Do NOT uncover your irises. This sort of mid-winter temp fluctuation is exactly why you covered them in the first place. If you keep them covered, the mulch will keep their surrounding soil frozen so they won't heave and/or crack with freeze/thaw cycles.

Remove the mulch gradually in early spring (March, maybe, in your area) when things warm up and growth starts under the mulch.

Laurie

Laurie, thanks for the reply. I felt very confident about doing just as you suggested, but on a walk around the yard yesterday I lifted the corner of the burlap and poked my finger in - I would say that there is over an inch or so of soil that is totally thawed out and the burlap is quite soggy. My concern, with no freezing in the forecasted future (we will hit 40 tomorrow!)and the moisture held against the rhizomes, that things may start to rot (or is it still just too cold for that to happen?) My thought was to uncover for air circulation until it freezes again, then I would cover them back up. I will do nothing though until I hear form more of you with your ideas!

Thanks again!

Well, the wet burlap is a concern. You really shouldn't have used that to begin with. Bearded irises should be mulched only with materials that allow free air flow and will not compact and/or hold moisture against the rhizomes - materials like evergreen boughs, straw, marsh hay, and whole oak leaves (NOT chopped). It would probably be best to pull that burlap out from under the straw and get rid of it, but leave the straw in place.

Laurie