Even local nurseries usually get many of their plants that are started by other companies. The nursery employees may or may not have any idea what's been put on the plants before they arrive in the nursery. I've found that it's very difficult to find out what chemicals have been applied to nursery plants. Ideally, starting plants from seed is best, but of course many people can't or won't do that. I do trust one local native plant nursery because I know the owner...their plants are safe to use. Another local native plant nursery does occasionally uses pesticides.