Home canning is experiencing a resurgence of interest for all sorts of reasons. Imagine the shelves of your pantry stocked with homemade pickles, tomato sauce, and jams. Whether you are blessed with an overabundance from your garden or want to indulge in the art of “putting by” with peak produce from your farmers’ market, canning captures the best flavors for year-round enjoyment! Here’s an overview on how to can!
NOTE: Guidelines for safe canning are always being updated so use current information. Your local county extension office has a wealth of information about canning.
What Is Canning?
Think of canning as a form of cooking. Instead of cooking one meal for immediate consumption, you are cooking food that you can save and store away for months! Why do this? Because canning allows you to capture the best flavors at the peak of season—all-year long! Imagine the amazing taste of garden-fresh tomato sauce in the middle of winter.
Canning is a method used to preserve fresh food in jars at high temperatures for a long period of time, killing microorganisms and inactivates enzymes that could cause food to spoil. The heating process pushes air from the jar, creating a vacuum seal as food cools. With no air, nothing can keep growing and food won’t spoil.
When you get started with canning, one of the first things you’ll likely read about is botulism poisoning. Botulism is an illness caused by the botulinum toxin, which is produced by Clostridium bacteria. These bacteria occur naturally throughout the world and don’t usually present a threat to people. However, they are a very hardy type of bacteria and are capable of thriving in low-acid, low-oxygen environments, like those created when we can foods. If food is canned improperly, the bacteria may develop and produce their deadly toxin, making the food unfit for consumption.
To prevent this from happening, we need to either make the environment inside our canned goods inhospitable to the bacteria or sterilize it entirely. This is why it’s so important to know what sort of food you’re planning on canning (more specifically, whether it is a low- or high-acid food) and why you need to use the correct canning method (water-bath or pressure canning) for the type of food. This is explained further below.
The bottom line: Botulism is serious—poisoning can result in paralysis, difficulty breathing, or even death—so always follow proper canning procedures!
The Two Canning Methods: Water-Bath and Pressure Canning
To can your produce properly, follow one of these methods: water-bath canning or pressure canning.
Which method you use depends on what sort of produce you are canning. To figure out which method to use, consider the “acid test.” Is the produce you are canning high or low in acid? In other words, does the food have a high pH or a low pH? A pH of 4.6 is the dividing line; a pH higher than 4.6 means less acidity (“low-acid foods”) and a pH lower than 4.6 means more acidity (“high-acid foods”).
To prevent the development of harmful bacteria, which thrive in a low-acid environment, low-acid foods must be processed using pressure canning, while high-acid foods may be processed using either water-bath canning or pressure canning.
1. Water-Bath Canning
Water-bath canning is the simpler of the two canning methods, as it involves boiling your canned foods in a big pot of water. There are pots specifically designed for this—called water-bath canners or boiling water canners—that consist of a large container, a rack insert, and a lid. However, any large, deep pot will do, as long as you have a rack that fits inside it and a lid.
Water-bath canning is a lower-temperature canning process, which makes it safe ONLY for high-acid vegetables and fruits. (Recall that low-acid foods must be processed in a pressure canner.) High-acid foods typically include most types of tomatoes (for juice, sauce, or paste) and berries (for berry jams and jellies). Their natural acidity—in addition to time in a boiling water bath—helps preserve them safely without the use of high pressure. Nonetheless, you’ll still need to take some precautions and follow the proper canning process.
Harmful bacteria won’t survive in high-acid conditions, so pickles, relishes, salsas, and most tomatoes are safe for the beginning canner. (To be on the safe side, you can add extra acidity with lemon juice or vinegar.) Jams, jellies, fruits, and tomato and fruit juices are also highly acidic. They all can be safely processed in a boiling water bath.
If you’re among the folks recently struck by the home canning bug, we recommend starting with water-bath canning, as it’s not as big of an investment as pressure canning and is more straightforward. Let’s call this “no pressure” canning!
To learn more about water-bath canning, see: Water-Bath Canning: Supplies and Getting Started
2. Pressure Canning
Pressure canning involves the use of a pressure canner, which is a device that consists of a large pot, a rack insert, and a fitted lid with a pressure valve. The high pressure inside the canner allows the temperature to get much hotter than it could in a water-bath canner; this kills off any harmful bacteria and sterilizes the food.
Low-acid vegetables such as green beans or corn MUST be processed at a higher temperature—at least 240°F at sea level—to prevent the growth of bacteria. To maintain the high temperatures for the proper length of time, you need to invest in a pressure canner. This process is not for the novice.
