Instructions for germinating and transplanting elderberry:
Elderberry seeds have a thick seed coat and natural dormancy, so they must be stratified to prompt germination. We’ve found that following the procedures below will provide the best results.
First prepare or buy a free draining soil to start your seeds, this can be a 50/50 mixture of compost and sharp sand, or perlite, vermiculite. We use the “potting mix” or “seed-starting mix” that is usually available at home improvement stores. The soil needs to be moist (but not wet), if you can squeeze water out of it with your hand it is too wet and your seeds may drown and die.
Place some of your seed starting soil into a zip-lock bag until it is about 1/3 full. Add the seeds into the soil, making sure to keep the seeds separated.
Write the date on the bag so that you know when the pre-treatment was started.
The seeds first require a period of warm pre-treatment and need to be kept at 68 degrees for a period of at least 10 weeks – it is not critical if it lasts a week or two longer than this.
I keep the bag on top of our furnace or water heater since these are the two spots in our home that stay warmer than 68 degrees during the winter.
During this time make sure that the pre-treatment medium does not dry out at any stage or it will be ineffective!
Next the seeds require a cold period to break the final part of the dormancy, this is easily achieved by placing the bag in the refrigerator for at least 14 weeks. You may start to see signs that the seeds are germinating in the bag. Some nurseries will go ahead and plant these early germinated seeds into a tray or pot.
When the period of pre treatment has finished the seed should be ready to be planted. Small quantities can be sown in pots or seed trays filled with a good quality compost and cover them with a thin layer of compost no more than 3/8″ deep.
We have used seed starting trays in the past but now only use 6″ or 8″ pots. Once the seeds have sprouted and grown to 3/4″ tall or more, we thin the extras out and plant them in their own pot. When the seedlings are 4″ tall or so, they are transplanted into the ground.