I've been growing in 20 percent humidity, with daytime temps ranging from 80-90 degrees most of the time. No CO2. As for being a successful grow, I'd say it's not bad for my first. I was expecting about 1-2 zips per plant, with 9 plants under a 600 watt HPS in a 4v4 tray. I would've likely gotten it, but the combination of forgetting to water, nute burn, heat stress, moderate fungus gnat infestation, and a weeklong flush to fix the burn (this all happened within weeks 4 and 5) slowed their growth a good deal. Now expecting probably...1-1.5. As far as the quality goes...when I reach through my canopy to water, my arms are sticky when they make their way out. They smell sweet, skunky, and have some of the most beautiful and dense trich formation I've ever seen, including pictures from magazines and whatnot(used a microscope ;]). So I believe it can be done.However...

DO keep in mind that I used a good deal of the Advanced Nutrients line.(expensive crud)

also...

DO be careful about keeping the girls(hopefully) hydrated. Extreme heat + not enough water = extremely unhappy plant (in my experience)