Ground cherries are close relatives of tomatoes and tomatillos, offering a unique, sweet-tart flavor often described as a mix of pineapple, vanilla, and strawberry. These fruits, typically Physalis pruinosa, grow encased in a distinctive papery husk or calyx. Saving the seeds from your best plants preserves the variety and ensures a continuous supply of this unusual fruit without recurring costs. The process involves careful selection, a specific cleaning method called fermentation, and proper drying to maintain the seeds’ viability for future seasons.
Selecting Ground Cherries for Seed Saving
Choosing the right fruit is the foundational step in successful seed saving. The ground cherry fruit must be fully mature, which is signaled by the papery husk turning completely dry, brittle, and brown. Unlike many fruits, ground cherries are typically ready for harvest only after they have naturally dropped from the plant to the ground.
Select fruit only from plants that exhibited strong growth, high yield, and resistance to common diseases throughout the season. Selecting from superior parent plants helps ensure that desirable genetic traits are passed on to the next generation. Once collected, the ripe fruits can be stored in their husks in a cool, dry place for several weeks, allowing the seeds to fully mature before processing.
Fermentation: The Seed Cleaning Process
Ground cherry seeds, like those of their tomato relatives, are encased in a gelatinous sac that contains germination inhibitors. This coating must be removed for optimal storage and sprouting. The process of fermentation is designed to break down this sticky coating, separating the viable seeds from the fruit pulp and any immature seeds.
To begin, remove the dry husks and slice the ground cherries in half to expose the pulp and seeds. Squeeze or scoop the pulp and seeds into a small, non-metallic container, such as a jar or bowl. Add a small amount of water, roughly equal to the amount of pulp, to create the environment for fermentation.
The container should be covered loosely—for example, with cheesecloth or a paper towel secured with a rubber band—to allow air exchange while preventing contamination. Place the mixture in a warm location, ideally around room temperature, and allow it to sit for two to four days. During this period, naturally occurring microorganisms will consume the gelatinous coating.
Stir the mixture gently once a day to ensure all the seeds are exposed to the process. As the fermentation progresses, a layer of mold or scum may form on the surface, which is a normal sign that the process is working. The fermentation is complete when the viable seeds have separated from the pulp and sunk to the bottom of the container. Immature seeds and lighter pulp will continue to float on the surface.
Carefully pour off the water, the surface mold, and the floating pulp and seeds, leaving the sunken seeds at the bottom. Refill the container with clean water and stir again to further separate any clinging pulp. The heavy, viable seeds will quickly sink again, allowing you to pour off the remaining debris. Repeat this rinsing process several times until the water remains clear and only clean seeds are left.
Proper Drying and Long-Term Storage
Once the fermentation and rinsing process is complete, the clean seeds must be thoroughly dried before storage to prevent mold and preserve their viability. Transfer the seeds from the water bath into a fine-mesh strainer to drain the excess moisture. Avoid using paper towels, as the small seeds will stick firmly to the paper fibers once they dry.
Spread the clean seeds in a single, thin layer onto a non-porous surface, such as a ceramic plate, a glass dish, or a fine screen. Place the plate in a cool, dry area away from direct sunlight and circulating air. The drying process typically takes one to two weeks, depending on the humidity of the environment. The seeds are fully dry when they are rock-hard and cannot be dented with a fingernail.
Once dry, transfer the seeds to an airtight container, such as a small glass jar or a sealed paper envelope. Labeling the container with the variety name and harvest date is important for tracking inventory. Ground cherry seeds can remain viable for four to six years when stored in a consistently cool, dry, and dark location.