Elderberry seeds have a thick, tough seed coat and what botanists call “natural dormancy.” This means that the seeds must obtain optimal conditions before waking up from their deep sleep. In the case of elderberries, the seeds must be stratified twice.This is not difficult, but it takes time, up to seven months to complete. The stratification required to start propagating elderberry from seed should mimic nature’s cycle. First expose seeds to warm conditions– like the normal conditions found indoors– for several months. This is followed by winter temperatures for another three months. Experts suggest you mix the seeds into a well-draining substrate like a mixture of compost and sharp sand. This should be moist but not wet and there should be enough to keep the seeds apart from one another. Put the mixture and seeds into a large zip-lock bag and let it sit somewhere with temperatures of around 68 degrees F. (20 C.) for 10 to 12 weeks. After that, place it in the refrigerator at 39 degrees F. (4 C.) for 14 to 16 weeks. At this point the seeds can be sown in an outdoor seedbed, keep moist and wait for the seedlings to appear. After a year or two,move them to their final location.