Lately, if leaves blow into the beds I leave them there over winter, but remove them as soon as the warmer weather returns in the spring. I've done this because for the last few years, we have not had snow cover here that lasts all winter, and this year we keep having weather that is in the 40's one day and the teens the next. I'm hoping that the leaves will help hold the temp of the soil at a constant. I've heard of some people who use pine needles to cover them over winter. Many people cut the foliage back in the fall, other's don't. I've heard that the leaves return nutrients to the rhizome when they die back, yet I don't think it really matters much. Cutting the foliage MAY get rid of some of the iris borers eggs if disposed of properly. Some people burn off their iris patches in the fall, but not everyone can do that, and if you have mixed beds, it's a bit hard to do. I tend to think that irises do well in spite of our interferences.
