Function

• Preen is a pre-emergent targeting grassy weeds. According to the manufacturer's label, the active ingredient in Preen is Trifluralin. Trifluralin inhibits the growth of grasses by inhibiting root formation. According to Viewpoints, a product review site, Preen rates 3.75 out of 5.00 for effectiveness.
  
  

Instructions

• To use Preen with vegetables, remove all existing weeds. According to the manufacturer's label, lightly rake the soil surface, and then mix the Preen into the top 1 to 2 inches of soil. Immediately water the product into the soil.
  
  

Considerations

• For some types of vegetables, seeds must be planted before applying Preen. For others, the label says to wait until after the application to plant. It is necessary to consult the label to know exactly when to plant seeds or plants when using Preen.
  
  

Warning

• This product carries a "Caution" label. It is banned in some countries outside the U.S.. Preen is extremely toxic to aquatic creatures. Care must be taken to avoid contaminating nearby water with runoff.