Mustard as a Cover Crop
Brassica cover crop
Mustard is a fast-growing brassica cover crop grown widely across the United States to give quick soil coverage between cash crops. Gardeners and small farmers value it for producing abundant leafy growth in a short window, which makes it a practical choice for filling short gaps in a rotation. Because conditions vary from region to region, your local Cooperative Extension office can help you match a mustard type to your area.
Benefits
As a brassica rather than a legume, mustard does not add nitrogen from the air, but its vigorous roots take up and hold leftover soil nutrients that might otherwise wash or leach away. The dense canopy shades the ground, which can help suppress many weeds and reduce erosion from wind and rain. When the leafy tops are returned to the soil, they add organic matter that supports soil structure and biological activity. Some growers also chop and incorporate mustard residue in an effort to reduce certain soilborne pests, though results vary widely and are best discussed with your local Extension office.
When to plant
Mustard is usually planted during the cooler parts of the growing season, such as early spring or late summer into fall, since it grows best in mild temperatures. Seed is typically broadcast or drilled into a firm, prepared seedbed and then lightly covered, with general seeding ranges available from seed suppliers or your Cooperative Extension. Aim to sow early enough that the plants can put on good growth before very hot or very cold weather sets in.
Growing it
Mustard germinates quickly and can reach usable size within a few weeks under favorable conditions, forming a leafy stand above a branching root system. It performs best with adequate moisture and a well-prepared seedbed, and it generally needs little attention once established. Because it belongs to the same plant family as cabbage and canola, plan your rotation so mustard does not immediately precede or follow closely related crops.
Ending the cover crop
The most common way to end a mustard stand without chemicals is to mow or cut the plants and then turn the residue into the soil while the tissue is still green and tender, which speeds breakdown. Where winters are cold enough, mustard will often winterkill on its own, leaving surface residue that can be worked in later. Terminating before the plants set seed helps prevent unwanted volunteer mustard in the following crop.
Best for
Mustard suits gardeners and small farmers who want fast ground cover for a short window between crops and who are mainly looking to scavenge leftover nutrients and add organic matter rather than fix nitrogen.
General guidance for US growers. Seeding rates and regional mixes vary; your local Cooperative Extension office and NRCS can help you plan. Page updated Aug 4, 2026.