Canning – An Easy Guide to the Basics

From shovel to hoe to tomato to…where?  What comes after tomatoes? Canning your harvest!

There are many ways to preserve your harvest. Canning usually comes to mind first. Dehydrating and freezing are also other options.  But, if you have never done it before, it begs the question – “What does all that mean?”

There are some great posts out there that gives you specifics on a particular method or recipe.  This post is designed to tell you what canning means, and the equipment you need to do it.

Just so you know: This post contains affiliate links; if you click on a link and make a purchase I might make a small commission, but it does not affect the price you pay!

A Science Lesson

a basket of Roma tomatoes surrounded by home canned tomato sauce
Always use proper canning procedures to prevent Botulism

It’s time for a science lesson.  The biggest danger of canning is called ‘Botulism’ – also known as Botulinum Toxin and Clostridium botulinum. This is a bacteria that causes food poisoning in improperly canned and preserved foods. 

If you have not followed proper canning procedures, Botulism can begin growing in your canned goods within six hours. 

Botulism affects the nervous system.  It has no color, smell or taste, and is virtually invisible.  Botulism is fatal, so it is best to avoid it at all costs.

These are some signs your canned food may contain botulism:

  • Did not seal
  • Seal is broken during storage (the button will be ‘popped’
  • The jar is leaking, cracked, or flat is bulging
  • There is a POP , a spurt of liquid or foam when opening
  • Food is moldy, has an odor or is discolored

According to the CDC, these are some of the signs of Botulism poisoning:

  • Double vision.
  • Blurred vision.
  • Drooping eyelids.
  • Slurred speech.
  • Difficulty swallowing.
  • A thick-feeling tongue.
  • Dry mouth.
  • Muscle weakness.

If these symptoms occur after consuming home canned foods, get treatment immediately. For more information on this, please visit the CDC website.

The best rule of thumb for avoiding Botulism is: When in Doubt, Throw it Out!

Canning Your Harvest

a jar of home canned apple sauce; a jar of home canned apple peel jelly, red and green apples

Even with the scare tactics, canning your own produce can be done safely.  It also provides you with healthier, better tasting food to serve your family.  With the various canning and preserving methods, we put up no less than half of our food, often closer to 75%. We strongly prefer it to store-bought varieties.

Canning your harvest simply means to preserve your food using either a water-bath or pressure-canning process.  Both of these methods require using canning approved glass jars with lids that will seal securely to the jar. 

Lids are also called ‘flats.  They are a thin metal circle with a rubber gasket infused to one side.  When exposed to heat, the rubber gasket adheres to the glass rim, forming a tight seal. 

In order to obtain enough heat to secure this seal, the rim of the jar is first wiped clean.  Next, the flat is placed on top of the jar.  A metal ring is then placed on the jar and secured to ‘finger-tight’.

Finger-tight simply means it is as tight as you can get it simply by using your hands.  A ring tightened too much does not allow for suction during canning.

Once the canning process is complete, the jar is sealed and has completely cooled, rings can be removed.  This allows the rings to completely dry and prevents rusting.  Rings can be used as long as they are in excellent condition (not bent, no rust, etc.).

General Supplies for Canning

Whether using a water bath or pressure canning, both methods use some of the same basic equipment:

boxes of pint and quart canning jars; boxes of flats and rings for canning

Canning Jars

Heat-tempered, food safe – canning jars are designed for the high temperatures of canning.  It is imperative that you only use jars that are made for this process. 

Used mayonnaise jars, as well as others, are NOT SAFE for canning.  These jars are usually made of thinner glass and can (more likely WILL) shatter under high temperatures and pressure needed for safe canning.

Canning jars range in size:

  • 4 oz. – I use these for canning diced pimientos and chilies
  • 8 oz. (Half Pint) – normally used for jams, jellies, relishes, etc.
  • 16 oz. (Pint) – used for pickles, vegetables, fruits, sauces, etc. Can be used for jelly, relishes, etc.
  • 32 oz. (Quart) – used for vegetables, fruits, soups, sauces, etc. – usually when you need larger quantities in one use
  • Half-Gallon – These are normally used for storage purposes only.  Most water bath and pressure canners will not accommodate this size.  Use quarts instead for larger quantities

Pint and quart jars come in two sizes – wide mouth and regular mouth.  Both are suitable for canning.  I usually use wide-mouth for large fruits or vegetables in order to remove them from the jar more easily.  I use regular mouth for anything liquid – such as sauces.

