Arugula, known botanically as Eruca vesicaria or Eruca sativa, is a fast-growing, peppery leafy green belonging to the Brassicaceae family. Saving the seeds allows gardeners to preserve a favorite variety, ensure a supply for future plantings, and reduce the cost of buying new seed packets each season. This process requires patience after the plant has finished producing leaves, as the plant must be allowed to complete its annual life cycle and fully mature its reproductive structures. Understanding the timing of the plant’s transformation from leafy growth to seed production helps secure a bountiful harvest for the next growing year.
Recognizing Seed Pod Maturity
The journey to seed saving begins when the arugula plant “bolts,” sending up a tall, rigid flower stalk in response to warmer temperatures or longer daylight hours. Creamy white flowers appear along this stalk, attracting pollinators before fading. These flowers are replaced by slender, erect seed pods, technically called siliques, which are the containers for the developing seeds.
The seed pods transition from a soft, dark green to a pale tan or straw color, becoming papery and brittle as they dry out. This color change signals that the seeds inside are nearing maturity and hardening. When ready, the seeds should be dark brown or black, not a pale yellow or green. A rattling sound when the pods are lightly shaken indicates the seeds have fully dried and detached inside the silique.
Collecting the Seed Pods
Harvesting is best done when most of the pods on the stalk have turned tan, but before the driest ones begin to shatter and drop their seeds naturally. Arugula pods are notorious for shattering easily once fully dry, which can lead to significant seed loss. The ideal time for collection is on a dry, sunny morning after any dew has evaporated.
To minimize seed scatter, place a large bucket, tarp, or sheet beneath the plant before cutting. Using sharp pruners or scissors, cut the entire seed stalk at the base, near the main plant crown. Handle the brittle stalks with care, gathering them into a bundle. It is better to harvest the stalks slightly early and allow them to finish drying indoors than to wait too long and lose the seeds to the garden soil.
Drying and Separating the Seeds
After collection, the stalks require a secondary drying period to ensure the seeds are completely desiccated before storage. Bundle the cut stalks loosely and place them upside-down inside a large paper bag. Hang the bag in a cool, dry, and well-ventilated area for one to two weeks. The paper bag catches any seeds that drop as the remaining pods dry and naturally split open. The seeds are fully dry when they are too hard to dent with a fingernail.
The next step is threshing, the process of breaking open the dried pods to release the seeds. For large quantities, you can lay the stalks on a tarp and gently tread on them. For smaller batches, simply crush the dried pods by hand inside the paper bag or a container. The result will be a mixture of dark, round seeds and papery plant material known as chaff.
Winnowing is the final cleaning step, which separates the heavier seeds from the lightweight chaff. This is achieved by pouring the mixture from one container to another in front of a gentle, steady breeze, such as a light fan or natural outdoor air current. The breeze carries the lighter chaff away, while the heavier seeds fall straight into the lower container. Repeat this process until the seed sample is visibly clean, which is important for preventing mold and preserving viability in storage.
Storing Arugula Seeds
Proper storage is necessary to maintain the seed’s ability to germinate for future seasons. Arugula seeds, when stored correctly, can remain viable for an extended period, often retaining high germination rates for up to four to six years. The three primary requirements for successful long-term seed storage are cool temperatures, darkness, and low humidity.
Airtight containers, such as glass jars or sealed plastic bags, offer the best protection against moisture fluctuations and insects. Gardeners often include a small desiccant packet inside the container to absorb any residual moisture. The sealed container should then be kept in a cool, dark location, such as a refrigerator or a dedicated storage cabinet. Always label the container clearly with the seed variety and the date of harvest, as this information is necessary for tracking viability over the years.