What herbicide can be used to safely control broadleaf weeds in the dayliliy garden???
That would be difficult I think. But using a pre-emergent might work. I have done that. It works, but is expensive and requires updating.
Lots of people use Preen and Snapshot. Follow directions.
Early in the season, some people use 2 4 D to help control broadleaf weeds. I would spot spray, though, and try to limit the amount that gets on the daylily leaves.