Raspberry seeds need a period of cold-moist stratification to break their dormancy and trigger germination. The simplest way to achieve this is to simulate natural winter conditions by storing the seeds in a moist medium in your refrigerator. Pre-soak the seeds: Soak the cleaned seeds in room temperature water for 24 hours to help soften their hard outer shell. Step-by-step indoor stratification Select a medium. For seeds, you can use a damp (not soaking wet) medium like peat moss, vermiculite,