Preserving Produce With Water Bath Canning

Are you a fan of eating farm-fresh food all year round? Perhaps you’re partial to pickles or homemade jam? Here’s how you keep your harvest for a rainy day.

Home gardens and farmers’ markets are bursting with seasonal produce. Don’t you wish you could keep this tasty bounty all year long? With some dedication and enough processing time, you can! Water bath canning can save you money and provide you with a store of healthy jams, pickles, and other condiments — with none of the added preservatives you’d find in their grocery store counterparts.

What’s the difference between canning and pickling?

Canning is a vacuum-sealing method used to preserve perishable foods for long-term storage without refrigeration. Pickling refers specifically to preserving food in a solution of brine or vinegar; pickles may be canned for long-term storage or not.

A "quick pickle" (sometimes called a refrigerator pickle) requires the same sterilization steps as traditionally canned food, but isn't processed to produce a vacuum seal, and therefore requires refrigeration. Any quick pickle — be it pickled green beans or crispy cucumbers — will need to be refrigerated and consumed within a week. For longer-term storage, water bath canning is necessary to produce a vacuum seal while maintaining a high enough temperature to kill bacteria.

Most fresh foods contain a lot of water, which is what makes them so highly perishable. Both preservation methods help to curb spoilage, which accelerates with the presence of microorganisms, oxidation, and bruising. For these reasons, it’s important to use the highest-quality fruits and veggies you can find.

Before you get started with water bath canning, we’ll share the tools you need, some tips on how to process canned foods safely, and enough recipes to keep you busy throughout the annual harvest.

Under pressure

The National Center for Home Food Preservation is responsible for testing and approving water bath canning and pressure canning recipes. You may have seen recipes online that use the oven, microwave, and even the dishwasher for canning. None of these methods are recommended by the NCHFP — for first-time canners, it’s best to stick with the reliable, proven methods: water bath canning and pressure canning.

So, time for some high school chemistry: Water bath canning preserves acidic foods with a pH of 4.6 or lower. Some recipes use added lemon juice or citric acid to bring up the total acidity, helping prevent botulism. Improvise at your own risk! If not following tested recipes, be sure to check the acidity level with pH strips from the hardware store.

Pressure canning, not to be confused with pressure cooking, is meant for low acid foods like potatoes, meats, and chili. These items aren’t acidic enough to prevent bacterial growth, so a larger psi (that's "pounds per square inch," a measure of pressure) and heat is needed to cook away bacteria and remove oxygen from the jar.

With the right tools, you can

Even though it’s called canning, the most important components are jars, lids, and rings. It’s possible to source metal cans, but they’re single-use and need special sealing equipment. Glass jars, on the other hand, can be reused again and again, as long as they don’t have any cracks.

The flat metal jar lids that accompany your glass jars are intended for single use, while the metal canning rings that hold the lid in place can be reused many times. Wire swing-top or glass-lidded jars from the thrift store are pretty, but we don’t recommend them for safe canning.

A special canning funnel has a wide opening that fits right into the mouth of the jar, making it easier to pour brine and avoid splatters. Even with a funnel, the best way to get liquids into jars is with a ladle or a heat-safe measuring cup with a spout.

During the canning process, you’ll be handling a hot glass jar that's been submerged in boiling water. An oven mitt and regular tongs won't suffice — it’s both hot and slippery, and we wouldn’t want you to shatter it. To protect yourself, use a specialized jar lifter or grabber made for canning: it’s a springy clamp lined with a grippy material that keeps the jar secure and your hands away from the heat.

Next, you need a canning pot, tall stockpot, or Dutch oven with a lid. It needs to be tall enough to hold the canning jars upright with a rack underneath while allowing the jars to be covered by at least 1-2 inches of water. The canning rack creates a layer between the direct heat of the burner and the glass jars, lets the water to circulate around the jars on all sides, and helps hold jars in place to reduce the chance of rattling and breaking. Any metal rack works — even an Instant Pot insert — as long as it fits at the bottom of the pot. Some home canners use coils of balled-up foil in place of a rack, but this method is less stable and won't allow for proper water circulation around the jar.

The space left between the level of brine and the top of the jar is called the "headspace." Your recipe will tell you how much headspace is necessary for the jar to properly form a vacuum seal when processed. Canning kits may include a "bubble remover tool," which is a combination headspace ruler (each of the "steps" on the wide end of the tool measures a quarter inch) and spatula.

No bubble tool? A rubber spatula or wooden chopstick will easily remove air bubbles trapped in the jar. Use a ruler or tape measure (outside the jar) to measure headspace.

