Corn Gluten

• Corn gluten will prevent dandelion seeds from germinating.Photos.com/Photos.com/Getty Images
  
  Corn gluten is a by-product of the corn milling process. The meal from corn gluten is used in both pre-emergent weed killers and animal feed. This product is considered organic and safe to use around your children and pets. Iowa State University first discovered the germination inhibiting properties of corn gluten when it was being used in a turfgrass disease study. They noticed that it prevented grass seed from germinating as well as other weedy species.
  
  

How to use Corn Gluten in Your Vegetable Garden

• Corn gluten also contains 10% nitrogen to feed your plants as well as prevent weeds.Jupiterimages/Photos.com/Getty Images
  
  Corn gluten will prevent any seeds from germinating, including your vegetable seeds. Corn gluten comes in a granular form that can be broadcast around your vegetables after they have true leaves and are 2 to 3 inches tall. Corn gluten is safe around all vegetables, and will last four to six weeks. Additional applications should be made monthly. Application rates will vary depending upon the company manufacturing it, so check your labels before applying.
  
  

Trifluralin

• Treflan can be used on carrots prior to seeding.Hemera Technologies/AbleStock.com/Getty Images
  
  The trade name for trifluralin is Treflan and is readily available in many different forms manufactured by many different companies. Treflan can be found in sprays, wettable powder and granules. Treflan is a synthetic chemical pre-emergent that has some vegetables registered and listed as being safe to use around. Trelfan is unique in the fact that it can be used on some vegetables before they are seeded, unlike corn gluten that must be used after plants are established.
  
  

How to Use Treflan

• Make sure to use Treflan before spear emerge on established asparagus plants.Photos.com/PhotoObjects.net/Getty Images
  
  Treflan can be used before seeding on these vegetables: broccoli, Brussels sprouts, cabbage, carrots, cauliflower, celery, collard, black-eyed peas, field peas, green peas, kale, lentils, Lima beans, mustard greens, okra, radish, Southern peas (cow peas), snap beans and turnip greens. Use treflan after seeding cantaloupes, cucumbers and watermelon when they have five or more leaves. You can also use Treflan after planting potatoes and before transplanting starts of celery, broccoli, Brussels sprouts, cabbage, cauliflower, eggplant, peppers, onions and tomatoes. Use around asparagus before spears emerge in the spring. Trelfan will last for nine to 12 weeks in your garden and should be re-applied every eight weeks.