Remove berries from the bush during the autumn -- if possible -- and place in a bowl. Use your fingers to mash the berries into pulp. Sift through the pulp and remove the small hard seeds.
Use a mesh strainer to rinse away any excess pulp.
Put the seeds in a moist paper towel and place them indoors in a warm spot that's between 68 and 86 degrees Fahrenheit, such as near a heater vent or a windowsill that is not drafty.
Keep the paper towel moist and warm for about three months. Place the moist paper towel in your refrigerator -- between 36 and 41 degrees F -- for an additional 90 days, keeping the paper towel moist and replacing as necessary; this process mimics conditions that the seedling will experience after planting.
Plant the germinated seedling in the spring after the final frost of the season.