How to Grow and Care for Black Mustard

Black mustard herb plant with bright yellow flowers on thin stems against blue sky

The Spruce / Evgeniya Vlasova

In This Article

Black mustard (Brassica nigra)  is one of the oldest and most useful spices and herbs known. Its young leaves are used as salad greens, its mature leaves are eaten boiled or sauteed, and its seeds are the source for the tart condiment that bears its name. This beautiful herb native to North Africa and Eurasia is so loved that it has spread worldwide. Both commercial and residential growers have planted it widely, leading to its introduction into local ecosystems.

Black mustard is very easy to grow and will thrive in almost any soil condition. It also reseeds readily which results in rapid spread and this has allowed the plant to naturalize almost everywhere it has been introduced. A consequence of rapid spread has led some areas to label black mustard as invasive. Adding to the problem is the allelopathic tendencies of the mustard plant which inhibits the growth of native flora.

Black mustard is beautiful, delicious, nutritious, and actually very good for the soil it is planted in when its controlled. If you decide to include black mustard in your garden, be prepared take necessary steps to prevent the plant's spread into the local ecosystem.

Botanical Name Brassica nigra
Common Name Black mustard
Plant Type  Herb, Annual
Mature Size 2 to 8 ft. tall
Sun Exposure Full sun
Soil Type Rich, Moist Loams,
Soil pH Neutral
Bloom Time March to June
Flower Color Bright Yellow
Hardiness Zones USDA zones 4-7
Native Area  North Africa, Eurasia

Black Mustard Care

Black mustard is easy to grow. There is not much that can go wrong when growing it unless you give it too much water or if the plant gets too hot.

When you plant your black mustard, there are so many great uses for the seeds. Be sure to collect them all, and you can avoid spreading this non-native. After all, native plants are better for the environment and our gardens.

Black mustard herb plant with bright yellow flowers on tall thin stems covering field

The Spruce / Evgeniya Vlasova

Black mustard plant stem with small bright yellow flowers on end closeup

The Spruce / Evgeniya Vlasova

Black mustard herb plants with small yellow flowers clustered together in field

The Spruce / Evgeniya Vlasova

Light

Black mustard grows naturally in meadows and at the edges of tilled land. It needs full sun to grow and perform its best and does not tolerate shade well.

Soil

Though it will grow almost anywhere, mustard prefers moist and loamy that is loose, and well-draining. The pH range of the soil should fall somewhere between 6 and 7. An easy test of your soil can be taken to determine the pH, and you can watch how your plants are doing.

Water

There is no magic number on how much water to give. Consider your weather and keep it consistently moist without letting the plant sit in standing water, and it will thrive. If your soil is well-draining over watering shouldn't become a problem.

Temperature and Humidity

Black mustard, like many leafy greens, is a cool season crop which grows best before air temperatures heat up and humidity increases. When temperatures are too warm, the plant goes to seed much more quickly with seeds that can ripen much faster and burst. This could lead to fields of black mustard in your yard and possibly your neighbor's as well. Black mustard does great in USDA Zones 4-7.

Fertilizer

Depending on the richness of your soil, the addition of fertilzer may not be needed but tilling manure into the soil before planting is going to give your mustard extra peppy flavor and give it a boost. Growing nitrogen fixers like beans and turnips next to your mustard is a good practice since mustard uses a lot of the available nitrogen in soil.

Propagating Black Mustard

Black mustard is easily grown from seed sown directly into the soil. The seeds are very small so it often works best to scatter sow within a row, cover with a light layer of soil and then thin the plants once seedlings have emerged.

Harvesting Black Mustard

Mustard can be harvested as a cut-and-come-again crop. Keep in mind that once the weather heats up, you will need to watch for your plants to bolt and go into seed production. Harvest the seed pods which can be added as a whole spice in food preparation. You can also make your own mustard by grinding the seeds to powder and mixing it with vinegar and other ingredients.