FAQ about Canning. Searchable answers to questions about how to can, and solutions for common canning problems. You've got this!

Q.  Help! After all my hard work, my pickles turned out hollow inside. What went wrong and how can I avoid it next time?

A.  Hollow pickles can be caused by a variety of factors. Here's how to avoid hollow pickles: 

1) Use fully matured cucumbers. Cukes should have a firm flesh and be a pale green color inside. Do not use cucumbers that are white inside. Your cucumbers should not have any hollow pockets inside at all. If you are growing your own cucumbers pay attention to what the seed packet says is the amount of time needed to reach maturity before picking.

2) Once the cucumbers are harvested, process them as soon as possible. Storing them too long can lead to hollow pickles once processed.

3) Follow the recipe directions precisely - you don't want too weak or too strong a brine during fermentation.

Good luck - you've got this! 

Q. My recipe mentions "headspace." What is headspace in the world of canning recipes?

A. Good question! Headspace refers to the space necessary at the top of the jar for a vaccuum to form and for the jar to seal. Do not fill your jars to the top. If your recipe calls for a specific amount of headspace to be left, have a ruler handy to ensure you can follow the recipe exactly. We prefer a silicone ruler because it is easy to clean and food-safe. Note: avoid touching your food with aluminum or galvanized metal. 

Q. How long do I process my jars? When do I start my timer?

A. To time your jar processing correctly, you should start your timer:

• when the water has returned to boiling for boiling water canning.
• When the pressure is reached when you are using a pressure cooker.

Don't jump the starting gun! For safe processing, wait and start your timer at the correct time. 

Q. What kind of salt should I use for my canning recipes?

A. Use pure granulated salt if available. Un-iodized table salt can be used, but the materials added to the salt to prevent caking may make the brine cloudy. Do not use iodized table salt; it may darken pickles. The most simple way to find the right salt is to look for salt specifically labeled as "Canning and Pickling Salt." 

Q. Why didn't my jelly turn out right - it's too soft!

A. When evaluating the quality of your jellies, consider these reasons for too soft jelly:

Too much sugar

Insufficient cooking

Too much acid

Lack of Pectin

Prolonged boiling

You'll get it perfect next time! 

Q. Yuck, my jelly came out stiff and tough. What did I do?

A. Stiff jelly means the jelly was either overcooked or you added too much pectin.

Tough jelly can also mean you added too much pectin and/or overcooked. Tough jelly can also be the result of too little sugar. 

If a jelly is gummy, but not stiff or tough, it means it was overcooked.

Never fear, practice makes perfect! 

Q. Why is my jelly cloudy?

A. There are several reasons your jelly turned out cloudy.

Green fruit

Improper extraction

Pouring jelly into conainters too slowly

Allowing cooked mixture to stand too long

Canners often hear the advice to follow the recipe exactly, but more recipes need to point out that speed matters for some steps. Good luck!

Q. What is processing?

A. Processing is subjecting the jar of food to a heat treatment. All canning products should be processed. Your recipe will indicate if the processing should happen in a hot water bath or a pressure cooker. 

Q. When do I use a hot water bath?

A. Hot water baths drive air from jars and secure air-tight seals. Air left in the jar may cause discoloration, loss of flavor and even result in spoilage.

The kinds of products that need hot water baths include preserves, marmalades, conserves, jams and frut butters.

Remember, follow your canning recipes exactly for success and safety! 

Q. Why are my pickles an "off" color?

A. Potential reasons pickles may be discolored:

Hard water may have been used in the preparation. Water can be softened by boiling for 15 minutes, chilling it and allowing it to stand for 24 hours, and then straining it. This is a lot of work! Can you skip it? Yes. Hard water is not harmful in itself; the only reason for softening the water is if you are entering your pickles in a competition.

Pickles can also become discolored if dark vinegars, ground spices or table salt are used.

Finally, pickles will beome green if you marinate them in unlined copper or brass and black if you leave the in iron or zinc.

The eye often tells the mouth if something will taste good, so this is a great topic to understand if the color of your pickles matters to you!  

Q. Why did my pickles get shrivelled?

A. Shrivelled pickels are disappointng and unappetizing. You can avoid them next time with this information; it was most probably one of two problems (or both!)

