From Food in Jars:
- 6 cups pureed watermelon (remove any seeds prior to pureeing)
- 5 cups white sugar
- 4 6 tablespoons bottled lemon juice
- 1 packet powdered pectin
- Combine watermelon puree, sugar and lemon juice in a large, non-reactive pot.
- Bring to a boil and let cook until the temperature of the nascent jelly reaches 220 degrees.
- Add the powdered pectin and boil for another five minutes.
- Remove from the heat and pour into prepared jars.
Note: This jelly can take up to one week to set. Please give it time.