Yellow Mustard


There are several varieties of mustard that get used in Cover Cropping situations. We don’t try to carry them all. Yellow mustard is a quick growing annual, cool season, broadleaf, upright plant. It has low water requirements and develops a thick taproot as well as a dense root structure helping create a good deal of organic matter under the soil.  Be careful to plant late enough to allow mustard to winter kill, or till or herbicide kill it before it goes to seed. It can produce a large quantity of seed and it has high dormancy so you can have mustard reproducing for many years if you let it go to seed. Mustard can tolerate higher salinity but not shade so plant your mustard at the same time as other crops. If you interseed it into existing plants it will not thrive. It does flower and attract many beneficial insects making it a good crop to add to an annual pollinator mix.

One of mustard’s big claims to fame is its biofumigant (glucosinolates) property. When the plant is decomposing it releases these biofumigants which are toxic to some soil pathogens and pests including some small seeded weeds. Don’t think this is a miracle plant, it can’t eradicate everything and the interactions are not fully understood but who would not want a natural boost to their weed control efforts? It does mean that you should not plant directly into decomposing mustard – wait about three weeks.

C:N Ratio: 20-30:1


Additional Information

  • Variety Release Sheet:
  • USDA Sheet:


Southwest Seed is happy to help. Please feel free to call or email us for more information about our products and services. Before you get in touch, you might take a look at our Planning Guide. It has information that you can gather prior to contacting us so that we can efficiently answer your questions.