There are Iris that bloom at different times of the year....what is the name of the ones blooming now. And what has your weather been like in the last few weeks, that will have a bearing on why they are blooming now.
They are the standard purple iris that flower in May. They were transplanted and pruned in summer and probably due to very wet autumn, they are now sending up flowers.
My unnamed purple ones bloom in March, but then I am many miles further south on the globe than you are so there is a great temperature difference. I don't transplant until early Autumn, if they need to be thinned out. And there are some Iris that bloom once in Spring and then again when the temps are cooler in Autumn. Or you just made them happy by transplanting them and they are thanking you with gorgeous flowers to enjoy. Plants do have a mind of their own sometimes.
Odif I have plants that finish for the year...ready to flower next spring flowering now...I just hope they flower at the time they should next year
