I quit using it.

I'm not entirely sure it would do any harm butterflies nectaring on flowers, perhaps someone more experienced than me can chime in.

That being said, I dug out some Blanket Flower (Gailardia) that was taking over my bed in the front yard to make room for a Flutterby Petite "Tutti Fruity" butterfly bush, and noticed VERY FEW worms in my soil! So I decided to hand weed because of that.

Mark

Did you know that Lebanon makes an organic 'Preen'? Its active ingredient is corn gluten, which has been used as a pre-emergent herbicide for quite some time. I've never used the 'Preen' product, but I do use corn gluten quite happily.

As far as using the standard (active ingredient Trifluralin) 'Preen', it won't harm existing plants (including weeds) and since it can be used in the veggie garden after the plants have come up and are growing, I don't see why it shouldn't be used in the butterfly garden.

I'm worried about the butterflies not coming to the flowers because of Preen's toxic ingredients