Black Mustard: Green Manure and Essential Condiment

In the fields as on the plate, mustard is a plant that deserves much interest. Whether the seed is white, black, or brown, we are used to seeing the yellow flowers of mustard brighten up our landscapes in spring, sowing can be done from August to September to benefit from green manure in winter. On the other hand, this plant is sown in April-May if the goal is to use the seeds, harvested after the summer.

Black mustard ( Brassica nigra ) is distinguished from other varieties by the appearance of its seeds, which are smaller and brown to black in color, but also by the size of the plant, which can be around 2 m against barely more than 1m for white mustard.

If this plant is so popular, it is mainly for its qualities of intermediate culture and green manure.

In fact, undemanding and resistant to cold, mustard grows quickly, thus limiting the installation of weeds after a crop, and protects the soil from erosion and from the escape of nutrients, more particularly nitrogen, during periods of frost and winter rains.

In addition, its taproot, typical of the Brassicaceae family (cabbage, radish, etc.), helps to aerate the soil by working it naturally in-depth. On the other hand, it is crucial to set up a crop rotation, and to alternate vegetable species: after mustard, a plant of the Brassicaceae family cannot be established in the same place until at least 3 years later.

In this way, we drastically reduce the risk of the arrival of parasites, and in particular the flea beetle, a small beetle that punctures the leaves and causes significant damage. The alternation of crops also allows the soil to rebuild stocks of sulfur and potash, elements heavily consumed by Brassicaceae. On the other hand, by its allelopathic action, mustard certainly emits compounds which have a fungicidal impact on pathogenic fungi which may be underground, but it also influences other organisms, and can, if rotations are not applied, disturb the flora, the microflora, even the fauna of the soil, guaranteeing the balance of the system.

After having benefited from all its advantages, the destruction of the cover just before flowering and its incorporation on the surface effectively enriches the soil and promotes the growth of future crops…

But this is not the only interest of mustard!

Consumed worldwide, the condiment obtained from the seeds makes the dishes pleasant. And it is possible to make it yourself! The famous ocher color of the condiment may suggest that only white mustard, which produces yellow seeds, is used. This is indeed the case for certain preparations, but by way of example, Dijon mustard is made mainly from black mustard seeds, more pungent than the white variety, and less bitter than the seeds of brown mustard.

To transform your own mustard crop into a condiment, you must first let the plants make their seeds. It also means that the mustard will have had time to flower, and therefore to attract pollinators and foragers of all kinds, actors of biodiversity. Harvesting takes place at the end of summer, when the “pods” – the pods in which the seeds are produced – are well filled, just before they reach maturity and turn brown. The cut stems are allowed to dry, protected from light, in a dry and ventilated place. Once the stems are dry, the seeds can finally be extracted: depending on the quantity harvested, the pods are beaten over a sieve, or opened individually by hand (beware, spicy stems!).

Now is the time to prepare your own condiment, which only requires the basics of the closet.

Ingredients for about 150gr of mustard:

  • 30gr of mustard seeds
  • 30mL of apple cider vinegar
  • 50mL of water
  • 20mL of olive oil
  • 20gr of flour
  • 12gr of honey
  • salt
  • black pepper
  • 1 pinch of turmeric (optional)


  1. Soak the mustard seeds for at least 4 hours in vinegar and water.
  2. Add the other ingredients, and mix finely in the blender (by impulse, so as not to heat the preparation and denature the spicy flavor of the seeds).
  3. Adjust the seasoning according to your tastes (salt, pepper, honey, vinegar, etc.).
  4. Put in a jar and keep cool.

Note: This recipe leaves room for many variations. Spices (curry, cinnamon, cloves, ginger, etc.) and herbs (tarragon, Provence herbs, etc.) can be incorporated. Aromas of nuts, brought by vinegar or oil, will particularly bring out the flavors of the mustard seeds.

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