Arugula is a popular, peppery salad green and a cool-weather annual plant. As temperatures rise, the plant bolts, sending up a tall stalk that develops small, white flowers. After flowering, the plant produces seed pods, offering gardeners an opportunity to save seeds. Understanding the precise timing and collection methods is key to securing next season’s crop.
Identifying Mature Seed Pods and Harvesting
After the small, four-petaled white flowers fade, the plant forms long, thin seed pods, known as siliques. Initially, these pods are green and soft, indicating the seeds inside are immature. Harvesting should only occur once the siliques transition from green to a light tan or straw-brown color, signaling that the seeds have fully matured and dried sufficiently on the plant.
The optimal time for collection is when the plant is dry, but before the pods become brittle and shatter, causing significant seed loss. Rather than picking individual pods, cut the entire seed stalk near the base of the plant. Place the cut stalks, head-first, into a large paper bag or bucket to capture any seeds that drop during transport.
Extracting and Cleaning the Seeds
The collected seed stalks require a period of final drying to ensure maximum seed longevity. Hang the stalks upside down in a warm, dry, and well-ventilated location for one to two weeks. This extended drying time eliminates remaining moisture within the pods or seeds, which prevents mold during storage.
Once the material is completely brittle, release the small, dark brown seeds from their casings. Place the dried stalks inside a container or cloth bag and crush the brittle pods by hand or with a rolling pin to break them open. This creates a mixture of seeds and dried pod material known as chaff, which must be removed for proper storage.
Separating the seeds from the chaff is achieved through winnowing or careful sifting. Winnowing involves gently pouring the mixture from one container to another in front of a light breeze or a slow-speed fan. The lighter chaff is blown away, while the heavier seeds drop straight down into the receiving container. Seeds must be completely dry and free of debris before moving them to permanent storage.
Storing Seeds for Long-Term Viability
Arugula seed viability is maintained by storing them in cool, dark, and dry conditions. Humidity is the greatest threat to longevity, as moisture can trigger premature germination or fungal growth, even in small amounts. A temperature consistently below 50°F (10°C) is ideal for slowing the metabolic rate of the seed embryo.
Airtight options like glass jars or sealed plastic bags offer the best protection against external moisture and pests. Seeds must be absolutely dry before being sealed in glass, as trapped moisture rapidly leads to spoilage. Small paper envelopes are suitable, provided they are placed inside a larger, airtight container to protect them from environmental humidity.
Proper labeling is necessary, requiring the inclusion of the seed type and the date of harvest. Storing seeds in a stable environment, such as a refrigerator or a cool pantry, prevents temperature and humidity fluctuations that degrade quality. Arugula seeds maintain high germination rates for three to five years when stored correctly, offering several seasons of use.