White mustard, the seeds give the plant its name

White mustard actually has yellow flowers

White mustard is turning increasingly popular: many are discovering its use as a green garden fertilizer, with the side benefits of being a delicious edible spice!

White mustard, a few key facts:

Botanical nameSinapis alba
Common name – white mustard
Family – Brassicaceae

Type – spice
Height – 2 ½ feet (70 cm) to 4 feet (120 cm)
Planting distance – 2 grams of seeds (a pinch) per sq. yard (m²)

Exposure – sun
Soil type – cool, rich and light

Planting – March to May, August to September
Harvest – May to August

White mustard is a herbaceous annual plant that produces fuzzy, branching stems, serrated (toothy) and lobed leaves, and clusters of small yellow flowers. Typically, it’s used as green manure to increase soil quality. White mustard both enriches the soil it grows in and absorbs noxious nitrates. It also repels nematodes.

Interestingly, this plant is also a perfectly edible spice. The most refined mustards on the Old Continent use its large pale yellow seeds as a key ingredient. Native to North Africa, Europe and the Middle East, white mustard is very easy to grow and doesn’t require much care. A word of caution: don’t confuse white mustard with China mustard.

Sowing white mustard

You should always sow white mustard directly in the plot. Do so anytime from March to May if you hope to harvest its seeds, or from August to September if your goal is to use it as green manure for your vegetable plot.

  • First of all, rake the area clean and make the ground level. Then, douse it with water to make the soil moist and cool. Finally, sow the mustard seeds:
  • Simply use the age-old technique of broadcast sowing – basically throwing the seeds every here and there, but only sprinkle about 2 grams of seeds per square yard or meter.
  • Keep a watchful eye on the seeds until they sprout: soil must remain cool and humid, but not drenched continuously.

Care and cultivation

Not a very demanding plant at all, actually clearly on the “tolerant of almost any situation” side of things. It’ll even sprout on its own almost anywhere if you drop a few seeds along the way. White mustard is a hardy plant with an annual vegetative cycle that can make do with any soil type.

To truly thrive, however, rich, light and cool soil is the key. It doesn’t like excess moisture, drought, or shade very much. A good location for this spice is full sun or part shade. As long as it gets regular rain and enough sun, white mustard needs absolutely no humanLeaf of white mustard held up with a hand intervention at all to keep reappearing year after year. If ever rains are tardy, though, grab the watering can for a round of watering to keep the soil cool.

Diseases and pests

White mustard is a plant that is highly resistant to most diseases, apart perhaps from clubroot (a form of root rot).

Pests, however, are another matter. Slugs love eating young tender shoots, and older plants are a compatible cabbage moth host.

Companion planting with Sinapis alba white mustard

This plant hasn’t been breed and selected much for disease resistance, so most of its defenses are still inherited from its natural state. The only precaution is to avoid planting mustard and cabbage too close together, or even after one another if you practice crop rotation. Since they’re all from the same family, pests and fungus might spread from one to the other.

Harvest and keeping

A bowl of white mustard seedsFor use as a spice, collect the mustard seed pods when they’re already quite dry, which is usually 2 months after having been sown in Spring.

  • To time it perfectly, just remember that you have to snip the stems before the pods turn brown.
  • Wrap the stems into a bundle, then hang them upside-down in a dry shaded place until completely dry. At this point, ruffle them up above a large salad bowl to catch the seeds as they fall.
  • You can keep these seeds for a long time away from sunlight in a dry room of the house.

Directions for use as a green manure/green fertilizer

White mustard can fertilize your growing beds: before the plants go to seed, cut them at the base with a sickle or hedge trimmers. Another alternative is to mow them over with a mower in the “mulching” position. The goal is to shred everything up and let the residual clippings sit on the ground as a layer of mulch.

  • Apart from mulch, you can also collect white mustard leaves to make a fresh batch of fermented weed tea. It will make for a great fast-acting fertilizer.

Cooking with white mustard

Young stems are also edible – they’re quite tasty, too! Pick them when they’re still soft. White mustard leaves and shoots are simply delicious when added to mesclun, as a greens in sandwiches, or to replace arugula on pizza. Seeds are almost exclusively destined to become mustard. Steps to make it involve crushing them and mixing the paste with water and vinegar. Connoisseurs know that the seeds can also be eaten raw or grilled. Just add them to your meals, and marinades for the barbecue…

Smart tip about white mustard

Plant only a few square feet for a bowl full of seeds.


Credits for images shared to Nature & Garden (all edits by Gaspard Lorthiois):
Yellow white mustard flower by Valentin Kold Gundersen under © CC BY 2.0
White mustard leaves by Karim Haddad under © CC BY 4.0
Seeds gathered and ready to eat! by Enotovyj under Pixabay license