canning utensils including slotted spoon dippers, ladle, jar lifter, bubble remover and funnel

Basic Canning Equipment

  • Large Mouth Funnel – used to safely pour product into canning jars
  • Jar Lifter – a wide based, hinged piece that allows you to lift the hot jars safely. Usually coated in vinyl
  • Bubble Remover – a thin plastic piece designed to run along the side of the filled jar to remove any air bubbles. Usually has convenient measuring marks to determine proper head space (usually comes as part of a kit)
  • Magnetic Lid Lifter – allows for safe removal of lids from hot water (this helps to keep lids sterilized)
  • Cooling Racks – used to place hot jars on. Allows air circulation around the jar during the cooling process
  • Flats & Rings – these come in both single use and multiple use styles.  For multiple use, I prefer the Harvest guard Reusable Canning Lids.  They may be a bit more expensive up front but are designed to be used multiple times. (I highly recommend the reusable lids made by Harvest Guard. They may cost a bit more up front, but in the long run, they actually will save you money.)
  • Clean Sterile Cloth – for wiping the rims of your jars. I use a clean white cotton washcloth that has been bleached – for safety measures.
  • Heat Resistant Gloves – to protect hands from steam and burning due to hot jars

What NOT to Use when Canning

  • Hermetically sealed jars (these are the ones that have a loose rubber gasket and a metal clip)
  • Any jars that once held spaghetti sauces, condiments, fruits, etc. and are not a true canning jar
  • Canning jars that have rusted, chipped or cracked
  • Paraffin Wax – your grandmother may have melted this wax and poured it over her jams and jellies. This is no longer considered a safe canning method.  Air bubbles can occur and will allow spoilage of your product. No matter how careful you feel you are being, never use paraffin wax for canning.

jars of home canned apple jelly and applesauce
Use proper jars, flats and rings for canning

Before You Can

Jars and flats must be clean and free from defects before you can.  This is the first line of preventing contamination in your canned foods.  Although rings do not have to be sterilized, they do need to be clean and free of dents, rust and bends.  The rings must fit securely over the jar and flat.

To Use Your Jars

Jars must be washed with mild detergent and rinsed well.  Check for chips, cracks and rust.  You can also place them in the dishwasher before using.  Allow the cycle to complete, and remove only the jars you will need to process at that moment (up to 7). 

A brand new box of jars still sealed in plastic are NOT considered clean!  These may still contain small pieces of glass from processing and dust.  All jars, whether new or re-used, must be thoroughly washed before using.

If the jars begin to cool before you have completed canning, reheat them by placing them in a clean pot and cover with boiling water.

Although using hot jars is required for canning, sterilization of the jars is not necessary IF the processing time is 10 minutes or longer in a boiling water bath.  The process will sterilize the jars. If processing time is anything less than 10 minutes, it is wise to sterilize your jars before using.

a cookie sheet filled with canning jars ready for sterlizing in the oven

To sterilize your jars, place them in a pot of boiling water for 10 minutes.  You can also place them on a tray in an oven. Slowly bring the temperature of the oven up to 220 degrees, and allow them to remain for at least 10 minutes before using.

Flats must be clean.  Please note:  the aluminum flats that come with canning jars or are purchased separately are for single-use only.  You will still need to check to make sure the rubber gasket forms a complete ring around the flat and is not damaged in any way. 

Multiple use flats are available.  I prefer the Harvest Guard brand.  They work well – and so far, I have gotten three uses out of the ones I have.  Still, you will have to check the gasket and flat for any possible damage or wear and tear before using.

Flats that are designed for multiple use are more expensive up front.  However, I have found they actually save me money in the long run, and prevents a mad rush to the grocery store if I run out in the middle of canning. 

Water Bath Method

a water bath canner and interior jar rack

The water bath method of canning uses a large 22-quart pot. It is large enough in diameter to hold seven quart jars, and tall enough to prevent the water from boiling over.

A rack is used to hold the jars and slightly elevate them from the bottom of the pan to prevent breakage.  The rack also comes with handles to easily lift and remove the jars from the boiling water.

Note:  When removing jars from boiling water, it is usually safer to do so one at a time.  Jars may not be stable and can shift when moving using the rack.

Foods that can be processed with the water bath method must be considered acidic, such as pickles, salsas, sauces, condiments (such as barbeque sauce, catsup, mustard, etc.), jams and jellies.

Check your recipe to determine if your product requires a water bath or pressure canning method.

