i was wondering if adding a water mister among the plants would generate extra yield and or stronger plants.

If benefical is it better to have misters for vegetative state /or flowering stage /or both???

You mean to the foliage or the roots? For the roots, like aeroponics it's an awesome idea. For the foliage, I wouldn't be successful at it because the lights would burn the leaves, but maybe if you don't have a temp problem.

IF you mean running something like a swamp cooler, watch out!
During veg, in an area that is already quite hot and dry (less than 20%RH), it can be beneficial. You will have to exhaust all that humididty out of your room RIGHT at lights out though to prevent dewfall and potentially fungus. Pythium, verticulum, and fusarium wilts are VERY common in greenhouses.
In flower, add the danger of grey botyris mold (bud rot) and it becomes too risky to run a mister system.

So to summarize, unless you can guarantee that you are keeping your relative humidity below 65-70% at all times in veg, and below 50% in flower, especially at night, don't run misters.

__________________
"Careful what you carry- 'cause the Man is wise- you are still an outlaw in their eyes" -Steely Dan
"Multiple pieces of anecdotal evidence do not equal scientific fact." -Rhizome
"If the Queen Bee ain't happy... the hive isn't happy!"-Dutch Pimp
http://boards.cannabis.com/basic-gro...e-harvest.html<-It's a grow guide! Enjoy!
http://boards.cannabis.com/plant-pro...hy-how-do.html <- all the boring stuff about soil chemistry you never wanted to know
http://boards.cannabis.com/grow-log/...ml#post1837597 <-how to make canna caramels
http://boards.cannabis.com/grow-log/...ml#post1820481 <-illustrated cloning guide permalink
Contacting Her Dankness: stinkyattic at hushm4il-please use the same discretion you do on the boards, thanks.
I don't claim to know the first thing about growing anything; hell, I can't make a Chia pet sprout.

thanks people thats what i figured; it sounds like potential extra risk rather then a benefits