Question
Tom
I read your answer on how to grow iris from seed i just wanted to ad a little to the question. When should you plant the seeds late fall?
Thank you
aaron

Answer
Hi Aaron,
Thanx for your question. If you want to plant the seed in situ (which means out in the garden), you should do so anytime in the fall so that the seeds will have time to vernalize and break dormancy.  Other terms for vernalization are stratifying or stratification or cold treating/treatment.  What that means is the seeds must be exposed to first, a cold, damp environment. And then a warm, damp period.  The cold period activates a hormone that keeps the seed from germinating at the wrong time.  When it warms up the hormone is activated to induce germination.  Many seeds just need a couple of months at temps consistently below 40篎.  Other seeds need several seasons of alternating cold and warm periods.  Iris seeds, in my experience, generally just need a couple of months of cold treatment to break dormancy and then they germinate rather quickly once it warms up.  So, if you plant them in situ in September, they will emerge after the last frost and the ground warms up.  Be sure to keep the garden bed free from weeds.  The irises will look like grass when they come up.  It usually takes the second or third season for blooms.  You can start the seeds in the fridge in January or February for a spring germination if you prefer to monitor your seedlings that way.   I hope this helps.
Tom