A canning system for a jar is described. The system includes a plunger configured to translate through a neck of the jar. A seal is in communication with the plunger and configured to flex its shape so as to conform to the size of the jar as it passes through the neck. The seal extending beyond the periphery of the plunger. A rod is configured to engage the plunger and selectively locate the position of the plunger within the jar. An optional cap may be used to assist in locating the plunger in the jar prior to sealing the jar with a lid.