You brought up an interesting (to me, at least) point, MaryAnn. How late, is "too late" ? I'm in zone 5a, and, as far as "losses due to heaving" over the winter, on average, I would say irises MUST be planted , no later, that mid September (and Sept. 1st is better !). To increase the chance of bloom , if not 'in the ground" by August 1st....no matter how large and healthy the rhizome is...I can say only 10% will produce a flower the next season, If planted by July 1st, I'm in the 60%-70% range, and, if planted "immediately" after bloom is finished, I'm in the 90% range . It's pretty hard to get "shipped in" iris that early, but, those times I have, they took off like gangbusters !
