Tomatillos, often mistaken for a type of green tomato, belong to the Solanaceae family, making them relatives of peppers and eggplant. They are botanically distinct from tomatoes, yet they share a similar fruit structure that requires specific handling for seed retrieval. Saving seeds from successful plants ensures a supply for the next season and helps preserve desired traits for future crops. This process involves careful fruit selection, a unique extraction technique, and proper preparation for long-term dormancy.
Identifying Ideal Fruits for Seed Saving
Selecting the parent fruit is the first step in ensuring the genetic quality of next year’s crop. Gardeners should prioritize plants that exhibited the most vigor, resistance to disease, and produced the highest yield of desirable fruit. Save seeds only from open-pollinated varieties (heirlooms), as hybrid seeds often do not reliably reproduce the parent’s characteristics. Choosing fruits from multiple healthy plants also helps maintain genetic diversity and plant robustness in the following season.
The fruit selected for seed saving must be allowed to fully mature past the point of culinary readiness. Leave the tomatillos on the plant until the outer papery husk begins to dry out, turn brown, and often splits open. This overripe stage ensures the seeds inside have reached full physiological maturity, maximizing their germination potential.
Extraction and Fermentation Process
Once the mature fruits are harvested, the seeds must be separated from the surrounding pulp, a step complicated by the sticky, gelatinous matrix encasing each seed. This coating contains germination inhibitors that must be neutralized before the seeds can be successfully dried and stored. The most reliable method to achieve this is through a controlled wet processing technique, which often involves fermentation.
Start by removing the fruit from the husk and crushing the pulp directly into a glass jar or non-metallic container. Add an equal volume of water to the crushed pulp, mixing gently to ensure the material is submerged. The container should be covered loosely with cheesecloth or a lid that allows air exchange, preventing the build-up of fermentation gases.
This mixture is allowed to sit at room temperature, typically between two and four days, during which time a layer of mold or scum will often form on the surface. The fermentation process breaks down the gelatinous coating, which frees the viable seeds to sink to the bottom of the container. This process also helps eliminate certain seed-borne diseases and improves overall germination rates.
After the fermentation period is complete, carefully pour off the water, mold, and floating debris. The heavier, viable seeds remaining at the bottom must then be thoroughly rinsed with clean water. Multiple rinses remove all traces of the fermentation residue and pulp, preparing the seeds for the final drying stage.
Ensuring Complete Seed Drying
After the final rinse, the clean seeds must be spread out immediately onto a non-stick surface, such as a ceramic plate, a sheet of glass, or a coffee filter. This step is necessary to maintain seed viability during storage and prevent mold growth. Avoid using standard paper towels, as the seeds will strongly adhere to the material as they dry.
The seeds should be spread thinly in a single layer to maximize exposure to air and promote even drying. This process should occur in a well-ventilated location, away from direct sunlight or any source of high heat, which can damage the delicate embryonic tissue inside the seed. Research suggests that drying temperatures between 30 and 35 degrees Celsius allow the seeds to express their maximum physiological quality.
The drying period typically ranges from one to three weeks, depending on ambient humidity and temperature. A simple test for complete dryness is to attempt to bend a seed; a fully dry seed will snap or break cleanly rather than bending or squishing. Any remaining moisture significantly reduces the seed’s lifespan and increases the risk of fungal contamination in storage.
Proper Long-Term Storage
Once the tomatillo seeds are completely dry, they require an optimal environment for long-term dormancy. The goal of storage is to protect the seeds from the three primary threats to viability: moisture, heat, and light. Fluctuations in temperature and humidity are particularly damaging, as they can trigger premature metabolic activity and reduce longevity.
The ideal storage location is consistently cool, dark, and dry, such as a refrigerator or a climate-controlled cabinet. Seeds can be packaged in small paper envelopes or breathable bags, which help manage any slight residual moisture by allowing it to dissipate slowly. For maximum protection against humidity, the envelopes should be sealed inside an airtight glass jar or a durable, sealed plastic container.
Before sealing the containers, it is necessary to label them clearly and permanently with the variety name and the exact date the seeds were saved. Labeling ensures the gardener knows the age of the seeds and can prioritize using older stock. When stored correctly in these cool and dry conditions, tomatillo seeds typically maintain high germination rates for four to six years.