Canning or pickling salt is a finer grain salt than Kosher and doesn't contain any anti-caking agents. If you want to use Kosher salt, you can, but you'll need to adjust the amounts. The substitution ratio is usually 1-1/4 cup Kosher salt for each cup of pickling salt.

Recipes for success

Sterilization eliminates germs to help prevent food poisoning. Start first by sterilizing your glass jars. Here are a few methods:

If your dishwasher has a sterilization setting, you can clean a whole case of jars at once. A regular dishwasher cycle may not be hot enough to properly sterilize your jars.
Preheat the oven to 275 degrees F. Place just-washed jars mouth-side down on a lipped cookie sheet. Dry in the oven on the center rack for ten minutes.
Boil the jars in a covered pot of water for ten minutes. This convenient method allows you to use the water in your canning pot to sterilize while also getting it up to temperature for processing.

In all cases, let the jars air-dry afterward. Towel drying may leave lint or threads on the inside — not something you want in your precious canned goods! Next, sterilize your lids and rings by placing them in a small saucepan of simmering water until you’re ready for them.

Pack it up, pack it in

There are two main methods for packing your jars for water bath canning. Raw packing — commonly used for vegetables — is when you put cold items into your jar and pour hot brine over them. Hot packing involves blanching food with the brine first, and pouring the mixture into the jar. This helps remove excess air and stops small pieces from floating above the brine line.

When it’s time to pack raw food, tilt the jar on its side as if you’re building a ship in a bottle. Tall items like green beans or wax beans will line up more easily.

You can "split" jars into smaller sized jars if needed — but you’ll have to employ some elementary division or fractions. Pick the right size for your shelves. If a recipe makes a quart, you can split it between two pint jars or four cup jars — or even one pint jar and two cup jars. Do keep this rule of thumb in mind, though: you can always go down in size to smaller jars, but shouldn't use a larger jar than the recipe calls for. The processing time given in a recipe may not be sufficient for larger jars than indicated.

Trust the process

Once your jars have been packed, you're ready for the final step: processing. Processing is where the canning magic happens — your prepared food goes into the hot water bath and the temperature is raised to a point sufficient to kill bacteria and create a vacuum seal.

Before closing up your jars with the lid and ring and putting them into your canner, wipe the top of the jar rim with a towel dipped in white vinegar to remove any bits of food or brine that might interfere with the seal.

When it’s time to process, use the jar lifter to lower your filled jars onto the canning rack, making sure the hot water bath covers the top of the jars by one inch or more. Heat a few cups water in a kettle to top it off if needed. Process your jars for the time indicated in your recipe — just make sure to start your timer after the water has returned to a full rolling boil!

Have a towel ready to put the jars on when processing is complete — placing hot jars directly on a cold surface (like your marble countertop) may shock and break the glass. When finished, remove the jars from the boiling water bath with your jar lifter and place them on the towel. Leave your processed jars undisturbed for 24 hours, away from sources of heat or cold, such as open windows, air conditioning, hot pipes, or sunlight. Within the first half hour, you may hear the pop of the cans as the vacuum pulls the lids downward.

After 24 hours, check your seals. The center of the lid should be pulled down to create a smooth surface that doesn't spring back when you press on the center. If a seal fails, change the jar and reprocess within 24 hours or store in the fridge and consume soon. Don’t forget to date the cans to remind yourself to eat their contents within the year. Store them in a dark place at a temperature between 50 and 70 degrees Fahrenheit.

Fruits of your labor

Once you’ve got your canning set up, you can go wild building up your pantry. Here are just a few of our favorite projects to get you started:

Get down with regular blueberry jam or try your hand at persimmon jam, jellies, butter, and curd.
Fresh green beans are an excellent alternative to the cucumber for your next pickling project.
Enjoy dilly beans as a perfect picnic side dish or as an accompaniment to cocktails (Bloody Mary, anyone?). With fresh dill, dill seed, and red pepper flakes, these savory pickled beans pack just the right amount of punch. Try my recipe below!
How amazing would it be to have apple pie filling ready to pop into a pie shell at any time? Each canned quart makes one eight- to nine-inch pie.
Speaking of apples, apple cider syrup is a condiment for sweetening drinks and a replacement for honey, sugar, and maple syrup.
Buy summer tomatoes in bulk to preserve them whole, crushed, or as paste.
Make your own salsa, Korean barbecue sauce, and ketchup without preservatives or wasteful plastic packaging.