Using a Water Bath Canner

jars of home canned stewed tomatoes
Tomatoes can be canned with the Water Bath Method

To use a water bath canner, place enough water in the pot to allow coverage of the jars by no less than 1”. Bring the water to a boil, and then place your jars in the pot, securely on the rack. 

Cover with the lid and return the water to a boil.  Once the water is boiling, start your timer.  The processing time will depend on the type of food you are canning and the size of the jar.  Each recipe will indicate processing time.

Once the processing time is complete, turn the heat off, remove the lid of the pot, and wait five minutes before removing your jars from the water.  This helps to stabilize the pressure in the jars. 

Using a jar lifter, remove jars one at a time. Gently and slightly tilt the jars to remove any standing water on top of the jar.  Be sure not to tilt too much, as the flats may not be completely sealed yet.

home canned jars of jelly cooling on a thick towel

Place jars on a rack for cooling.  You can also use several layers of absorbent towels.  I purchase inexpensive white bath towels for kitchen use.  These are used for cooling of canning jars as well as a place to put freshly washed large pots, bowls and other items to drain.

As the jars cool, you will begin to hear the popping sound of the final sealing process.  Once the jars are completely cool, check for proper sealing.  To do this, gently place your thumb in the center of each flat.  If it is slightly inverted and firm, it has sealed.

If your flat depresses, and then pops back up when your thumb is removed, sealing did not occur.  You will need to refrigerate this jar and use.  If you store it without refrigeration, contamination and botulism will occur, and the contents will not be safe to consume.

Pressure Canning Method

a pressure canner pot

A pressure canner is a large aluminum or stainless-steel pot.  The top is structured with a pressure gauge and release valve – also called a vent port or petcock. You should also have a small disc, which is actually a counterweight or weight gauge that fits over the vent port. This helps to regulate pressure.  

A ‘pop up’ button (or vent cover lock) is also located on the top. This button indicates the pot is under pressure. NEVER remove the top when this button is up!  To do so will cause serious to fatal injuries to anyone close by.

The underneath side of the lid has a rubber gasket. Both the lid and the bottom are notched. With proper alignment, the lid is locked in place.  The seal prevents steam from escaping during canning.

Pressure canners come in different sizes.  The 16-quart size is shorter, and will hold seven jars, regardless of size.  The 24-quart canner is tall enough to hold seven quart jars, or 14 pints, when stacked.

Your pressure canner should have a flat metal plate with holes in it.  This plate fits into the bottom of the canner to prevent the glass jars from resting directly on the bottom of the pot.  It also allows stem to rise and circulate during the canning process.

jars of home canned vegetable beef soup
Use a Pressure Canner for most Soups and Stews

Notes on Pressure Canners

A water bath canner is unable to reach temperatures higher than 212F.  A pressure canner can reach 240F, which allows the food in the jars to cook, as well as kill any contamination, such as botulinum toxin.

Where using a water bath canner requires the jars being covered with no less than 1” of water, a pressure canner works off of steam.  However, water is needed in a pressure canner.  Each size and type has its own requirements.  Please check the instruction guide to determine how much water yours will need.

A pressure canner is used for low to no acid foods.  Beans, carrots, squash and peas are examples.  Canning salt is usually added to each jar.  Hot to boiling water is then added to within a certain head space.

Head space may range from 1/4″ to 1”, depending on what is being canned.  Be sure to check your recipe to determine proper headspace. 

How to Use a Pressure Canner

Once water and jars are in the pot, lock the lid in place.  Be sure the counterweight is not on the pressure valve.  Turn the burner on low to medium heat, and allow the pressure to rise slowly. 

Steam will be coming from the pressure valve, but before the counterweight is put in place, the vent cover lock should be fully extended.  Once it is, place the counterweight on top of the pressure valve.

At this time, you will notice the pressure gauge begin to rise.  Just before it reaches the pressure recommended by your recipe, lower the heat a bit.  It may take a bit to regulate the proper temperature. This is done by slightly lowering or increasing the heat, waiting a moment until the pressure stabilizes, and then making additional adjustments as necessary.

Pressure canning requires a longer processing time.  Please refer to your recipe for the appropriate time.  Once that time is up, turn the heat off under the pressure canner.


the pressure gauge and counterweight on a pressure canner

Instead, allow the canner to cool down naturally.  This can take 30 minutes or more.  As soon as the vent cover lock has settled completely back down, remove the counterweight to allow any additional pressure to be released.

