How long should you wait before applying a pre emergence herbicide after new turf grass seedlings have been mowed?

The correct answer indicates that you should wait 3 to 4 times after mowing new turfgrass seedlings before applying a pre-emergent herbicide. This is crucial because pre-emergent herbicides are designed to prevent weed seeds from germinating, and applying them too soon after the establishment of new seedlings can hinder the growth and development of the grass itself.

After mowing, the turfgrass needs time to establish its root system and overall health. If a pre-emergent is applied too soon, it can affect the newly rooted grass, potentially killing or stunting its growth. Waiting the specified number of mowings (3 to 4) allows sufficient time for the seedlings to acclimate, develop robust roots, and grow strong enough to withstand any impact from the herbicide.

Proper timing ensures that the newly established grass can thrive while still providing effective weed control, balancing the health of the turf with the need to manage weeds.