How to Grow and Care for the Mustard Plant

The name mustard plant commonly refers to three species of a hardy annual vegetable: brown mustard (Brassica juncea), white (also known as yellow) mustard (Brassica alba), and black mustard (Brassica nigra). The first two are used to make mustard and yellow (white) mustard is the most common.

The mustard plant is grown for its leaves, also sold as mustard greens, or for its seeds to make mustard. It grows about 3 feet tall with bright yellow flowers, which are also edible.

Mustard is not finicky and easy to grow, but because it’s a cool-weather crop, proper timing of the planting is important.

Common name	Mustard plant
Botanical Name	Brassica spp.
Family	Brassicaceae
Plant Type	Annual, vegetable
Size	Up to 3 feet
Sun Exposure	Full
Soil Type	Well-drained
Soil pH	Acidic
Bloom Time	Summer, fall
Flower Color	Yellow
Hardiness Zones	2-11 (USDA), depending on the species
Native Area	Europe, Asia, Africa, Middle East, Mediterranean

How to Plant Mustard

When to Plant

Plant mustard in the spring or fall. In the spring, plant it as soon as the soil temperature remains above 40°F.1 Because mustard prefers cool weather, a fall harvest usually produces better quality.

For fall plantings, select varieties that mature early. Plant the mustard in the late summer or, if you live more south, in September or October for a fall and winter harvest. To calculate your fall planting date, add 2 to 3 weeks to your average first frost date. Then count back 50 to 75 days (or the anticipated maturity date of the variety you are growing).

Where to Plant

Plant mustard in a location with full sun and well-draining soil. The soil should also be loamy, and nutrient-rich. Make sure to follow the rules of crop rotation and don’t plant it in the same spot where other members of the Brassica family were grown in the past two years or ideally even longer. 

How to Plant

Space rows of mustard greens that are harvested regularly at least 12 inches apart and plant mustard with fully developed seed heads in rows 2 to 3 feet apart. The space between the plants and the rows depends on the variety, and also on what you grow the plants for.

Closely spacing the plants (and thinning them as they grow) helps to control weeds. When growing mustard for seed, staking the plants is recommended. 

Mustard Plant Care 

Mustard is easy to grow when cared for correctly:

• Grow mustard in full sun.
• Plant it in well-draining, moist, fertile, and slightly acidic soil.
• Give mustard consistent moisture.
• Feed it with a fertilizer high in nitrogen.

 

 

 

Light

Grow mustard in full sun. Partial shade is only acceptable for baby greens, which need to be protected from the strong sun as the weather turns hot.

Soil

While mustard grows in most soils, a fertile, moist, well-draining, slightly acidic soil with a pH below 6.0 is best.

Water

As a cool-season crop, mustard needs consistent moisture without being overwatered. Give it at least 1 inch of water in the absence of rain. In dry soil conditions, leaf growth is slow, the leaves will be tough and have an off-flavor.

Temperature and Humidity

Cool weather, even down to 32°F, is not a problem for mustard. On the other end. the plant does not do well in temperatures over 75°F.

Fertilizer

Choose a fertilizer that is high in nitrogen, following label instructions for the amount. Scatter it around the seedings when they have reached 3 to 4 inches in height. 

Pollination

Although mustard is self-pollinating, pollination is nonetheless a consideration because pollinating insects can cross-pollinate the flowers of different varieties within a 2-mile radius. That means that if you want to save the seeds for next year’s planting, do not plant different varieties at the same time (and hopefully nobody in your neighborhood grows mustard either).

Types of Mustard Plants

The three main types of mustard plants are

• White or yellow mustard (Brassica alba, other botanical name: Sinapsis alba). Zone 4-7. This is the mildest tasting of all mustards. Its seeds are used to make prepared mustard. It is not grown for its greens.
• Brown mustard (Brassica juncea). Zone 2-11. This is the hottest mustard. The seeds are used for Dijon-type mustards, Chinese hot mustards, and curries. It is also grown for its greens and there are several cultivars. Popular ones include ‘Giant Red’, ‘Red Garnet’, and ‘Southern Giant’ with curled leaves.
• Black mustard (Brassica nigra). Zone 6-9. The seeds are used for moderately spicy mustard and are also included in Dijon-style mustard. The seeds are also used in Southeast Asian cooking. It is not grown for its greens.

Harvesting Mustard Greens and Seed

The methods you use will change depending on whether you are harvesting the leaves or the seeds of the mustard plant.

Harvesting Mustard Greens

For salads, harvest the mustard greens when they are small, young, and tender. For sautéing or stewing, let the leaves grow to their full mature size but harvest them before a seed stalk forms.

1. Cut the large outside leaves at the base without damaging the growing point. Even if you don’t use the large leaves, remove them anyway to make room for the small, more tender inner leaves that will continue to grow. The leaves will regrow even after cutting them repeatedly.
2. Harvesting mustard after the first frost is not a problem, in fact, the flavor of the greens even becomes sweeter with a light frost.

Harvesting Mustard Seeds

Watch the plants closely after the bloom to catch the point in time when the seed pods turn from green to brown but aren’t open yet because otherwise, they will disperse the seeds all over your garden.

1. Either cut off the branches with the mature seed pods or remove the entire plants.
2. Place an old sheet on the ground, which makes it easier to gather any seeds and seed pods that fall off the plants.
3. Air-dry the pods on a tray lined with an old sheet or on a fine screen for about 2 weeks.
4. Alternatively, place them in paper bags and hang them in a warm, dry place. The seed pods are ready for further processing or storage when they are completely dry and crispy.

Making Mustard Out of Seeds

After the mustard seeds have dried inside the husks, which have turned brown at this stage, the seeds must be threshed to remove the seeds and hulls. If you only have a small amount, rub the husks between the palms of your hands over a large bowl.

After separating the seeds from the chaff, the seeds can be ground or used whole to make mustard. (More than just mustard seeds are required to make mustard, though they are a key ingredient.)

How to Grow Mustard Plants in Pots

Mustard can be planted in pots, but that option is only suitable when growing the plant for the greens, as you need a substantial number of plants to produce seeds for mustard.

Plant the seeds in pots of at least 8 inches in diameter and filled with well-draining potting mix. Thin seedlings to 4 inches apart.

Like all potted plants, mustard needs more frequent watering and fertilization than plants grown in the garden.

How to Grow the Mustard Plant from Seed

Although you can start mustard seedlings indoors, direct seeding is the preferred and easiest method to start mustard plants.

• Place the seeds 1 inch apart and ¼ to ½ inch deep in a prepared garden bed.
• Keep the soil evenly moist at all times. At temperatures between 45 and 75°F, the seeds germinate in 4 to 14 days.
• When seedlings are 3 to 4 inches tall, start thinning them out (they are edible) to 4 to 6 inches apart, and increase the space as the plants grow. Aim for 12 to 18 inches of space between large varieties and 6 to 10 inches between smaller, leaf-type varieties.

Common Pests and Plant Diseases

Mustard is not affected by serious pest and disease problems. In humid weather, it is 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 is another way to avoid pests. For example, plant mustard in the fall when populations of flea beetles are much lower.