Using heat resistant gloves (potholder gloves work well), gently remove the lid.  Be sure the bottom of the lid is facing away from you.  Work slowly.  There is still steam in the pot, as well as condensation that can cause serious burns.

Remove the jars from the pot and place on a rack or multiple layers of towels that have been placed on a flat surface.  Allow the jars to cool completely.

Check for a proper seal (as noted above).  Place any jars that did not seal in the refrigerator.


canning ingredients including powdered Sure Jell, liquid Pectin, Pickling Salt

Canning Salt vs Table & Kosher Salt

It is advisable to use only canning salt when processing food in jars.  Also called ‘pickling salt’, this is the purest form of salt. 

Although Kosher or table salt can be used in a pinch, table salt will leave your finished product cloudy and appear unappetizing.  Salts other than canning also take longer to dissolve. 

If you do choose to use table salt, only use non-iodized.  It is not recommended to use salt-substitutes at all for canning purposes.


Vinegar is the flavoring and preservative for pickled products.  White vinegar is probably the most common type of vinegar used for pickling. 

Apple cider vinegar has more flavor and can be substituted.  However, apple cider vinegar will darken the vegetables. 

All vinegar must be no less than 5% acidity.  Vinegar should never be diluted when used for canning purposes.  Be sure to follow the recipe’s directions exactly. 

Only substitute other vinegars when the recipe calls for it.  Balsamic, white wine and other vinegars may not reach 5% acidity, and can cause your product to spoil.


Use produce that is fresh, with no blemishes.  Small blemishes may be cut out, with the remainder of the fruit or vegetable still useable. 

However, check to make sure the rest of it is undamaged.  Bruised and over-ripe produce will affect the flavor of your finished product.

Milk & Dairy Products

It is not advised to use milk or other dairy products in canning.  Some can be preserved by freezing, such as butter.  In spite of what may be listed as ‘canning friendly’ on the Internet, there is no true safe method to can these items.


Pectin is a natural starch found in fruits and vegetables. Combined with an acid and sugar, it is what makes jams and jellies solidified after cooling. 

Although natural pectin can be made, it is advisable to use the powdered version, such as Sure Jell.

A sugar-free variety is available. Just be sure to read the directions on how to use it properly. In some cases, using a sugar-free pectin may affect the color and shelf life of your final product.

Some recipes will call for liquid pectin. Liquid and powdered pectin is not recommended as interchangeable.


When a recipe calls for sugar it is primarily referring to granulated sugar, unless otherwise stated.  With very few exceptions, I use your basic granulated cane sugar.

You can, in some jam and jelly recipes use Splenda.  However, it does not work well in pickle and relish recipes.

As for Aspartame and Saccharin-based sweeteners, I won’t use them.  Aspartame loses its sweetness when used in canning; Saccharin leaves a bitter taste.

I hope this post helps to clear up some of your questions about canning your food.  If you still have questions, just drop me a line in the Comment section, or email me at

Additional Notes 

a stack of home canned jams and jellies with  decorative labels tied onto the jars with red and green ribbon

  • Thoroughly clean your kitchen, counters and cooking supplies prior to canning to help prevent bacteria
  • Allow the jars to cool completely. This can take up to 24 hours.
  • Remove the rings once the jars are cool. Check for a proper seal. Any jars that have not sealed can be placed in the refrigerator for immediate use.
  • Always label your jars. Add what it is, and the date it was canned. If you are selling your products or giving them as gifts, you may want to add a list of the ingredients as well.
  • If it gets to be too much, have a Canning Party!
  • Keep a running list of what you can, how much, and any notes in the Canning section of your Homemaker’s Manual

Canning – It’s a Lot of Work, but the Results are Worth It!

a 1/2-pint jar of jam with googly eyes surrounded by quart jars of pear halves

When the harvest comes in, you may feel overwhelmed. Canning is a lot of work. You wash. You peel. You mix. You fill jars. And sometimes, you burn your hands.

It may seem overwhelming now, but just wait. In the winter months all of your hard work will come in handy. You will be able to feed your family from your garden. The hard work will be just a memory. And very little tastes better than food you have grown, harvested and canned yourself!

Julie Murphree is a blogger, newspaper columnist, and speaker on all things ‘Living a Simple Life on the Farm’. She is the author of \\\'The Farm Wife – Living a Simple Life on the Farm. She and her husband have 60 acres in NW Louisiana where they actively work on living as sustainable as possible.

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