Black Mustard (Brassica nigra)

Black mustard (*Brassica nigra*) is a plant that grows annually from seed, native to North Africa, Europe, and Asia. It can grow in both tropical and temperate climates. This plant is known for its long seed pods, each containing four black seeds. The seeds from black mustard are used as a spice to make mustard. On the West Coast of the US, it is considered to be a noxious weed.

I. Appearance and Characteristics 

Rhamphospermum nigrum (syns. Brassica nigra and Sinapis nigra), black mustard, is an annual plant cultivated for its dark-brown-to-black seeds, which are commonly used as a spice. It is native to cooler regions of North Africa, temperate regions of Europe, and parts of Asia.

It was formally described by Karl Koch in “Deutschl. Fl.” (or Deutschlands Flora) ed.3 on page 713 in 1833. This was based on a description by the Swedish botanist Carl Linnaeus.

The Latin-specific epithet nigrum is derived from the Latin word for black. This is due to the black seeds.

It is an upright plant, with large stalked leaves. They are covered with hairs or bristles at the base, but on the stem smoother. It can reach up to 1.2 m (3 ft 11 in) tall in moist fertile soil. It blooms in summer, from May (in the UK) onwards. The flowers have four yellow petals, which are twice as long as the sepals. Each stem has around four flowers at the top, forming a ring around the stem. Later, the plant forms long seed pods, that contain rounded seeds.

II. How to Grow and Care

Sunlight

Like most plants, black mustard must be spaced adequately to ensure each plant receives enough sunlight on all above ground plant plants and to ensure that disease is unable to take hold. The majority of Brassicaceae will thrive in around 6 hours of direct sunlight each day. The plants should be positioned in full sun though care should be taken to ensure that they are protected from wind.

Temperature

Black mustard prefers to germinate and grow at relatively low temperatures. The biology of black mustard likes temperatures between approximately 20 to 25 ℃, but will also sprout at temperatures as low as 10 ℃. If temperatures are very low, planted seeds can be started on a heat mat and removed as soon as they have germinated. Brassica is one genus of vegetable with several well-known families which actually taste better after a frost; temperatures can drop below zero during the season.

Temperature is very important for the transition of black mustard from the vegetative to the reproductive phase. Whether growing these plants for leafy vegetables as a source of seeds or for breeding, temperature and timing should be carefully considered to achieve the desired result.

Plants of genus Brassica is sensitive to moisture regardless of family. The large leaves of black mustard require considerable amounts of water, however equally the roots require ample drainage. Sandy soils tend to lose moisture too quickly for this genus, whilst clay holds too much. Growing of black mustard therefore calls for use of organic matter to ensure an adequate balance of moisture. The organic matter will also hold and supply trace elements, buffer pH and support beneficial organisms.

Watering

Originating from the temperate regions, black mustard is accustomed to moderate moisture levels and can tolerate brief periods of dryness. This species thrives with a balance of hydration, indicative of its resilience in varying water conditions. Watering every week suffices to maintain its vigor. Given that black mustard is typically grown outdoors, it’s important to consider how natural rainfall contributes to its watering schedule, particularly during the growing season when its water requirements may increase.

Soil

Black mustard grows best in firm, fertile and naturally-draining soils. Areas to be planted should be dug over in the preceding fall, with stones removed and well-decomposed manure or compost worked in ready for the growing season. Growers can also tread on the soil area to ensure that air pockets have been removed and the surface made adequately firm. In terms of pH, all families of Brassica grow best in soils just below neutral at 6-7 except for collards and mustards which enjoy slightly more acidic soils and cabbages that will tolerate slightly alkaline soils up to a pH of 7.5.

Fertilizing

For black mustard, balanced nutrition fertilizer or one higher in nitrogen is beneficial. Apply moderately every 4-6 weeks during active growing season; a lighter dose is preferable. Fertilization boosts growth, yield, and vigor. Avoid over-fertilization, which can harm black mustard; use based on soil testing results. In cooler seasons, reduce frequency to match reduced growth rates. Always water black mustard after fertilizing to aid nutrient absorption and prevent root burn.

