Prepare the Grape Juice

1. Wash and Crush Grapes: Thoroughly wash the muscadine grapes and remove any stems. Place the grapes in a large pot and crush them using a potato masher or your hands to release the juice.
2. Cook the Grapes: Add 1 cup of water to the pot with the crushed grapes. Bring to a boil over medium heat, then reduce the heat and simmer for 10-15 minutes until the grapes are soft and the skins have burst.
3. Strain the Juice: Pour the cooked grape mixture through a jelly strainer or cheesecloth into a large bowl, allowing the juice to drain. Press the solids gently to extract more juice, but avoid squeezing too hard to keep the juice clear.

Make the Jelly

4. Measure the Juice: Measure 5 cups of grape juice. If you have less than 5 cups, add water to make up the difference.
5. Combine Juice and Pectin: In a large pot, combine the grape juice, powdered fruit pectin, and lemon juice. Stir well to dissolve the pectin.
6. Bring to a Boil: Bring the mixture to a rolling boil over high heat, stirring constantly.
7. Add Sugar: Add the granulated sugar all at once. Stirring constantly, return the mixture to a full rolling boil that cannot be stirred down.
8. Boil the Jelly: Boil for 1-2 minutes, continuing to stir, until the jelly reaches the desired consistency. Use a candy thermometer to check if the jelly reaches 220°F, or use the spoon test to check for gel consistency.

Process the Jelly

9. Skim Foam: Remove the pot from heat and skim off any foam from the surface of the jelly using a metal spoon.
10. Fill Jars: Ladle the hot jelly into sterilized jars, leaving 1/4 inch of headspace. Wipe the rims clean with a damp cloth and seal with sterilized lids and rings.
11. Process in Water Bath: Process the jars in a boiling water bath for 10 minutes to ensure they are sealed properly.
12. Cool and Store: Remove the jars from the water bath and let them cool on a towel or wire rack. Check seals after 24 hours. Store in a cool, dark place for up to a year.