Yeah, some plants absorb co2 they use during their dark cycle, but marijuana is not one of them. It is classified as a c3 plant meaning it uses the co2 it gathers during the light cycle and does not need a rest (dark) period. So sayeth Ed Rosenthal

http://cannabisculture.com/articles/3127.html
Anathema2121 Reviewed by Anathema2121 on . Is this Safe???? 1st grow Ok so i started a plant early June, and now its about 1 M tall. i recently been watching to see if it flowers, and no luck so far. I live int he midwest, so i am not sure if the 12/12 is in effect. So today i did some research and saw what soem mates had told me about throwing a garbage can over the plant to induce the 12/12...... But my question is, Should I top the plant????? I am willing to cut the top off, maybe just the new nodes comming out the top? Not sure what to do really, just Rating: 5