Pressure canning is also used to preserve low-acid foods such as meats, poultry, seafood, chili, and other low-acid vegetables that require a higher temperature to raise the heat inside the jars above boiling, enough to kill harmful bacteria. Pressure canning can be fun and satisfying, but it requires a more expensive outlay, more learning, and more time.
If you’d like to preserve low-acid foods but don’t have access to a pressure canner, consider preserving them in other ways, which are not only safer, but taste better, too. Broccoli, corn, and green beans taste much better when frozen and have better texture. Blanch them briefly in boiling water, cool down quickly in ice water, and pack them in bags or containers for the freezer.
To learn more about pressure canning, see: Pressure Canning: How to Use a Pressure Canner
There are a few basic supplies which you’ll need in order to can at home:
Canning jars, lids, and seals: Only use clean jars without cracks or nicks in them. We recommend using the tried-and-true Ball brand mason jars.
Water-bath canner or pressure canner:
For water-bath canning, it isn’t necessary to purchase a special water-bath canner as long as you have a pot that has a fitted lid and is large enough to fully immerse the jars in water by 2 inches—and that will allow the water to boil rapidly when covered. You’ll also need a rack that fits inside the pot or canner—a cake cooling rack would do.
For pressure canning, only use a pressure canner (not a pressure cooker) made specifically for canning.
Jar lifter: These tongs help to pick up hot jars and safely take them out of hot water after processing.
Ladle: A ladle helps to spoon food into canning jars.
Funnel: A wide-mouth canning funnel make it easier to fill your jars without spilling.
Where to Find Canning Supplies
Many websites, hardware stores, craft stores, and other retail outlets sell kits that incorporate most of these canning essentials, sometimes along with other handy tools such as magnetic lid lifters, headspace-measuring tools, regular kitchen tongs, bubble removers, and jar scrubbers (though you probably already have kitchen tools that can perform these jobs).
Except for single-use lids, which you should buy new every year, you can reuse mason jars, screw lids, the water-bath canner, food mill, and stockpot for many years. You’ll often find these items in good condition at thrift stores, yard sales, or in the basement of a friend or relative who’s given up on canning. If you find a nice canner with a domed cover but no rack, you can probably find one that fits your kettle in a local hardware store, farm store, or online.
Make sure you check each jar, especially the rim, for small cracks or chips each time you use it. Also, don’t attempt to use a rusty canner; I’ve learned the hard way that rust spots may spring leaks during processing, causing the flame on my gas burner to flicker or dousing it entirely, and leaving me scrambling to find a substitute canning pot.
10 Tips to Know Before You Start Canning:
Always use fresh produce that’s in peak condition. Canning is not for overripe fruits or vegetables.
Gather all your ingredients and equipment and make sure you have everything you need before you start. Halfway through the process is no time to be running to the store.
Follow recipes and directions exactly. No improvising; your family’s safety depends on doing this correctly.
Sterilize the jars and keep them hot until you are ready to fill them.
Use real canning jars and new 2- piece lids. Keep the flat part of the lid hot; the screw ring needs to be clean but not hot.
When you fill the jars, leave ¼ inch of the top; this is called head space and can vary depending on your recipe. If you fill jars too high, the canning lids will not seal properly. Wipe the jar rim and threads clean and put on the lid. Tighten it only finger tight.
Place jars on the rack in the boiling water so that they are covered by at least 1 inch of water. Count processing time once the water has returned to a boil.
Of course, make sure your jar is sealed properly with that “popping sound.” Jars that don’t seal can NOT be stored; put in the fridge and use within a few days.
In general, your canned foods should last all year long, as long as they are stored in a cool, dry place. A broken seal is a sign air has gotten in. A bulging lid or a lid that seems corroded or rusty is also is a sign of spoilage.
When you do open your cans, if you ever see mold or bubbles or a cloudiness, that is a sign that the seal popped and it’s spoiled. Do not eat!
To avoid canning burnout, start with a small project at first. Try a few jars of salsa instead of a bushel of tomatoes. Prepare the recipe and get the water in the canner boiling.
I love to can pickles. Most pickles need only 5 minutes in boiling water. Lift out the whole rack to remove the jars and spread them out to cool. If you hear popping noises, it is the jars sealing. Once the jars are cool check the seal; the center of the lid should be depressed. If a jar doesn’t seal put it in the fridge to eat right away. The sealed jars can be labeled and stored in the pantry for winter.
The sight of those gleaming jars full of delicious food is very satisfying!
Ready to get started? See our guides for water-bath canning here and pressure canning!