Pruning

The large, thick low-lying leaves characteristic of many brassicas call for fairly regular maintenance and occasional pruning to ensure that leaves touching the ground do not start to rot. As well as removing possible sites for diseases to take hold, it helps to ensure that the plant’s energy is directed towards healthier growth. Any yellow, flat-looking leaves can simply be torn off or pruned with scissors. Large, healthy leaves covering other plants can also be removed but should be eaten.

Propagation

Propagation of black mustard seedlings is best started indoors with seeds planted six to four weeks before the last frost in spring or, for a winter crop ten to twelve weeks before the first frost in the fall. The seeds should be sown to a depth of a 1.3 cm. Once germinated, seedlings can be thinned to 8 cm between each plant. They can be transplanted once a height of 6 cm has been reached; for Brussels sprouts and kale, the height should be about double this. Spacing then depends on Brassicaceae but ranges from 30 to 76 cm.

Transplanting

The prime season for transplanting black mustard is autumn; it ensures’sufficient time for root establishment before spring’s growth spurt. Choose a sunny site as black mustard thrives in full sun. In the beginning stage, regulate water and temperature to prevent shock, and ensure rich, well-draining soil for optimal growth.

Pests and Diseases

Mustard is not affected by serious pest and disease problems. In humid weather, it can be susceptible to powdery mildew and white mold. Common insect problems include aphids, whiteflies, cabbage worms, cabbage loopers, slugs, and flea beetles. If these are a problem in your area, protect the plants with row covers. Adjusting the planting time can also help. For example, to avoid flea beetles, plant mustard in the fall when populations are much lower.

III. Uses and Benefits 

• Ornamental uses

Black mustard’s weedy appearance doesn’t affect the plant’s popularity with gardeners. It is often found growing in herb and spice gardens, where the plant is prized for its dark-colored seeds and edible stems and leaves. When planted in groupings, the bright-colored summer flowers create a striking display in gardens.

• Folk medicinal uses

In the UK, the plant was used to make “hot mustard baths”, which would aid people with colds. Ground seeds of the plant mixed with honey are widely used in eastern Europe as a cough suppressant. In Eastern Canada, the use of mouche de moutarde to treat respiratory infections was popular before the advent of modern medicine. It consisted in mixing ground mustard seeds with flour and water, and creating a cataplasm with the paste. This poultice was put on the chest or the back and left until the person felt a stinging sensation. Mustard poultice could also be used to aid muscular pains.

• Culinary uses

More than 2,000 years ago, the plant was used as a condiment; it was mentioned by the Roman author Columella in the 1st century A.D. The plant leaves were also pickled in vinegar. In 13th century France the seeds were ground and used. They were mixed with unfermented grape juice (must) to create “moût-ardent” (“burning must”). This became later “moutarde”, or mustard in English.

A spice is generally made from ground seeds of the plant, with the seed coats removed. The small (1 mm) seeds are hard and vary in color from dark brown to black. They are flavorful, although they have almost no aroma. The seeds are commonly used in Indian cuisine, for example in curry, where it is known as rai. The seeds are usually thrown into hot oil or ghee, after which they pop, releasing a characteristic nutty flavor. The seeds have a significant amount of fatty oil, mainly oleic acid. This oil is used often as cooking oil in India, where it is called “sarson ka tel”.

The young leaves, buds and flowers are edible. In Ethiopia, where the plant is cultivated as a vegetable in Gondar, Harar and Shewa, the shoots and leaves are consumed cooked and the seeds used as a spice. Its Amharic name is senafitch.

Black mustard is thought to be the seed mentioned by Jesus in the Parable of the Mustard Seed.

Since the 1950s, black mustard has become less popular as compared to brown mustard, because some cultivars of brown mustard have seeds that can be mechanically harvested in a more efficient manner.

IV. Harvesting and Storage

Harvesting of brassicas depends on family and variety. Summer cabbages cauliflower kohl and common broccoli can all be harvested from the end of summer whilst many others are good for picking in the fall or winter. Low growing brassicas such as cabbages should be harvested by cutting close to the ground level using a sharp knife. When harvesting cabbages the whole plant should be lifted to reduce the risk of club root. Broccoli should be harvested when flower shoots are well formed. Kale on the other hand can be harvested throughout the season on a frequent basis.