Yellow rocket is a biennial herb endemic to Europe. Saint Barbara, the patron saint of artillerymen and mining workers, inspired the name Barbarea. This plant’s leaves are edible, whether raw or cooked. It also has a natural resistance to several bug species.
I. Appearance and Characteristics
Barbarea vulgaris, also called wintercress (usual common name), or alternatively winter rocket, rocketcress, yellow rocketcress, yellow rocket, wound rocket, herb barbara, creases, or creasy greens, is a biennial herb of the genus Barbarea, belonging to the family Brassicaceae. Native to Eurasia and North Africa, it is naturalised in many parts of North America and New Zealand as a weed.
The genus name Barbarea derives from Saint Barbara, the patron saint of artillerymen and miners, as this plant in the past was used to soothe the wounds caused by explosions. The species Latin name vulgaris means “common”.
This plant grows to about 30–60 cm (12–24 in) high, with a maximum of 1 m (3 ft 3 in). The stem is ribbed and hairless, branched at the base. It has basal rosettes of shiny, dark green leaves. The basal leaves are stalked and lyre-pinnatifid, that is with a large terminal lobe and smaller lower lobes. The cauline leaves are smaller, ovate, toothed, or lobed. The flowers are borne in spring in dense terminal clusters above the foliage. They are 7–9 mm (0.28–0.35 in) long, with four bright yellow petals. The flowering period extends from about April through July. The fruit is a pod around 15–30 mm (0.59–1.18 in).
Chemical substances in this species include saponins, flavonoids, and glucosinolates.
Natural insect resistance and its potential use in agriculture
Most B. vulgaris genotypes are naturally resistant to some insect species that are otherwise specialized on the crucifer family. In the case of diamondback moth (Plutella xylostella) and the flea beetle Phyllotreta nemorum, the resistance is caused by saponins. Glucosinolates such as glucobarbarin and glucobrassicin are used as a cue for egg-laying by female cabbage white butterflies such as Pieris rapae. Indeed, the larvae of this butterfly thrive well on this plant. Diamondback moth females are also stimulated by these chemicals, but the larvae die due to the content of saponins which are apparently not sensed by the moths. This phenomenon has been tested for biological insect control: B. vulgaris plants are placed in a field and attract much of the diamondback moth egg load. As the larvae die shortly after hatching, this kind of insect control has been named “dead-end trap cropping”.
The plant prefers fresh or moist places, on roadsides, along rivers, in arable land, wastelands and docklands, or on the slopes and in ditches, at an altitude of 0–2,500 m (0–8,202 ft) above sea level.
It also prefers to grow in siliceous, calcareous, sandy, alluvial and clay soils.
II. How to Grow and Care
Yellow rocket is characterized by a relatively undemanding care regimen, suitable for gardeners of varying experiences. Yellow rocket is resilient to cold temperatures and can usually tolerate a range of soil types, handling periods of neglect without serious consequences. Special care points include ensuring adequate moisture during dry spells and the occasional need for controlling its spread, as yellow rocket can exhibit invasive tendencies if left unchecked.
Sunlight
Yellow rocket thrives best in conditions of full sun where it can receive unfiltered, direct sunlight for at least six hours a day. While it has a tolerance for partial sun, meaning it can still grow with less than optimal sun exposure, its growth and health may not be as robust. In partial shade, yellow rocket is likely to exhibit reduced flowering and a leggier growth habit as it reaches for light. Without sufficient light, yellow rocket may also show signs of weakened vigor and paler leaves. Ideally, when planted outdoors, yellow rocket should be positioned in a spot where it can enjoy the sun’s rays most of the day, away from taller plantings that may cast excessive shade.
Watering
Yellow rocket thrives in moist environments, reflecting its native habitat’s abundant water availability. It exhibits a preference for consistent moisture but can tolerate brief periods of dryness. Watering should be done every week to maintain its hydration needs. Yellow rocket is typically grown outdoors and has a remarkable ability to adapt to varying rain patterns, which influences its resilience during the growing season.
Propagation
Yellow rocket is best propagated by sowing seeds in Spring, as it does not raise complications. Signs of successful propagation include sprouting leaves and steady growth. Ensure ample sunlight, drainage, and consistent moisture for optimal results.
Transplanting
The best time to transplant yellow rocket is during its second to third growth season, as it allows sufficient time for the plant to establish. It prefers sun or partial shade locations, with moist soil. Remember, regular watering post-transplant leads to healthy growth.
III. Uses and Benefits
- Ornamental uses
Yellow rocket is a tall wildflower that will look good at the base of hedgerows and in woodland gardens. When planted in a garden, it will grow throughout mild winters, attracting bees as it blooms in the late spring and summer. However, this plant can easily become invasive.
- Culinary uses
The young leaves can be eaten raw or cooked. The buds and flowers are also edible.
- Other uses
It can also be used as a dead-end trap crop for diamondback moth, the caterpillar of which is a pest on cruciferous plants like Cabbage.
