I don't pre-em grow in eiither. When pulging St Augstine grass we just let the weeds go until they need post-em. Pre-em will slow grow in. St Augstine grows from runners and if the runner can not put down roots they don't grow as fast. I only use Pre em on Crab grass or real problem areas. Like Stone says a health turf is its own defense against weeds. If I have a nice where weeds can get in I try and plug that area. Of course warm season turf is different than cool season turf but I think the theory is the same. I do pre-em my planting beds if they are real wet and I have a problem with weeds.
"TG doesn't give a rats ass about being "Responsible" as long as sales/production quotas are met. That's it in a nutshell. A recipe for disaster IMO." Ted Putnam 2/28/14
You can lead a Donkey to water but you can't make the Jackass Drink
"As Americans you have the right to be stupid." John Kerry
"Life is tough, but it's tougher when you're stupid.” John Wayne.