When I've divided my German bearded irises before in September, they would always bloom in the next spring. This year, not only did none of my irises bloom, the rest of my blooming bulbs didn't either--like Erlicheer, Sir Winston Churchill and Leucojum. I didn't do anything differently. We had maybe a cold couple of days in December, but that was it as far as extreme weather. My question is, is this normal for plants like this to have ups and downs in blooming? Thanks.