Prepare a water bath canner, jars and lids before beginning.

If using lemon zest, start by zesting the lemons into the sugar. Stir and allow the mixture to sit for about an hour before proceeding. Remember that the lemon zest will need to be strained out before canning, and the easiest way to do that is to dissolve the sugar into the lemon juice and then strain the mixture before canning. (Zest is optional, but it adds amazing lemon flavor to the mixture. Use organic lemons if using the zest.)

Juice the lemons. Strain the juice to remove pulp and seeds and then measure the resulting juice. For every cup of lemon juice, add 1 cup of sugar. (If canning lemonade instead of concentrate, also add 6 cups of water.)

Gently warm the lemon juice and sugar mixture on the stove until it reaches around 190 F (do not boil).

Ladle the hot but not boiling lemonade mixture into prepared canning jars, leaving 1/4 inch headspace. Seal with 2 part canning lids to finger tight.

Half pints, pints, and quarts are processed for 10 minutes below 1,000 feet in elevation. 

Turn off the heat and leave the jars in the canner for an additional 5 minutes to cool slightly before removing them with a canning jar lifter to cool completely on a towel on the counter.

Wait 12 to 24 hours, then check seals. Store any unsealed jars in the refrigerator for immediate use. Properly canned and sealed jars may be stored in the pantry. Refrigerate after opening.