Arugula, often called rocket or roquette, is a popular salad green prized for its distinctive pungent, peppery flavor. This plant has successfully transitioned from an ancient Mediterranean herb to a celebrated feature in modern cuisine worldwide. Many gardeners remain confused about whether arugula is a cultivated crop or a wild weed. This dilemma stems from the plant’s robust growth habits, which blur the line between a sown plant and an aggressive volunteer. The answer lies in how humans define a weed.
The Botanical Classification of Arugula
From a scientific standpoint, arugula is a cultivated crop, not a wild weed species. It belongs to the large Brassicaceae family (mustard or cabbage family), which includes familiar vegetables such as broccoli, cauliflower, and kale. The common garden variety, Eruca vesicaria (or Eruca sativa), is an annual herb. It originated in the Mediterranean region and Western Asia, where it was domesticated centuries ago. As an annual, its life cycle is completed within a single growing season, contrasting with perennial weeds. Arugula is propagated by seed specifically for human consumption, classifying it as an intentionally grown food plant.
The Contextual Definition of a Weed
The term “weed” is not a category recognized in botanical science; it is a subjective, human-centric label. A plant is considered a weed if it is growing where it is not wanted by the gardener or farmer. This definition depends wholly on context and the intent of the person managing the landscape. For instance, a corn stalk in a vegetable patch is a crop, but the same stalk sprouting unbidden in a soybean field is a weed. Weeds compete aggressively with intentionally grown plants for sunlight, water, and nutrients. This contextual viewpoint explains why a plant can be both a crop and an unwanted weed simultaneously. The classification depends entirely on whether it was sown by intention or if it appeared spontaneously.
Why Arugula Appears to Be a Weed in the Garden
Arugula’s aggressive life cycle is the primary reason it often acts like a weed in the garden. It is a fast-growing cool-season annual, capable of germinating and producing harvestable leaves in as little as four to six weeks. This rapid maturity is a trait commonly shared with many successful weed species.
The plant is also highly sensitive to heat, which triggers bolting. Once temperatures rise, the plant rapidly sends up a flower stalk, diverting energy from leaf production to reproduction. The flowers are followed by slender seed pods, or siliques, which contain many small, viable seeds.
If a gardener fails to harvest the plants before bolting and subsequent seed drop, the arugula will aggressively self-seed. The seeds fall directly onto the soil, where they can survive the winter and germinate the following spring, often popping up in unexpected places. These spontaneous seedlings are known as “volunteer plants.”
These volunteers are technically the offspring of a cultivated crop, but because they are growing in an undesired location and competing with planned plantings, they fit the practical definition of a weed. Managing this self-seeding tendency requires gardeners to pull bolted plants before the siliques dry and shatter. By understanding that arugula is a crop with a weed’s survival instincts, a gardener can enjoy its peppery leaves while keeping its volunteer population under control.