Nasturtiums are vibrant annuals, celebrated for their bright, edible flowers and peppery leaves. Saving the seeds is an excellent way to ensure a continuous supply for future seasons, allowing you to propagate favorite varieties and save the expense of purchasing new seeds. This process is remarkably straightforward, offering a simple method to preserve the genetic material of your strongest plants.
Identifying Mature Seeds
The timing of collection is crucial, as immature seeds will not germinate reliably. Seeds develop within small, round pods located near the base of the flower after the petals have fallen off. Initially, these pods are plump, firm, and bright green, but they must be allowed to ripen on the vine until they change color.
A mature seed pod transitions from green to a pale yellow, tan, or light brown hue, indicating the embryo inside has fully developed. They are typically wrinkled, about the size of a large pea, and often appear in clusters. The most reliable test for maturity is tactile: a ripe seed pod will detach from the plant with a gentle touch or light twist, signaling it is ready to drop. If you have to pull or tug, the seed is still immature and should be left for a few more days to finish ripening.
The Collection Process
Mature nasturtium seeds tend to drop naturally to the soil once they are fully ripened, which simplifies the collection process. One of the easiest ways to gather them is to gently move the surrounding foliage and inspect the ground directly beneath the plant. You will often find the characteristic wrinkled, tan-colored seeds lying on the soil surface, especially in late summer or early autumn.
Alternatively, collect the pods directly from the plant, selecting only those that are visibly tan or brown and fall off easily. Use a small basket or a paper bag for collection, as this allows for air circulation and prevents moisture from being trapped. Collecting on a dry, sunny day is best, as seeds that have recently been rained on or are sitting in wet soil can begin to disintegrate.
Drying and Curing the Seeds
After collection, the seeds must be thoroughly dried, or cured, before long-term storage to prevent mold or rot. This step ensures all internal moisture is removed, even from seeds collected dry from the ground. Spread the collected seeds in a single layer on a paper towel, a paper plate, or a fine mesh screen.
Place the drying surface in a cool, dry, and dark location away from direct sunlight, such as an airy room. The curing process takes time, often ranging from one to three weeks, depending on the initial moisture content. A seed is completely dry when it feels rock-hard, has fully shriveled, and turned a consistent tan or brown color. Turning the seeds over every few days promotes even air circulation and quicker drying.
Storing for Future Planting
Proper storage conditions are necessary to maintain the viability of nasturtium seeds until the next planting season. Once the seeds are completely dry and hard, transfer them into paper envelopes or small paper bags, which allow for air exchange. Each package should be clearly labeled with the variety name and the year of collection to track the seed’s age.
Place these labeled paper packages inside a larger, airtight container, such as a glass jar or sealed plastic box, to protect them from pests and fluctuations in humidity. The ideal storage location is a cool, dark place with stable temperatures, such as a basement or a refrigerator crisper drawer. Under these consistent conditions, nasturtium seeds can remain viable for up to three years.