2 cups watermelon juice (from about 1 small or 1/2 large watermelon)
3 tablespoons fresh or bottle lemon juice
3 1/2 cups granulated sugar
1 pouch Certo liquid pectin

To make watermelon juice, roughly chop watermelon. You’ll need about 6 cups of chopped melon to produce about two cups of juice. Run melon through a food mill (if you have one), or crush and then strain through a fine mesh sieve to remove any seeds or pulp. Prepare canner and wash/sterilize 8 4-ounce canning jars. Keep jars in hot (not boiling) water until ready to use. Combine watermelon juice, lemon juice, and sugar in a 6 to 8-quart nonreactive saucepan. Bring to a full roiling boil (a boil that doesn’t stop bubbling when stirred) over high heat, stirring constantly. Quickly stir in pectin. Return to a full rolling boil and boil exactly 1 minute, stirring constantly. Remove from heat. Skim off any foam with a metal spoon. Ladle hot jam into jars, leaving 1/4-inch of headspace. Wipe the rims clean and top with lid; screw on ring until finger tight. Process in a boiling water bath for 7 minutes. Remove from water and let cool completely, 12 to 24 hours. Check seals. Any unsealed jars should be refrigerated and used within 1 month. 6-7 4oz. Jars