Arugula (Eruca vesicaria or sativa), commonly known as rocket, is a popular, fast-growing leafy green cultivated globally for its distinct peppery flavor. While the leaves are the primary culinary focus, understanding the seed is necessary for successful propagation and appreciation of the plant’s life cycle. The tiny seeds are the source of new plants and are also used in other industries. Recognizing the specific characteristics of the seed is important for home gardeners and commercial growers.
Physical Description of Arugula Seeds
Arugula seeds are remarkably small, typically measuring between 1.5 and 2 millimeters in diameter. Their minute size makes them slightly smaller than most mustard seeds, to which they are often compared due to their similar botanical family. The shape is usually spherical or ovoid, meaning they are either perfectly round or slightly extended.
The color of the mature seed ranges from a pale brown to an olive-green shade. This coloration distinguishes them from the darker seeds of some other brassicas. The surface texture is not perfectly smooth but possesses a fine, slightly granular or rough quality.
The small dimensions and light weight are significant factors in handling and planting. Approximately 550 arugula seeds weigh only one gram, highlighting their compact nature. These physical attributes are consistent across the Eruca sativa species, whether used for planting or for oil pressing.
How Arugula Seeds Form on the Plant
Seed formation is the final stage in the plant’s reproductive cycle, triggered by bolting. Bolting occurs when the plant responds to high temperatures or long daylight hours by rapidly sending up a tall flower stalk. This shift diverts the plant’s energy away from producing leafy greens toward reproduction.
Small flowers, typically white or pale yellow with delicate purple veins, form at the top of this stalk. These flowers are self-pollinating or pollinated by insects, leading directly to the development of seed pods. The seed pods are slender, elongated structures known botanically as siliques.
Siliques initially appear as long, narrow green tubes. As the seeds mature inside, the siliques dry out, changing color from green to a light tan or brown. The small, spherical seeds are arranged in two or three rows within the silique. A mature, dried pod will often rattle when shaken, signaling that the seeds are fully ready for harvest.
Practical Uses and Storage
The primary use for arugula seeds is planting, and they are favored for their quick germination time. Seeds should be sown shallowly, about one-quarter inch deep, as they require light to break dormancy. Under ideal soil temperatures, germination can occur rapidly, often within five to ten days.
For a continuous harvest of greens, gardeners practice successive sowing, planting a new batch of seeds every few weeks during the cooler seasons. Beyond cultivation, the seeds can be pressed to yield arugula oil, which is valued for its unique flavor profile and high content of beneficial fatty acids. The young siliques themselves are also edible, offering a pungent, peppery taste.
For long-term storage, the seeds must be kept in conditions that preserve their viability. A cool, dark, and dry environment is necessary to prevent premature germination or degradation. When stored properly in an airtight container, arugula seeds can maintain high germination rates for up to six years.