The nasturtium (Tropaeolum majus) is an annual plant known for its vibrant, edible flowers and distinctive, peppery leaves. Gardeners appreciate its ease of growth and ability to thrive in various conditions. Saving nasturtium seeds from one season to the next is a straightforward, practical method to ensure a continuous supply of these plants without the recurring expense of buying new stock. This process allows you to perpetuate your favorite plant varieties in your own garden.
Recognizing When Nasturtium Seeds Are Ready
Identifying the correct time to harvest nasturtium seeds depends on the plant’s natural maturation cycle. The seeds must be allowed to fully ripen on the vine, indicated by their size and firmness. Initially, the seeds appear plump and green, but they are still soft and connected firmly to the stem at this stage.
As they reach maturity, the seeds transition in color, typically shifting from bright green to a pale yellow or creamy white hue. The texture changes from pliable to hard and firm, making them difficult to indent with a fingernail. Mature seeds naturally detach from the plant stem with only the slightest touch, often dropping onto the soil beneath the foliage.
Collecting and Cleaning the Seeds
The ideal time for collection is when the matured seeds have already fallen onto the ground or are only loosely attached to the plant. Nasturtium seeds typically form in clusters of three, resembling small, wrinkled peas. Gently gather these firm spheres from the soil or pluck them from the stem where they easily separate.
Once collected, the seeds require immediate cleaning to remove any remnants of the seed pod (chaff) or any slimy moisture adhering to the surface. Carefully rub off this residue, as organic matter and moisture can harbor pathogens and increase the risk of mold growth. Immediately after cleaning, the seeds must be spread out in a single layer to begin the drying process and prevent condensation from forming.
Essential Drying and Curing Steps
Proper drying, often referred to as curing, ensures seed viability over a long storage period. Curing involves reducing the internal moisture content of the seed to a safe level, typically below 10%, which halts metabolic processes and prevents fungal activity. To achieve this, spread the cleaned seeds in a single, uncrowded layer on a fine mesh screen or a paper plate to maximize airflow.
This setup promotes good airflow around each seed, which is more effective than drying them in a solid container. The seeds must be placed in a warm, dry location protected from direct sunlight, as intense heat can cause damage. This air-drying process usually requires two to four weeks, depending on the ambient humidity.
The drying process is complete only when the seeds are rock hard and cannot be dented or scratched by pressing a fingernail into the surface. Any residual softness indicates remaining moisture, which leads to seed failure or mold when placed into long-term storage. Thorough dehydration guarantees the seeds remain dormant until the next planting season.
Storing Seeds for Maximum Viability
Once the nasturtium seeds are dried, they are ready for long-term storage, which requires consistent environmental conditions. Before sealing them, label the container clearly with the date of harvest and the specific variety. This prevents confusion in future gardening seasons.
Airtight containers, such as small glass jars or sealed paper envelopes, are ideal for protecting the seeds from external moisture and pests. The optimal storage environment is cool, dark, and consistently dry, like the back of a closet or a dedicated space in a refrigerator. Fluctuations in temperature and humidity must be avoided, as these changes can prematurely signal the seeds to break dormancy or encourage fungal growth.