cover new rhizomes in winter?

Hi friends. I have irises planted over the last few months and I've heard conflicting ideas about covering new rhizomes with an inch of topsoil or mulch through the coldest months then removing it early spring, or should I just leave them exposed... a few weighed in on another thread but I'd appreciate any others' thoughts on how best to protect these new babies. some look more vulnerable than others and it's finally getting cold.

thank you, shawna

I don't cover them but to prevent the heaving from freezing I've read posts where people say to place a brick on top of the rhizomes and remove it in April. Good luck!