Juice 16-20 lemons and strain them to remove any pulp and seeds.
Puree six cups of fresh blueberries until smooth.
In a saucepan, gently heat the blueberry puree, lemon juice, and sugar until the sugar is completely dissolved. Heat the mixture to around 180 degrees, but make sure not to boil it. Stir well during this process to make sure the sugar and blueberry mix don't stick to the bottom of your pan.
When the mixture is perfectly heated and dissolved, fill your jars with hot blueberry lemonade concentrate, leaving a ΒΌ inch of headspace.
Seal the jars with your sanitized canning lids and load them into a water bath canner.
Process your pints in a water bath canner for 15 minutes (below 1,000 feet in elevation). Adjust the processing time based on the altitude, if needed.
After processing, leave the jars in the canner for an additional five minutes to cool slightly before using a canning jar lifter to remove them. Place them on a towel on the counter to cool completely.
After about 12 to 24 hours, check the seals of each jar. Any unsealed jars should be refrigerated for immediate use.
