If you ran out of weed you should take one small cola and put the oven on a temperature lower than thc evaporates i think it is 280 but i'm not sure so look it up to be certain. And put it in there for 10 - 15 min maybe more but check it regularly when the outsides of the cola become crispy...
Usually when the lower extremities of your plant start to yellow it is due to a nitrogen deficiency. I know what your thinking OMFG i need to fertilize. Yes you do BUT be careful don't over fertilize its easier than you think. The plants will grow fine with some yellowing. But they will die or...