Asparagus is a highly valued perennial vegetable that returns year after year, providing some of the earliest harvests in the spring. Saving seed from established plants offers a pathway to propagation and the development of strains adapted to local growing conditions. This guide details the process, from identifying the correct parent plants to preparing and storing the seeds for future planting.
Identifying Seed-Bearing Plants and Timing the Harvest
Asparagus is a dioecious plant, meaning individual plants are either male or female. This distinction is fundamental to seed saving because only female plants produce the fruit that contains the seeds. Male plants focus their energy entirely on spear production, often resulting in higher yields. Female plants are easily identified in the late season because they develop small, round berries after flowering.
The berries are initially green but ripen to a bright orange-red color, typically in late summer or early fall. This color change is the visual marker of a seed-bearing female plant. To ensure the seeds are fully mature and viable, allow the berries to remain on the plant until they are fully colored and slightly shriveled. Harvesting at this stage indicates the embryo has reached maximum development.
Harvest usually occurs late in the season, coinciding with the browning and dieback of the fern-like foliage. Gently pluck the berries by hand or snip small sections of the fern holding the fruit clusters. Collecting fully ripe berries before they drop ensures maximum seed viability. Note that asparagus berries are mildly toxic and should not be consumed.
Extracting Seeds from Asparagus Berries
Once the mature berries are collected, the seeds must be separated from the fleshy pulp and gelatinous coating through wet processing. This method is necessary because the pulp often contains germination inhibitors. Begin by placing the berries in a container and thoroughly crushing them to expose the seeds.
Add water to the crushed berries and vigorously stir the mixture, a process called maceration. The goal is to separate the viable, heavy seeds from the lighter pulp and non-viable, floating seeds. The heavier seeds will sink to the bottom of the container, while the pulp and light, undeveloped seeds will float.
Allowing the mixture to sit for two to three days initiates a mild fermentation, which helps break down the pulp more effectively. After this period, carefully pour off the water, pulp, and floating debris, ensuring the sunken seeds remain. Repeat this rinsing and decanting process until the remaining water is mostly clear.
The clean seeds left at the bottom should be hard, round, and dark black, indicating they are fully developed and viable. Transfer these seeds onto a fine mesh screen or a plate to begin drying. Discard any remaining pulp or light-colored seeds.
Drying and Storing Asparagus Seeds
Thorough drying is necessary to halt physiological processes within the seed and prevent mold or rot during storage. Spread the newly cleaned seeds in a thin, single layer on a non-porous surface, such as a ceramic plate or a fine screen. Avoid using paper towels, as the wet seeds can stick firmly to the paper.
Place the seeds in a cool, dark, and well-ventilated location, away from direct sunlight or high humidity. The drying period typically takes one to three weeks, depending on ambient conditions. The seeds are sufficiently dry when they feel hard and brittle, resisting any attempt to dent or bend them.
Once fully dry, the seeds are ready for long-term storage to maintain viability. Label an airtight container, such as a glass jar or a small paper envelope, with the asparagus variety and the date of harvest. Labeling the container prevents confusion and ensures proper rotation of the seed stock.
Place the sealed containers in a cool, dark location where the temperature remains consistent, such as a refrigerator or a root cellar. Properly dried and stored seeds can remain viable for three to five years. Planting the saved seed within the first few years provides the best chance for successful germination.