Growing new lavender plants from seed is a rewarding method of propagation, particularly if you aim to cultivate many plants or specific open-pollinated varieties. While cuttings clone a parent plant precisely, collecting seeds allows you to multiply your stock from the small, dark treasures hidden within the dried flowers. This process focuses on the physical steps needed to successfully harvest, clean, and store the seeds for future planting.
When Lavender Seeds are Ready to Collect
The optimal time for harvesting lavender seeds occurs after the flower spike has completely faded and the plant has finished blooming for the season. This period typically falls in late summer or early autumn, depending on your local climate and the lavender variety. Waiting for this progression ensures that the seeds inside have fully matured and hardened, which is necessary for viability.
The visual cue is the complete transformation of the flower spike from purple blossoms to a dried, papery structure. The calyxes—the small, cup-like structures that once held the petals—will have turned a dull tan, brown, or gray color and will feel brittle to the touch. The actual seed is housed within this dried calyx. If you gently tap the seed head, a few tiny, dark seeds may fall out, confirming they are ready. Harvesting too early results in immature seeds that will not germinate, while waiting too long risks the mature seeds naturally dropping to the ground.
Harvesting and Initial Drying of Seed Heads
Once the seed heads show signs of maturity, begin the physical harvest. Use sharp, clean scissors or snips to cut the flower stalk just below the cluster of dried seed heads, avoiding excessive shaking. Perform this task on a dry day, after the morning dew has evaporated, to prevent moisture from encouraging mold growth during the initial drying phase.
After cutting, gather the stalks into small, loose bundles and secure them with twine or a rubber band at the base. Hang these bundles upside down in a sheltered area that is cool, dry, and well-ventilated, such as a garden shed or attic. Allowing the seed heads to dry thoroughly for one to two weeks simplifies the extraction process and ensures the seeds are ready for long-term storage.
Extracting the Seeds from the Calyxes
The dried material is now ready for threshing, the process of separating the seeds from the surrounding plant matter. Lay the dried bundles over a clean, smooth surface, like a large tray, baking sheet, or fine-mesh screen. Gently rub the seed heads between your fingers or palms to crush the brittle calyxes and release the tiny seeds inside.
Alternatively, place the dried seed heads into a paper bag and gently shake or roll the bag to dislodge the contents. The lavender seed is very small, typically tear-shaped, and dark brown to black in color, often resembling coarse pepper. This mechanical action releases the seeds along with chaff, which is the term for the dried petals, stems, and broken calyx fragments.
The final step in extraction is winnowing, which cleans the seeds by removing the lightweight chaff. Pour the mixture of seeds and debris from one container to another in front of a gentle fan or outdoors on a slightly breezy day. The heavier seeds will drop straight down, while the lighter chaff will be blown away. For smaller batches, use a fine-mesh sieve to separate larger pieces of debris or pick out the remaining chaff by hand to ensure a clean seed collection.
Storing Seeds to Maintain Viability
Proper storage is necessary to maintain the integrity of the collected lavender seeds until the next planting season. Since seeds are living organisms in a state of dormancy, their viability is threatened by exposure to heat, light, and moisture. Storing them correctly prevents premature degradation and ensures a higher germination rate when you are ready to plant.
The best environment for seed storage is a cool, dark, and consistently dry location, such as a refrigerator or a cool cupboard. Use breathable containers like small paper envelopes or glass jars, which allow for a small amount of air exchange while keeping moisture out. Labeling the container with the specific lavender variety and the date of harvest is important for tracking viability over time.