Plan the perfect garden with our interactive tool →

How to Germinate Mustard Seeds

SyedMirazurRahman/iStock/Getty Images

Mustard (Brassica spp.) is a cool-season crop in the cabbage family (Cruciferae spp.). While the tender young leaves are harvested as a vegetable and salad green, the seeds are used as spice. Mustard seed is used in various world cuisines to lend pungent flavor to curries, culinary oils and condiments, including prepared mustard. Growing mustard at home from seed is simple; the first step is successful germination.

Germinating in Containers

If you start mustard seeds in containers, use quality potting mix as the growing medium. Scatter a handful of seeds over the surface and cover lightly with additional potting mix and just enough water to evenly moisten soil. Place containers in a warm place indoors or in a greenhouse and keep evenly moist until germination occurs in four to seven days.

Sowing Outdoors

You can sow mustard seeds directly into the garden four to six weeks before your last frost date in spring. Soil should be organically rich and well-drained** with a pH of 5.5 to 6.8 and have a temperature of 40 degrees Fahrenheit or more, or germination will be slow. If the soil needs enhancement, work 1 to 2 pounds of granular 5-10-10 fertilizer into the top 3 inches of soil for every 100 square feet of row. Sow seed 1/8 to 1/2 inch deep and 15 inches apart. In U.S. Department of Agriculture plant hardiness zone 8 and above, mustard can be seeded in September or October as a winter crop. In USDA zone 4 and below, seed in July.

  • If you start mustard seeds in containers, use quality potting mix as the growing medium.
  • Scatter a handful of seeds over the surface and cover lightly with additional potting mix and just enough water to evenly moisten soil.
  • Place containers in a warm place indoors or in a greenhouse and keep evenly moist until germination occurs in four to seven days.
  • You can sow mustard seeds directly into the garden four to six weeks before your last frost date in spring.

Common Problems

One of the most common causes of germination failure is overwatering, which results in rotting seeds. Seeds need sufficient warmth to germinate but not extreme heat or direct sunlight, which can prevent germination or kill seedlings off almost as soon as they appear. Other factors that hinder germination include planting seeds too deeply or in heavy, clay soil.

Mustard Varieties

There are different varieties of mustard seed. The mildest in flavor is white mustard (Brassica alba), which is typically used in relishes and pickling seasoning. Brown mustard seed (Brassica juncea) is the most pungent and is used in Dijon style and Chinese hot mustards and is the kind germinated for greens. The moderately spicy black mustard seed (Brassica nigra) is used in Indian cuisine.

  • One of the most common causes of germination failure is overwatering, which results in rotting seeds.
  • Brown mustard seed (Brassica juncea) is the most pungent and is used in Dijon style and Chinese hot mustards and is the kind germinated for greens.

Seed Sources

You can purchase mustard seeds from a local nursery or an online vendor, but the Mother Nature Network notes that these are no different that the whole seeds found in the spice isle at the grocery store. There’s no guarantee, though, that store-bought seeds will germinate because the expiration date on the jar doesn’t tell you how long the seeds sat in a warehouse or on the shelf at the store. Test a few to see if they sprout. If they don’t, make mustard.

Related Articles

How to Prepare Jalapeno Seeds for Planting
How to Prepare Jalapeno Seeds for Planting
Celery Flakes Vs. Celery Seeds
Celery Flakes Vs. Celery Seeds
How to Clean Bean Sprout Seeds With Bleach Solution
How to Clean Bean Sprout Seeds With Bleach Solution
How to Harvest Wheatgrass Seeds
How to Harvest Wheatgrass Seeds
How to Grow Cilantro in Phoenix
How to Grow Cilantro in Phoenix
How Long Is the Oat Growing Season?
How Long Is the Oat Growing Season?
How to Plant Seeds in Cups
How to Plant Seeds in Cups
Vegetable Garden Plants in Fresno
Vegetable Garden Plants in Fresno
The Best Herbs to Grow in Zone 10
The Best Herbs to Grow in Zone 10
How Long Does It Take for Soybeans to Emerge From the Soil?
How Long Does It Take for Soybeans to Emerge From the...
Vegetables That Grow Well in Arizona Gardens
Vegetables That Grow Well in Arizona Gardens
Black Vs. White Sesame Seeds
Black Vs. White Sesame Seeds
Vegetable Planting Rates Per Acre
Vegetable Planting Rates Per Acre
Gray Vs. Black Sunflower Seeds for Sprouting
Gray Vs. Black Sunflower Seeds for Sprouting
Garden Guides
×