I have heard that you can spread some pre-emergent in the flower beds the control weed seeds from growing. Is that true and what brand do you use. Also, how often do you apply it and how long will is last? I have 8 years as a lawn maintenance service and would like to get an app licence to add more services to my company. I am trying to take in knowledge of the chemical side of things in advance. Thanks for your replies in advance.