chasv77answered grow question 5 years ago Hey there, I also grow in a semi (ha ha, some say desert) arid climate. I use grow cabinets, in dry ambient room humidity levels.
During the early stages of veg, my levels were always around 25-30%. This did not seem to affect growth rate.
After the plants get big, and more water is used, transpiration (evap of fabric pots as well) added 10% more humidity.
Unless the seed developer recommends a certain humidity range, it really isn't an issue to me.
As far as temp ranges go, I have gone from 80F to 65F, consistently with no issues,with all of my strains.
Some pundits say, no more then a 20 degree diff, between high/low. OF course some strains stop growing at certain low temps, so research your strain, and some grow tips for them.