Growing an elderberry bush (Sambucus) from seed is a rewarding project that allows the gardener to participate in the full life cycle of this useful plant. Elderberries are valued for their clusters of dark purple fruit, which are commonly used in jams, syrups, and beverages, and are recognized for their high levels of antioxidants. Successfully germinating an elderberry seed requires patience and a specific understanding of its natural biology, as the seeds employ a complex defense mechanism against premature sprouting. The seed possesses a deep-seated dormancy that must be overcome by mimicking two seasons of natural weather cycles.
Seed Collection and Preparation
Obtain high-quality seeds by purchasing them or harvesting them from ripe, dark purple elderberry fruit. The most important initial step is the complete removal of the fleshy fruit pulp, which contains germination inhibitors that prevent the seed from sprouting.
To clean the seeds, mash the berries in a container with water. Viable, heavier seeds will sink to the bottom, while the pulp, skin, and empty seeds float to the surface. Pour off the floating debris and rinse the remaining seeds repeatedly until the water runs clear and all sticky residue is gone. After cleaning, allow the seeds to surface-dry for approximately 72 hours before proceeding.
Overcoming Dormancy: The Stratification Process
Elderberry seeds exhibit two types of dormancy: a hard seed coat that restricts water uptake and a dormant embryo requiring a chilling period. To break this complex dormancy, the seeds require double stratification, a two-stage process simulating the natural progression of warm and cold seasons.
The first stage is warm stratification, which softens the seed coat and prepares the embryo for growth. Mix the cleaned seeds with a sterile, moisture-retaining medium like damp sand, peat moss, or vermiculite. The medium should be moist but not saturated. Place this mixture into a sealed plastic bag and store it at a warm temperature, ideally around 75°F (24°C), for 60 days. This warm phase improves overall germination rates.
After the warm period, the seeds must immediately transition to the second, longer stage: cold stratification. Move the bag of seeds and medium to a refrigerator and store it between 35°F and 40°F (2°C and 4°C). This 90-day chilling period mimics the winter environment. Check the seeds periodically to ensure the medium remains damp and that no mold has formed.
Sowing and Initial Care
Once the cold stratification period is complete, the seeds are ready for sowing, typically timed for early spring. Use a sterile seed-starting mix in shallow trays or pots to prevent the introduction of pathogens. Sow the seeds very shallowly, covering them with only about one-quarter inch (0.6 cm) of soil.
Place the containers in a location that receives bright, indirect light and maintains a consistent temperature. The soil must be kept evenly moist but never waterlogged, as this is a common cause of failure for young seedlings. Even with successful stratification, elderberry seeds can take several weeks or months to sprout, so ongoing patience is required.
Transplanting and Establishment
When the seedlings have developed their second set of true leaves and appear stable, move them into individual pots for continued growth. Before moving the young plants to their final outdoor location, they must undergo a hardening off process. This gradually acclimates them to sun, wind, and temperature fluctuations by placing them outside in a sheltered spot for increasingly longer periods over one to two weeks.
Elderberry plants grow best in full sunlight, which encourages the highest fruit yield, though they tolerate partial shade. The chosen site should have moist, well-drained soil with a slightly acidic pH, ideally between 5.5 and 6.5. Space the seedlings approximately six to eight feet apart to allow for mature growth and good air circulation.
During the entire first year, consistent watering is necessary. Apply a layer of mulch around the base of the plant to help retain soil moisture and suppress competing weeds, which is important due to the plant’s shallow root system.