The blackberry (Rubus spp.) is a type of perennial fruit-producing shrub related to raspberries. The shrub produces flowers once a year that turn into fruit within one to two months. The plants can be grown in all types of soil and can be started from seeds from existing blackberry fruit. Wash and dry the fruit seeds to prepare them for storage or planting directly into a pot or the ground.
Place the blackberry fruit into a mesh-bottom kitchen strainer. Place the kitchen strainer under cool, running water.
Smash the fruit with your fingers, turning the blackberry into a dark mush. Stir the matter with your fingers to separate the small, white seeds from the fruit itself. Rinse away the fruit flesh until mostly seeds remain.
Pick up each seed and run it between your fingers under the water to get rid of any remaining fruit particles. Place the seeds onto a paper towel on a plate or in a bowl.
Press another paper towel on top of the seeds to squeeze out excess water. Remove the top paper towel and set the plate or bowl aside.
Place the bowl or plate in a dry area and let it sit for 72 hours. Speed up the drying process by directing an optional room fan at the plate or bowl.
Empty the dried blackberry seeds into an airtight container and store the container in a cool, dry and dark place until you are ready to plant the blackberry seeds.