an hour before filling them with your fresh, also boiling hot, jam. fill the jars all the way to the top, so as to leave just a small air pocket. put the lids on the jars right away. by the time the marmalade will have cooled off, the jars will be vacuum sealed and ready for winter storage in a cool dry place.
these very sour organic cherries from another neighbor made a delicious jam, but it needed some sugar. the peaches from the market needed just one spoon of sugar to soften them, because they were sweet on their own.
personally, i prefer to make another type of fruit jam, which 