and ...... why are my iris blooming again in late autumn (2023)
You will have been sent a planting guide with your order. IT CLEARLY SHOWS YOU WHERE AND HOW TO PLANT YOUR IRIS RHIZOMES. There are also other blogs below that will illustrate this for you. We have been growing iris for a long time, so take a professionals advise, please don't follow the recent Gardener's World advice to bury rhizomes.... they will rot.
So: why are my iris blooming again in late autumn (2023)
In winter most iris rhizomes look pretty dormant until spring, all the activity will be going on underground with new roots growing. Some new leaves may start to grow.
IF there is any flowering at this time of year (autumn) it will be the re-bloomers. They normally flower once in May/June then again in Sept/Oct.
However, normal seems to have disappeared both from our weather and plant growing cycles. We are finding that some varieties are re-flowering at very odd times of year. The recent spring-like temps together with day lengths, similar at this time of year to spring, that blooms are forming.
What to do with very late autumn or unexpected re-blooming iris flower spikes?
Reblooming iris: let it flower. It's up to you if you want to cut the flower pike ( at the base) and take it indoors to enjoy the bloom.
IF the flower spike is hit by frost, cut it off at an angle, to prevent water/rot travelling down to the rhizome.
Non reblooming iris: IF there are a number of fans formed from the rhizome, let the flower spike form. When you see the first colour appear, cut the whole fan to the base (at an angle to prevent water and rot travelling down to the rhizome). Take the flower indoors, it will open in a vase of water.
Some customers are choosing to dig the flowering rhizome and pot it up, cutting off the flower spike. The plant then needs to go in a greenhouse or cold frame and we kept damp not wet. Water only when the soil is bone dry. Then replant in spring when the soil has warmed up.
Watch the overall rhizome and leaf fans in general as the flowering takes a lot out of the rhizome, to the point that it will have 'done its job' (ie flowering) and so will die back and new offshoot rhizomes will start forming for flowering next spring.
With the terrible wet weather it's rot that will kill your rhizome. They don't mind cold.