How do you use preemergent herbicide for crabgrass prevention?

Pre-emergent herbicides offer effective crabgrass control. Unless you take control, this warm-season annual spreads rapidly once growing conditions are correct. For best control, choose a product offering one of these active ingredients: benefin, trifluralin, dithiopyr, pendimethalin or prodiamine.

1. Time the application

   Apply the product so that it is still active when the seeds begin to germinate for best results. Look for indicators such as soil temperatures between 50 and 60 degrees Fahrenheit and the blooming of the forsythia. If you have missed the window for ideal application, a product offering pre-emergent and post-emergent protection is an option, providing up to six months of protection. Do not apply pre-emergent herbicides to newly seeded lawns, as they also prevent germination of the new grass seed.

2. Apply the product

   Follow the product label direction carefully. Application of more than the recommended amount of some pre-emergent herbicides causes damage to the root system of the existing lawn grass. Use a rotary spreader set to the recommended application rate for the product.

3. Water the pre-emergent herbicide into place

   Apply the herbicide before a light rainfall, or use the irrigation system to move the product, even if applied as a liquid, from the leaves of the grass into the soil, where it prevents germination. Apply approximately ½ inch of water to the lawn.