I've already hardened off my plants, cause I live in cali'...but I just wanted to give anyone who's just starting out a critical heads up. I put my plants outside in the daytime the 1st. 2 wks. in solid shade...then 2 weeks in mottled shade...then they're good to go for sure!...if you just take them from inside into the bright sunlight, they'll get sunburn. indoor leaves are too tender, and MUST be hardened in order to handle the punishing sun.
I think that's a pretty extreme hardening process.
I'm in Cali, just finished the hardening off process about a week and a half ago.
I did 3 days in total shade, bringing them out in direct sun for 2 hours each day. Then put them in a spot where they get 50% shade 50% direct sun for another 3 days. Then I moved them strait to an all day direct sun spot where they'll finish veging (I move them when they start flowering to avoid CAMP helicopters) Worked pretty well.
I had 20 seedlings (local unnamed sativa) and 20 clones (10 bubblegum/10 sour diesel).
Out of that I lost 2 seedlings and am close to losing 1 sour diesel. Losing 3 out of 40 doesn't seem that bad to me. I'm sure I could be super careful taking a month to harden off and it would save me maybe a plant of two but it seems worth it to get an extra 3 weeks of veging out of it.