Black mustard seeds (Brassica nigra)

Brassica nigra

Black mustard, black charlock, true mustard: Dijon mustard was traditionally made from its brown-black seeds, before brown mustard replaced it for mechanized harvesting reasons — its pods split too easily when ripe. In the garden, this former “weed” has become a top choice for green manure.

Characteristics:

• Tall annual: it grows over 1 meter tall, with broad leaves measuring 15 to 40 cm and bright yellow flowers.
• Fast-growing: ready to be mowed after just a few weeks.
• Improves soil health: its roots release sulfur compounds that help limit certain soil pests and smother weeds.

Sowing advice:

• Exposure: sunny.
• Soil: all types, including poor, clay or chalky soils — it adapts remarkably well, with a preference for moist soils. No fertilization needed: it will enrich the soil as it decomposes.
• Method: broadcast-sow directly in place after the last frosts, on raked soil. No pots or pre-soaking needed: germination is very fast, often in less than a week. See how to sow your seeds.

Care advice:

• None. Mow before it sets seed if you do not want it to reseed, then leave it as mulch or lightly dig it into the soil.

Beneficial combinations:

• Rotate it with green manures from other families, such as phacelia or white clover. Like white mustard, it is a brassica: avoid growing it before or after cabbages, as they share diseases and pests. Our guide: sowing green manures.

Benefits for biodiversity:

• Its yellow flowers, if allowed to bloom before being dug in, are highly visited by bees and hoverflies.
• Its dense cover protects bare soil from erosion and provides shelter for soil fauna — see the basics of living soil.

Uses:

• Its seeds, which are hotter than those of white mustard, are used as a condiment. The young leaves can be eaten in salads or cooked, with their characteristic spicy flavor.

Harvesting your own seeds:
Be careful: its siliques split open as soon as they ripen and project the seeds. Monitor them and harvest the stems as soon as they turn brown, before they open, then let them dry in a paper bag that will collect the seeds. See storing your seeds.

Commitment to Quality: at SemiSauvage - Permaculture, we grow and select our seeds with respect for all living things as our guiding principle. Based near the Auvergne volcanoes, we choose reproducible, non-hybrid varieties, tested for their germination rate, carefully sorted and packaged, with no chemical treatment. Our conviction: to give gardeners back the ability to resow, year after year, seeds that truly belong to them.

Add these black mustard seeds to your garden for healthy, fertile soil.