Rinse and sort chokecherries, removing stems and any debris.
Crush the cherries using a potato masher or a similar tool.
Place crushed cherries in a jelly bag or cheesecloth, allowing the juice to drip into a bowl. This may take a few hours.
Measure out 4 cups of chokecherry juice.
In a large saucepan, combine chokecherry juice, fruit pectin, and lemon juice. Bring to a boil over medium-high heat.
Stir in sugar, stirring constantly until dissolved.
Boil rapidly for 1-2 minutes until the jelly reaches the desired consistency.
Remove from heat and skim off any foam.
Ladle the hot jelly into sterilized jars, leaving a 1/4-inch headspace.
Wipe the jar rims, place the lids on, and process in a boiling water bath for 5-10 minutes.