A 15-20cm high annual herb with pale yellow to white flowers, wild radish grows in fallow fields, orchards, vineyards, roadsides and other disturbed habitats. Its young leaves and buds can be roasted or boiled and used in salads, stews, omelets and soups.
I. Appearance and Characteristics
Raphanus raphanistrum, also known as wild radish, white charlock or jointed charlock, is a flowering plant in the family Brassicaceae. The species is native to western Asia, Europe and parts of Northern Africa.
It was formally described by the Swedish botanist Carl Linnaeus in his seminal publication ‘Species Plantarum’ on page 669 in 1753.
Wild radish is an annual that grows up to 75 cm tall, variously branched to multi-stemmed, with a distinct slender taproot which does not swell like that of the cultivated radish. The stems are green and sometimes purple at the base and nodes, round in cross section and slightly ridged, and bristly-hairy all over. It has a basal rosette of pinnate leaves to 38 cm long, with a 3 cm stalk (petiole) and a large rounded terminal lobe that has an undulate margin; the lateral lobes sometimes overlap the midrib.
The stem leaves become progressively less lobed as they ascend, and more acutely serrated. Both the upper and lower surface of each leaf is roughly hairy, as are the leaf margins, which have minutely bulbous-based hairs projecting horizontally. The leaves have green or purple tips (hydathodes) on each tooth.
The flowering period is between May and October in northern Europe, or between June and August in Minnesota. The inflorescence is a lax raceme, terminal or arising from the leaf axil, up to 34 cm long with up to 42 flowers. The flowers have four white (sometimes yellow or purple) petals, up to 24 mm long, sometimes with dark veins (especially on the underside). Each petal has a rounded “limb” above a narrow “claw”, both about the same length. The four upright sepals are shorter than the petals, green or purple, and have sparse bulbous-based hairs. There are 6 stamens (2 short and 4 long) and one style with two stigmas.
The fruits are borne on bristly-hairy pedicels about 3 cm long and held vertically (whether the rhachis is erect or sprawling). Each fruit consists of a pod with two segments: the lower one is about 1-2 mm long and sterile (just occasionally with one seed), while the upper one is up to 8 cm long and has 1-10 fertile segments (mericarps), each containing one oval seed up to 3 mm long. At the tip of the pod is a sterile beak up to 2.5 cm long. The fruits are terete, smooth or slightly ridged, and glabrous to roughly hairy, with a peppery taste. At the tip of the beak is the persistent, sessile white stigma.
It is frost hardy, and even hard freezes only temporarily interrupt bloom. In Australia, it is regarded as a habitat threatening invasive species in many areas. In Canada, it is a naturalized species and sometimes hybridizes with cultivated radish, R. sativus. It has also proved to be resistant to several herbicides.
In the southeastern USA, the pale yellow form is common, sometimes entirely taking over fields in wintertime. It is a significant source of pollen and nectar for a variety of pollinators, especially honey bees during the very early spring starting buildup. Female Andrena agilissima, or mining bees, frequent this plant to obtain pollen and nectar. Other pollinators include cabbage butterflies and a few syrphid fly species.
II. How to Grow and Care
Wild radish is typically known for its resilience and adaptability, exhibiting an easy care difficulty level. Key care points include ensuring full sunlight and providing well-draining soil, as wild radish thrives in these conditions. It is important to manage its growth, as wild radish can exhibit weedy behavior if not controlled. Minimal watering is required since wild radish is drought-tolerant once established.
Sunlight
Wild radish should be provided with full sun, though some light shade will not cause any problems. Though it benefits from sunlight, wild radish will not do well in higher temperatures.
Temperature
Wild radish is frost hardy, with even a full hard frost only temporarily interrupting growth and bloom. Most varieties grow best in cooler weather; particularly spring varieties. Asiatic and summer varieties will tolerate warmer weather and are more likely to be stunted by colder soil conditions.
Watering
Thriving in its natural habitat, wild radish has adapted to regular hydration cycles, indicative of its origins that often experience consistent rainfall. This species is characterized by a moderate drought tolerance and appreciates a stable moisture environment. Accordingly, it should be watered every week to maintain optimal health. As an herbaceous plant, wild radish benefits significantly from watering during its active growing season, ensuring vigorous growth and resilience.
Soil
Wild radish grows a long, thick taproot, able to penetrate up to 2 m into the soil. Soil type or quality is therefore unimportant – the plant will reach down to the required depth to find moisture and nutrients. This also means that wild radish can be planted in thick, dense soils where other plants would be unable to grow. However, given a preference, wild radish will grow best in fertile, well-aerated soils, with both good drainage and adequate moisture.
Fertilizing
To bolster wild radish’s vigorous growth, utilize balanced nutrition fertilizers monthly during the growing season for optimal vitality, and switch to high nitrogen variants in early stages to encourage leafy expansion. Over-fertilizing can inhibit flowering, so apply sparingly, tracking growth response. Seasonal adjustments are key; reduce frequency in dormancy periods. Practical tip: dilute fertilizer to half strength to prevent root burn and ensure even soil distribution for efficacy.
Propagation
Native to Eurasia, wild radish is a weedy species known for its rapid growth and ability to thrive in disturbed soils. Effective propagation is commonly achieved through sowing its seeds directly into the soil, which have a high germination rate. For successful establishment, it prefers a well-draining substrate and can tolerate a range of soil types. It’s important to space the seeds adequately to prevent overcrowding, allowing each plant enough room to develop a healthy root system. Regular watering promotes vigorous growth, although wild radish displays a level of drought resistance once established.
Transplanting
For wild radish, the optimal transplanting time is during the vibrant growth of mid to late spring, ensuring a harmonious transition. Choose a sunny location with well-draining soil, and gently acclimate wild radish to its new environment for best results.
III. Uses and Benefits
All tender parts of the plant are edible. The leaves and flowers have a spicy taste or aftertaste. The seed pods can be eaten, as can the outer skin of the root (after being washed). It is said that John Walker cultivated sea radish root as an alternative to horseradish after discovering the plant on the west coast of Scotland as early as 1753.
IV. Harvesting and Storage
Wild radish grows very quickly and roots can be harvested and consumed about four weeks after sowing. For spring varieties of wild radish, the top portion of the bulbous root will be visible above the soil, indicating its readiness for picking. When the area of the root above the soil has a diameter of 2.5 cm, it is ready to pick. Wild radish can be harvested simply by pulling and, if necessary, loosening the soil surrounding the root by hand or with a garden fork.
