Preparing canning jars is an important step in the process.
One of the very first steps in the canning process is preparing your equipment, including canning jars. Here’s how to go about prepping your jars for canning.
Inspect. Whether used or fresh out of a new box, inspect jars to make sure there are no knicks, chips, cracks, or large bubbles in the glass or debris inside the jars.
Wash. Canning jars – even brand new ones – should always be washed in hot soapy water and rinsed well (either by hand or in a dishwasher) just prior to use.
Sterilize (maybe). Steriling jars is only necessary if the food will be processed for less than 10 minutes. See our poster, How to Sterilize Canning Jars, for the step-by-step process.
Keep Hot. Keeping jars hot helps prevent breakage when filling the jars with hot food and then putting the jars into a hot canner for processing. The jars can be kept in a hot dishwasher or placed in a canner preheated to 140°F (for raw packed food) or 180°F (for hot packed food).
Fill. The general recommendation is to remove jars one at a time from wherever they’re being kept hot, to fill them with product and apply lids quickly, and to then place each jar once filled into the canner so that it remains hot.
For further information, visit the National Center for Home Food Preservation (NCHFP) or contact your local Cooperative Extension office
Brought to you by the UC Master Food Preservers of El Dorado County
Last updated July 2025