Stratification

• Unlike seeds from plants like tomatoes or lettuce that germinate readily when they receive enough water and warmth, raspberry seeds must go through a dormancy period before they can sprout. Even if the seed encounters perfect growing conditions, it won't come out of dormancy before going through an extended period of cold temperatures. This process is called stratification.
  
  

Scarification

• To germinate raspberries, the seeds' hard outer shell must weakened enough for the plant embryo to be able to sprout. This occurs in nature when the seeds pass through the digestive system of birds or animals that eat the berries, or when seeds undergo extremes in temperature. This process is called scarification.
  
  

Grow Raspberries from Seed

• Raspberry seeds are available commercially that have already been stratified and scarified and are ready to plant. You can also try to grow raspberries from berries. In August or September, rub the pulp off a few raspberries and clean the seeds thoroughly. Leave the seeds out to dry in the sun. Next, cover the seeds in a pot with an inch of compost and put in a very cool area, out of sunlight. Keep soil moist, but not wet, to prevent rot. When seedlings appear in late winter, move them to a cold frame and then out to the garden after danger of killing frost. Another technique is to soak the seeds for a day in a mixture of half hydrogen peroxide and half water to scarify them. Next, put them in the refrigerator in damp medium for 90 days to stratify before potting the seeds.
  
  

Grocery Store Seeds

• Raspberries sold at grocery stores are usually grown from sterile seeds and will not germinate. Even if the seeds are not sterile, the fruit probably has been picked while too immature for seeds to sprout.