Dark reactions of photosynthesis occur in

Dark reactions of photosynthesis occur in Stroma outside photosynthetic lamellae.
Dark reaction takes place in the stroma (aqueous fluid surrounding the stacks of thylakoids) and the cytoplasm.
The process requires NADPH, which is short-lived and comes from light-dependent reactions. In the dark, plants instead release sucrose into the phloem from their starch reserves to provide energy for the plant.