- Pre-emergent herbicides block weed seeds from germinating. They will not kill weeds already up. Use the fertilizer schedule to have a healthier yard, ultimately the best defense against weeds. Period.)
- Once a weed is up, you need a post-emergent herbicide. For example, a broadleaf weed control for clover.
- There are different forms of post-emergent herbicides. Some are "selective," and some are "non-selective." Glyphosate herbicides (Roundup, Eraser and organic vinegar solutions) are non-selective — they kill every kind of weed or grass. Selective herbicides usually target a specific category of weeds - broadleaf, grassy or sedge.
- If you're late with the application of pre-emergent herbicides, you can still do it. You just may not get total control, as some weeds may have already germinated.
- Observe any temperature restrictions of selective herbicides. For example, we now have cool-season herbicides for broadleaf weed control. We didn't have that 30 years ago. And we don't used products like Image when it's too hot.
- The powdered organic Garden Weasel AG Crabgrass product from Agra Lawn was originally designed for grassy weeds, although it can control a few broadleaf weeds I have had personal success with it on Virginia buttonweed.
- Nutgrass and nutsedge are neither grassy nor broadleaf weeds. I recommend sedge controls for those.
- The granular version of Bonide Weed Beater Complete is a real one-of-a-kind product — a pre- and post-emergent herbicide in one bag. The "pre" is essentially Barricade, which blocks broadleaf and grassy weed seed germination. But the "post" only works on broadleaf weeds.
- Surfactants are neither applicable nor necessary for granular pre- or post-emergent herbicides.
- Surfactants should be added to pretty much every liquid herbicide so the treatment actually sticks to the weeds.