Pre-Emergent Herbicide

Category: science

A chemical barrier compound that stops weed seeds from successfully sprouting through the soil.

Pre-emergents do not kill existing weeds; instead, they create a chemical barrier layer in the top inch of soil. When a weed seed (like crabgrass) germinates, its initial root tip hits the herbicide block and dies instantly. Timing is critical: it must be applied before soil temperatures reach 55 degrees Fahrenheit.

Common Examples

• The technician calibrated the spreader to lay down the pre-emergent herbicide block right before the spring crabgrass germination window.
• Applying a pre-emergent herbicide will also block your new grass seed from growing; never combine this chemical with an overseeding plan.