Depends on the genetics. But generally, you want to stay below 85f to keep your buds nice and dense.
They can tolerate pretty much whatever on a short term basis. I had my fan go out once, box temp at 107, and they were happy as can be. But, if you're running Indica or Hybrid genetics, and are not running CO2, then around 75 is ideal. I shoot for 72, seems to be what my plants like best. But if you have to run at 80, it's not a big deal.
Also, outdoor plants are a bit different from indoor plants. They harden off quickly, and in ground their roots maintain a relatively stable temp. You have to remember that in containers, you're heating up that entire plant, and everything it takes in.
Edited by Sam87, 23 May 2010 - 10:59 PM.