If you know your lawn is prone to weeds in the spring and summer, pre-emergent herbicide treatments will help stop weeds before they emerge. Pre-emergent herbicides form a barrier in the top inch or two of soil, preventing weeds from growing above the soil. This means less weeds to treat when the weather warms, keeping your lawn beautiful year round.
Pre-emergent herbicides are usually applied in the early growing season and help prevent target grass and broadleaf weed seeds from germinating as the weather begins to warm up in the Spring. A pre-emergent herbicide will create a barrier around a seed, making it nearly impossible for the seed to sprout and the weed or grass to grow.
When applying pre-emergents, be careful to aerate first, and not after applying the products. Aeration can break the seal over the ground and around the seeds which makes the pre-emergents less effective.
Pre-emergent herbicides can be applied using a granular spreader or a pressurized handheld sprayer. Most liquid herbicides come as concentrated solutions that need to be mixed with water first (according to the label) before application. Granular herbicides can be spread using a granular spreader and may require irrigation in order to help the granule release the pre-emergent chemical.