As a result, mustard produced in North America is used primarily as a spice or condiment. Growth Habit Mustard is an annual herb with seedlings that emerge rapidly, but then usually grow slowly. Plants cover the ground in 4 to 5 weeks with favorable moisture and temperature conditions. The tap roots will grow 5 ft into the soil under dry conditions, which allows for efficient use of stored soil moisture. Plant height at maturity varies from 30 to 45 in.
Flower buds are visible about five weeks after emergence.
The crop will appear to be rather uneven at this stage of development. Yellow flowers begin to appear 7 to 10 days later and continue blooming for a longer period with an adequate water supply. The stand will then appear more even. A longer flowering period increases the yield potential. About half of the flowers produce dark, reddish-brown seeds that are retained in pods of 0.5 to 0.75 in. in length.