Wondering if anyone uses Preen. And good or bad?

I do. It has been a big help. I try to get it applied right before an expected rain so it gets watered in.

If I understand the literature correctly, 100% organic Preen is simply corn gluten which binds with and coats seeds to prevent them from sprouting. Most other Preen products contain trifluralin, an herbicide that is highly toxic to aquatic wildlife. Some contain isoxaben, 2-4-D, mecoprop-p, dicamba, and/or dithiopyr. You'd have to research each of these chemicals to determine your comfort level using them. I've never used Preen, so can't speak to its effectiveness.

Careful, you won't be able to eat the bulbs if you use chemicals!

Deb, the Preen Vegetable Garden Weed Preventer sold on Amazon and labeled Organic:
https://www.amazon.com/dp/B000I1R2A2/
says in the production that Preen Vegetable Garden Weed Preventer contains corn gluten meal but does not list any other ingredients.

Mac, one of these days I will remember to include citations of where I find information. I got this NOT from a Preen site or vendor of Preen, but from somewhere I consider reputable. It I knew how to check my history, I could likely figure it out. But alas. Leftwood, I guess I don't 'get' your joke (?). Were we talking bulbs? Oh, this is posted in the lily forum. I don't follow specific forums, just threads that catch my eye. My mistake. I would still advise using caution as it appears there are several chemicals which may or may not be used in different Preen formulations and I'm always a proponent of less poison on the planet.

Deb, your research on Preen was very informative . I'm not surprised by how little information the sellers provide. And I'm all onboard with less poison on the planet .