If you live at a high altitude, safely canning foods at home means you must adjust standard recipes based on your location. Altitude affects the processing times for water bath canning and the pressure requirements for pressure canning. Don’t let these factors intimidate you or discourage you from preserving at home: Whether you’re a novice or a pro, it’s easy to convert recipes based on your elevation.
How Altitude Affects Canning
According to the USDA, most cookbooks consider high altitude to be 3,000 feet above sea level, but you’ll need to make changes to canning recipes if you are as little as 1,000 feet above sea level. As elevation increases, the atmosphere is drier and there’s less oxygen and atmospheric pressure. The boiling point of water becomes lower, which means food takes longer to cook. More pressure is also required to reach the correct temperature for food safety. If you don’t correctly adjust for altitude by increasing processing times, increasing pressure settings, allowing canners to cool until depressurized and allowing jars to cool to room temperature, there is a good chance that your canned foods could spoil.
Water-Bath Canning Adjustments
Water boils at 212 degrees F at sea level, but boiling temperatures decrease by about 2 degrees for every 1,000 feet of elevation. This means your jars will be processed at a lower temperature requiring an increase in the amount of time they spend in the boiling water to remain safe for consumption.
“The rule of thumb is that if you’re over 1,000 feet in elevation, you increase the processing time by five minutes,” says Marisa McClellan, canning teacher and author of the cookbooks Food in Jars (Running Press, 2012) and Preserving by the Pint (Running Press, 2014). “Over 3,000 feet? Add another five minutes. By the time you get to 8,000 feet, you’re adding a full 20 minutes to your processing time.”
The guidelines below, based on recommendations from the University of Georgia National Center for Home Food Preservation, will help you convert a recipe so that you can successfully can it at higher altitudes. The time listed is the amount you should add to the processing time at sea level stated in the recipe.
- 1,001 to 3,000 feet: increase 5 minutes
- 3,001 to 6,000 feet: increase 10 minutes
- 6,001 to 8,000 feet: increase 15 minutes
- above 8,000 feet: increase 20 minutes
The National Center for Home Food Preservation uses hot-pack peaches as an example. A standard recipe for boiling-water bath canning for pints calls for a processing time of 20 minutes at sea level. If you live between 1,001 and 3,000 feet above sea level, the time increases to 25 minutes, then 30 minutes for elevations between 3,001 and 6,000 feet. Above 6,000 feet, the processing time is 35 minutes. When you plan out your day of canning, keep these times in mind, as they will require you to spend more time in the kitchen than your recipe might call for.
Pressure Canning Adjustments
Making altitude adjustments becomes increasingly important with pressure canning to destroy microorganisms in low-acid foods. You will need to increase canner pressure (PSI) and ensure that you cool the canner at room temperature until it is fully depressurized. The correct amount of steam pressure produces a temperature high enough to destroy bacteria: 240 degrees F. As elevation increases, so does the amount of canner pressure required to reach this temperature.
When using a dial-gauge pressure canner, 11 pounds of pressure is appropriate for elevations up to 2,000 feet. Beyond that, as a general rule, you will need to increase the pressure by about 1/2 pound per 1,000 feet of additional elevation. Use this guide.
- 2,001 to 4,000 feet: 12 pounds pressure
- 4,001 to 6,000 feet: 13 pounds pressure
- 6,001 to 8,000 feet: 14 pounds pressure
- 8,001 to 10,000 feet: 15 pounds pressure
If you are using a weighted-gauge pressure canner, use 10 pounds for up to 1,000 feet of elevation. For anything higher than 1,000 feet, use 15 pounds of pressure.
With these simple adjustments you can easily preserve your foods through water-bath or pressure canning regardless of where you live. For more help with home canning seek the advice of your local cooperative extension office or turn to accredited sources like the National Center for Home Food Preservation online.
Get more canning help from HobbyFarms.com:
- 9 Fixes for Canning Problems
- 8 Natural and Healthy Canning Substitutions
- 10 Must-Have Items for the Canner’s Pantry
- 6 Things Not to Do While Pressure Canning
- 9 Need-to-Know Tips for Canning Meat
About the Author: Lori Rice is a nutritionist, writer, recipe developer and author of The Everything Guide to Food Remedies (Adams Media, 2011). She shares her recipes, food photography and travel adventures on her blog, www.fakefoodfree.com.