Thank you all for the scientific comments. i will try to be more observant to my orchids' environment.
i have been searching what will trigger the flower spike for orchids, or do orchids have blooming season like roses... but no luck!
at least this orchids "rooty" one, is healthy like the my other orchids...
re. decrease of temperature during fall, i think it is hard to say... we just had " indian summer" last monday and tuesday (90's in the a.m. and 80'- upper 50's at night) and sudden drop to mid 70's in the am and 50's at night. too unpredictable.
But i am hoping this orchid is just adapting to it's new home. maybe the blooming time for her is "SOON"!!!