What Is The Best Timing For Weed Control?

The optimum time to control weeds depends on the type and life cycle of the weed and, in some cases, the specific weed and specific herbicide, so the optimum time to control weeds is a complex answer. Regardless of the timing and weed, it is important to select herbicides with a high efficacy for the specific weeds you are targeting.

Spring applications of post-emergents can be used to target perennial broadleaf weeds, especially if an herbicide is selected that has good activity on the weed and if the correct formulation is chosen.

Fall applications are best for post-emergent control of winter annual broadleaves, because at this time the weeds are still small just after germinating, and herbicides will translocate (move inside the plant) well. Spring control of winter annual broadleaves is more difficult because the weeds are larger and are less likely to translocate herbicide. Additionally, controlling winter annuals in the spring is not typically necessary as these weeds will complete their life cycle and naturally die at the end of the spring. Fall herbicide applications can also be effective against perennial broadleaves. 

Summer annual broadleaves and summer annual grasses are best controlled with pre-emergent herbicides applied in the spring before they germinate. Click here to learn all about the best timing for pre-emergents. They can also be controlled with post-emergent herbicides in early summer when the temperatures are cooler and before the weeds become too large or produce seed.