I doubt it. Yes, Preen is a preemergent which is what I want. To prevent the gazillion weeds (those that grow from seed - won't help for those that have roots beneath the surface) from germinating. But despite that as the soil is disturbed new seeds come to light and so it seems you need to spread it (being careful not to overdue - it seems to have a bad effect on garden plants if over used) in early spring, then after placing any new plants/annuals etc. And if you pull weeds, that moves the soil and potentially exposes more. Really a never ending process
