Q: Most professional lawn care services in my neighborhood do a good job preventing weeds by spraying the lawn. My service used a granular product and they didn’t have good success. I want to manage my own yard but I’m having a hard time finding a liquid pre-emergent. Is this only available to licensed companies?
A: Liquid pre-emergents are problematic to apply because they are initially very concentrated. The chemical must be precisely mixed with the correct volume of water and applied evenly to control weeds. That’s why you see the professionals using tank trucks where the herbicide has been mixed by a specialist at headquarters. Granular pre-emergents are “pre-mixed”, if you will, because the chemical is uniformly combined with an inert, gritty carrier. I think you can get good weed control with granular products as long as they are applied correctly. Summer annual weeds are controlled by putting out a pre-emergent in early March each year. Be sure to follow label directions and irrigate the lawn immediately to dissolve the chemical into the soil. You can buy liquid pre-emergents if you care to hunt for them. They are not restricted-use pesticides but are simply very expensive because they are so concentrated.