The clock is ticking on planting bearded iris. I doubt you have time to smother the weeds in the bed before the iris may not be established for winter. The bed really should have been dug up right after the iris currently there bloomed, with the new iris being planted about now.

The problem with waiting too long to plant iris isn't that they can't handle winter cold, but that they won't have the roots necessary to manage winter wet. So it is much less of an issue in places with dry winters, unlike Virginia.

I agree- for this plan, you should plant irises next year. If you till the soil and remove the weeds by hand, you can plant this year. Some places are no longer taking orders, though.
Renee