generally speaking ....

most likely ... you will not get flowers..

but then they ought to be huge next year ...

by planting in fall.. you are giving them enough time to grow the requisite root mass to support those huge flowers ... by starting this spring.. by the time they get the roots.. it might be too late in the season.. especially for me in z5 MI ...

how that might all work for in z9 .. i will leave to others ... since your season is probably 4 months longer than mine ...

just never forget that the plant has to grow the roots for the flower .. and you will understand much about your expectations of flowering .. and why planting at a certain time might be important ..

ken

You can plant the rhizomes in the spring. If they are big with lots of green on the leaves, and if they are reblooming types, you may even get a bloom this fall.
You can also buy them already potted up at nurseries and if you plant them carefully, they will bloom this spring.

Most online sellers will not send the rhizomes out until August. If you see iris rhizomes at Home Depot, etc., they were harvested last year and are completely dried out now. They may come back to life or they may not. I would avoid buying those and wait until August when fresh ones are available.

Renee