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Whether you’re a gardener with a bumper crop of cucumbers or you just scored an amazing deal at your local farmers market, there’s only so much space in your refrigerator to hold it all. Fresh produce only lasts for a few days in refrigeration, so what’s the alternative to freezing? Canning! Food preservation is a time honored tradition that’s been used for generations. It’s not difficult to do once you know the process.
There are many reasons why you may choose to preserve your own food by home canning. Preserving your own food is eco-friendly because it cuts down on food waste. How many times have you tossed out fresh green beans or strawberries because you forgot you had them in the crisper? By canning it from the start, the produce will last longer because it will be shelf stable.
Preserving at home is also fresher and tastes better because you are able to shop or pick your product at peak ripeness and adjust the seasonings to your liking.
There are two canning methods: hot water bath canning and pressure canning.
Hot water canning is used exclusively for high acid food with pH values of 4.6 or lower. The acidity can be natural (as it is in most fruits, jams, and jellies) or added, as in pickled vegetables and most tomatoes (bottled lemon juice is a common acidic ingredient in these recipes). Acidic foods contain enough acid to block the growth, or destroy botulinum bacteria rapidly when heated.
To get started with the canning process, you’ll need some basic canning equipment:
- Canning jars and seals: Only use jars specifically designed for canning, like mason jars. When you first purchase canning jars, they will come with a ring and self-sealing lid. You can reuse rings but the canning lids are single use only.
- Funnel: Makes filling jars easier and less messy.
- Lid Wand: For easy removal of lids and rings from boiling water.
- Ladle: For filling jars.
- Water bath canner: For high acid food.
- Pressure canner: For low acid food. (It’s recommended that you don’t try to use your Instant Pot for pressure canning.)
- Jar lifters: These rubberized lifters make removing jars safely from hot water.
- Clean cloths: For wiping down jars, lids, and rims of jars.
Most of the steps for hot water bath canning and pressure canning are the same. The actual processing methods will differ when it comes to operating the canners, but the key steps are covered below. Refer to the USDA Complete Guide to Home Canning page to get step by step instructions on how to operate a pressure or water bath canner in detail.
1. Start with a tested canning recipe. The first step in canning is to start with a verified, tested canning recipe. A tested recipe (like this home canned tomato sauce) will provide you with the correct weight and/or measurement of the produce, additional acid, salt, water, etc., in order to preserve your food. The recipe will also give you the correct processing time for the jar to reach the correct temperature that will kill off any bacteria in the jar and the recommended headspace in order to create a solid vacuum seal.
2. Wash all jars, lids, and rings in hot, soapy water.
3. Sterilize. Jams, jellies, pickles, or any products processed less than 10 minutes need to be sterilized. To do this, put the jars and lids into a large pot. Fill the pot with enough warm water so it is 1-inch above the tops of the empty jars. Bring the water to a boil, and boil for 10 minutes. You may have to boil longer if you live at a higher altitude. Reduce the temperature to a simmer and leave the jars and rings in the water until it’s time to fill the jars. Place the lids in a smaller pot of simmering water. (If your recipe calls for processing the jarred food for 10 minutes or longer, you can skip this step.)
4. Cook. Make the food according to your recipe.
5. Fill your jars. Lay out a kitchen towel on to the counter. Use the jar lifters to remove the jars from the hot water, pouring out any excess water. Place the jars onto the kitchen towel. Use the lid wand to grab the rings and lids from the pots of water. Place them on the towel. Place the funnel on a jar and fill the jars with the jam or produce. Be sure to leave the recommended headspace according to the recipe so you will have a vacuum seal, and use a special tool or small silicone spatula to remove any bubbles in the jar.
6. Clean them. With a clean kitchen cloth wipe the rim of the jar to remove any liquid or food residue. Anything left on the rim can interfere with the seal.
7. Cap them. Place a self-sealing lid onto the rim of the jar. Place a ring over the rim and tighten to make sure the lid is in place.
8. Process your preserves. Use the jar lifters to place the jars into a hot water bath or pressure canner. Process for the length of time dictated by which vegetable/recipe you’re canning and the altitude at which you live.
9. Cool. Once the jars have processed for the correct amount of time, remove them from the canner with the jar lifts and place them on the kitchen towel. Let them sit for several hours to completely cool. While cooling, your jars will start to pop, creating the vacuum seal.
10. Check the seal. Once cooled, remove the rings. The rings are no longer required to hold the lids. Place them in storage—they can be reused until they start to show signs of rust or warping. Press down on the center of your jars to ensure they have sealed completely. Any lids that spring back are not vacuumed sealed and can be placed in the refrigerator and eaten first.
11. Store. Label your jars with the contents and the date. Store in a cool, dry place until you are ready to eat. Once you open a jar, it must be stored in the refrigerator. You’ll also need a band to hold the lid in place again once opened.
The National Center for Home Food Preservation’s comprehensive guide is a great place to start for beginners, and a handy resource for veteran canners.
From Ball, the company that makes those great canning jars, a free guide on how to do water-bath canning safely.
By the author of “Food in Jars: Preserving in Small Batches Year-Round,” Marisa McClellan’s how-to guide on canning is a classic.
Serious Eats’ guide—also by Marisa McClellan—offers a brief history on canning, as well as a technical description of why it works, with cool instructional photos.
The Kitchn interviews canning maven (who else?) Marisa McClellan for tips even canning pros could benefit from.