Specifically, too much salt, sugar or vinegar was added at the beginning of the curing. Or, if you followed the recipe exactly and have shrivelled pickles, it means they were overcooked.

Better luck next time - you can do it!  

Q. Eww, my pickles feel slippery. That's not right, is it?

A. Definitly not right! Throw them away immediately. if your pickles feel soft or slippery that means the container has been invaded by bacteria! 

This means the pickles were not processed coreectly, either they were left uncovered with the brine during fermentation or they were not processed or sealed correctly. 

Safe safe! - when in doubt, throw it out! 

Q.) None of my jars sealed! What happened?

A.) If your jars didn't seal or do not retain a vacuum, first of all, DO NOT taste or use!

Potential causes (and there are many!)

Jars were not properly processed. Always folllow recipe exactly for processing times and steps.

Jars were not covered by water during water bath processing. Make sure jars are covered by at least 1 - 2 inches of water.

Jars were inverted after processing. Always keep jars right-side-up.

Food was on the rims of the jars. Wipe your jar rims with a clean, damp towel before applying the lids. The recipes frequently mention this step, but never explain why it's essential! 

Nicked, chipped or cracked jar or jar rim. Examine all jars before use! 

Too much headspace in jar which prevented it from forming a vacuum. Follow the recipe guidance on how much headspace to leave. We have a headspace measuring tool in our canning supplies inventory. They are inexpensive and a great help! 

Q.) Why would food or liquid boil out of jars during processing?

A.) There are four possible culprits:

Your jars may have been filled too full. Always leave the correct amount of headspace.

You may have packed your fruits or vegetables into the jars too solidly or too tightly. Pack jars snugly but not too tightly.

You may have processed the jars at too high a temperature. Monitor the temperature of water bath canners during processing.

Or, you may have processed your jars at too high pressure. For pressure canning, keep an eye on the pressure throughout the processing.

Good luck!  

Q.) Why did the green color of my vegetable fade when I canned it?

A.) Fading green colors is a natural reaction to heat processing. If you want to address this next time, a little baking soda or lemon juice added to your cooking liquid may help reduce color loss. 

Q.) What should I can if I want a project that is simple and easy?

A.) Tomatoes are one of the easiest foods to can. The only caveat, the tomatoes must be prime quality: red, firm and ripe - not overripe. Good quality tomatoes are easily processed in a boiling water bath. Note: do NOT can overripe tomatoes. They have lost acidity and for that reason are no longer safe for canning in a water canner. Have fun! 

Q.) I followed the recipe for canned tomatoes and was careful to leave the correct amount of head space. Now that they've been on the shelf for a few months, I'm noticing that the amount of head space seems bigger. Is the liquid evaporating? Does this mean they didn't seal correctly?

A.) We found an answer for you from America's Test Kitchen. Tomatoes are watery and as they heat, they release their air along with juices. During processing and cooling a HARMLESS gap can occur in the jars. (Whew!) If a large gap appears at the top of the jar but the lid is still fully sealed, the food inside the jar is safe to eat. Good job leaving the correct amount of head space!

Also, always be sure to wipe off any sticky residue from the jars before storing them and check the seal again before opening.

Q.) I know it's safe to do water bath canning for tomatoes, and that most vegetables need pressure canning to be safe to eat. So, what if I add some vegetables to my tomatoes? Like for a marinara sauce recipe. Is it still safe to use a water bath?

A.) Good question! And the answer is yes, it is still safe to use the water bath canning method for canned tomato recipes that include some vegetables, with the following caveat - follow your recipe exactly! The recipe developer will have added the correct amount of vegetables to keep it safe to water-bath can. Do not increase the amount of vegetables - to do so may lower the acidity of the product too much. And, if you make a half batch, keep the ratio of tomato to vegetable the same. 

Q.) When do I need to use a pressure canner instead of water bath canning? 

A.) It's all about what you are canning. Low acid foods, such as most vegetables, must be processed in a pressure canner in order to be free of botulism risk.

Here is a link to an extremely detailed explanation of when, why and how to use a pressure canner, from our US Department of Agriculture. 

USDA Guide to Home Canning