Agree with you Elaine..about that humidity factor..we do not have that here in my area..sadly...and I do not dare mist it either..the cuttings just do not like it..we get a fast cool down at night..so dry as it goes..
I do know Plumies are really tough cookies once fully rooted..have seen them grow very big and tall in my home country before..true veterans of floods and moonsoon rains. I guess that is why I got blindsided rooting cuttings, I forgot the equatorial humidity the plants get in my home country oh well......anyhow, learning as I go forever and ever..