Prep grapes: Remove grapes from stems, rinse under cold water, and discard any soft or damaged ones.
Dry completely: Pat grapes very dry with paper towels to help coating stick.
Lightly mist: Place grapes in ziplock bag or bowl, lightly spray with water just to make them tacky.
Make coating: In a separate bowl, mix jello powder, powdered sugar, and citric acid thoroughly.
Coat grapes: Add coating mix to the grapes bag. Seal and shake vigorously for about 30 seconds until fully coated.
Freeze: Spread coated grapes onto parchment-lined baking sheet, ensuring they don’t touch. Freeze for 4+ hours (overnight is best).