Pre-emergent Herbicide—It really works!
I'm officially converted to the power of pre-emergent. You can go organic or synthetic, but if you have a major weed problem, pre-emergent herbicide is the way to go.
Pre-emergent: The Extra Octane in your Lawn Care Plan
I'm primarily converted to pre-emergent herbicide as an effective weed-control strategy for landscape beds. I moved to my current town to manage horticultural operations at a botanical garden. The weeds there were, literally, smothering all life forms throughout the entire garden. And, we're in the South. The South is where invasive plants go on vacation and never leave. We also have-surprise!-two seasons of weeds: winter and summer.
There's no possible way to get a handle on a weed problem without intervention. There aren't enough man hours in the day to pull all of the weeds. There's not enough newspaper to smother them. The only way to regain control was pre-emergent herbicide. Once we started using it, the weeds stopped coming. It seemed magical at the time, because the weeds were such a frustration.
How to use Pre-Emergent Herbicide
There are basically two types of pre-emergent: organic and synthetic. I'm a fan of the organic method, which is, essentially, corn gluten. You can now easily find corn gluten or organic pre-emergent products for sale at most home and garden stores. Pre-emergent works by preventing weed seeds from sprouting. (It doesn't kill existing weeds. You still have to pull or spray those to get rid of them.) Corn gluten gives you double for the money, too, by giving your lawn a natural nitrogen boost.
You have to apply pre-emergent ahead of the season for which you want to kill weeds. In cooler climates, that's March or April for summer weeds. In warmer climates, that's February for summer weeds and August for winter weeds.
If you use a granular synthetic product, you need to water the lawn thoroughly after applying it so that the chemical can break down and go to work.
Remember! Never use pre-emergent where you're planning to plant a new sod or seed lawn. The pre-emergent herbicide will prevent the new lawn plants from growing.