One of my flowerbeds has killer dirt. Nothing will grow in there, not even weeds or ivy. It's a raised bed with expensive topsoil I had hauled in. Every year, I add more compost and more mulch to the bed, trying to repair it. Finally, this year, i saw the first worm in it. My conclusion is that the field it came from had been sprayed with long acting herbicides over and over. Some of the research is saying even Roundup has a residual effect, even though the label claims it doesn't.
This fall, I planted iris, hosta and shrubs in the bed because I was needing space quickly. Hopefully they'll be ok and in a year or so I can use it as more than a holding bed. You would think any chemicals would be weakened after 7 years.....
I once saw a neighbor spraying a tree with brush killer, trying to kill off some poison ivy. The tree died too. The tree companies who removed trees and shred them have no idea if any trees have been exposed to chemicals like this, so I can see how one bag of bark mulch could have enough poison in it to kill a rose. Shredded up and made into potting soil, it would be even worse, I think.
