, you can place the regulator on the vent pipe.
6. After you place the regulator on, the pressure reading on the canner gauge will increase. Adjust the heat so that the pressure is maintained at 11 PSI (pounds per square inch) for 25 minutes or as per your pressure canner’s instructions.
7. Check the processing time and after it finishes, turn off the heat and allow the pressure to drop naturally. You can monitor the pressure using the pressure gauge on your pressure canner. Once it drops to 0, open the lid and carefully lift out your cans using a jar lifter and allow them to cool down to room temperature.
8. Once cooled, you can remove the rings from the cans and clean the cans with a wet cloth, label them with their canning date and store the cans at room temperature.

Tips for Canning Tomatoes with a Pressure Canner

• Allow your pressure can to depressurize naturally for safe canning.
• Be precise with your timing for best results.

How to Can Diced and Whole Tomatoes

Both of the methods above allow you to can either diced tomatoes or whole tomatoes. The choice is completely up to you! Choosing whether to can the tomatoes whole or diced depends on how you plan on using your canned tomatoes.

In both of the canning methods above, we make use of whole tomatoes. Whole tomatoes have a fresher flavor as they keep more of their natural sweetness.

Diced tomatoes are versatile, and you will find it convenient to use them to make sauces, chili, or even soup. To can diced tomatoes, once you have your tomatoes blanched and cored, go ahead and dice them into the desired size. Once you have them diced, you can use either the Hot Water Bath method or Pressure Canning method to can them.  

Frequently Asked Questions

Which tomatoes are best for canning?

Tomato varieties that are meaty with fewer seeds work best for canning purposes. Some varieties that you can try are Amish Paste, San Marzano, and Better Boy tomatoes.

How long do canned tomatoes last once opened?

Once you open your canned tomatoes, make sure you store them in the refrigerator and use them within 5-7 days. Unopened cans will last for 12-18 months if they are stored correctly. However, make sure when you are using the oldest cans first. Make it a habit to label your cans with the canning date to make this process easier for you.

Conclusion

Tomatoes are rich in vitamins, iron, magnesium, and antioxidants that make them a healthy choice. Pair these health benefits with the versatility of tomatoes and the ease of cooking with them, and you have a winning combo! So give these canning techniques a try. The tips are sure to make the process easier for you and you will be canning tomatoes for years to come!