Growth Time of a Mustard Plant

Timing

• Fall-planted mustard tastes better, according to master gardeners with Utah State University's Cooperative Extension. Other suitable times to plant include spring, three weeks before the last frost and again three weeks after that. Plant when the soil temperature exceeds 40 degrees Fahrenheit. The ideal germination temperature is between 55 and 65 degrees. Under ideal conditions, the seeds germinate within 10 days and harvest occurs 45 to 50 days later.

Seedbed Preparation

• Mustard thrives in well-drained, fertile soil. Amend the soil if it is heavy and drains slowly. Add 2 to 3 inches of builder's sand or compost and blend it into the top 6 inches of native soil. Add 4 cups of 16-16-8 fertilizer per 100 feet of seedbed as well, and work that into the soil with the other amendments. For spring planting, work the soil in the prior fall so that the amendments have time to disperse over the winter.

Planting

• Plant the mustard seed 1/3-inch deep, 3 inches apart. For multiple-row plantings, space the rows 1 foot apart. Water the seedbed with a fine mist to avoid washing away the tiny seeds, keeping the bed moist during germination. An application of mulch over the top of the bed helps keep the seeds in place and the soil to retain moisture and remain cool. Use a light, organic mulch, such as straw or grass clippings.

Care

• Remove weak seedlings to thin the mustard plants to 5 inches apart when they reach 3 inches in height. Four weeks later, fertilize the mustard plants with 1/2 cup of 21-0-0 fertilizer per 10 foot row. Side dressing the plants helps avoid burning the roots. To side dress, dig a 2-inch-deep trench, 4 inches alongside the row, sprinkle the fertilizer along the bottom of the trench and fill it in with soil. Water to a depth of 10 inches after fertilizing to help soak it into the root zone. Keep the soil consistently moist during growth. According to the specialists with the University of Illinois, fluctuations in moisture content may cause the mustard plant to produce tough, inedible leaves.