Wash and inspect six half-pint canning jars. For a processing time under 10 minutes, sterilize empty jars in boiling water for 10 minutes below 1,000 feet, adding 1 minute for each additional 1,000 feet of elevation. Keep jars hot until filling; a dishwasher wash alone is not sterilization for this short process. Prepare lids according to their manufacturer. Chill two small ceramic plates for checking the jam.

Blanch the peaches, 4-5 at a time, in a boiling water bath for about 1 minute. Remove with a slotted spoon, and immediately place in a large bowl of ice water. This will loosen the peach skins.

Remove the peaches from the ice water and drain. Cut the peaches in half, remove the pits, and remove the skins with a paring knife.

Cut the peaches into about half-inch chunks. You will need about 8 cups of chopped peaches.

Mash the peaches with a potato masher until you get the texture you want for your jam. You should have about 5 cups of mashed peaches. You can also use a food processor or immersion blender for a smoother mixture.

Mix the pectin, lemon juice, and ¼ cup sugar in a small bowl or measuring cup.

Place the peaches in a large cooking pot, and add the pectin mixture. Over medium high heat, bring everything to a full boil that does not go down when stirred. Stir the entire time so the jam does not burn.

Add the remaining sugar, stir well, and return the jam to a full rolling boil for one minute, stirring constantly. Remove from the heat. A spoonful on a cold plate gives an early indication of the texture, but the jam will continue setting as it cools. Do not add extra pectin at random; follow the pectin manufacturer’s tested directions for remaking a soft batch.

Skim off foam. Keep the jam hot for filling; gently stir to distribute the fruit. Have clean lids ready according to the lid manufacturer’s directions. Do not leave the jam to cool before packing it into hot jars.

Fill your jars, using the ladle and funnel, leaving 1/4 inch of clearance space at the top of the jar.

Wipe the rims of the jars with a clean, damp towel. Place the lids on the jars and secure with rings. Do not screw the rings on too tight.

For shelf-stable storage, use a tested peach-jam recipe matched to your specific low/no-sugar pectin, including its ingredient proportions, jar size, headspace and altitude-adjusted processing time. Pectin brands and package sizes are not interchangeable. Do not assume this older recipe’s generic box-or-tablespoon measure establishes a tested canning formula. If you cannot confirm a matching tested formula, cool promptly and refrigerate or freeze the jam instead of storing it in the pantry.

For jars processed using a matching tested canning formula, turn off the heat, remove the canner lid and wait 5 minutes before lifting the jars upright onto a towel. Cool undisturbed for 12–24 hours, then check seals and remove the bands. Refrigerate unsealed jars promptly. Label and store properly processed, sealed jars in a cool, dark, dry place; use within a year for best quality. Refrigerate after opening and discard the entire jar if mold or other spoilage appears.