Canning is not rocket science, but it is NOT the time to give your culinary creativity full rein. Keep it clean, follow the most current directions, and be sure to adjust canning times for your altitude. This article is your guide to high-altitude canning and safe home food preservation.
B is for Botulism, C is for Canning Safely
There. We said it. Botulism. The word that scares so many people away from home canning. According to the USDA, botulism is "an illness caused by eating toxin produced by growth of Clostridium botulinum bacteria in moist, low-acid food." The purpose of careful canning is to destroy such microorganisms in the food and allow you to store and eat it safely.
Some foods are naturally high in acid and can be safely canned using the hot water bath method (e.g., pickles, berries, peaches, salsa, and chutney). High sugar levels in jams and jellies also retard the growth of microorganisms. However, always check the pH of foods like tomatoes and figs as they may require acidification with lemon juice or citric acid to ensure safety. Use litmus paper to measure acidity, and adjust as needed.
High-Altitude Adjustments
Altitude affects boiling temperatures and, consequently, the effectiveness of canning methods. At higher altitudes, water boils at lower temperatures, requiring adjustments to processing times and pressure settings.
Hot Water Bath Canning
For hot water bath canning, increase processing time based on your altitude. Follow these guidelines from Colorado State University:
- If the sea level time is less than 20 minutes, add 1 minute per 1,000 feet above sea level.
- If the sea level time is more than 20 minutes, add 2 minutes per 1,000 feet.

Pressure Canning
Pressure canning requires increasing the pounds of pressure to achieve 240°F. Refer to the chart below for adjustments based on altitude:

Safe Canning Practices
Follow these safety tips to reduce the risk of botulism and ensure successful canning:
- Sterilize: Clean jars, lids, and tools thoroughly before use.
- Follow Tested Recipes: Use recipes from trusted sources like the USDA or the National Center for Home Food Preservation.
- Monitor Seals: Check jar seals after processing to ensure a proper vacuum.
- Discard Suspect Jars: If you suspect spoilage, discard the contents carefully, wearing gloves.
Tools for High-Altitude Canning
Get Started Today
In our video series, Tricia demonstrates how to can grape juice using a steam juicer and shows how to make and can applesauce. Follow her step-by-step tutorials to confidently preserve your harvest.
More Resources
For additional guidance, explore the National Center for Home Food Preservation or check out Preserving Food at Home, a trusted book for all your canning questions.