First Time Grower with questions

Alright so me and a buddy of mine started two plants about a month ago (I don't even smoke, haha) and up until about a week ago everything was great. Then he sent me a picture message and our largest of the two plants (about 1.5 feet tall and 8 inches wide) all of the sudden wilted terribly and I believe is now dead (I can't be sure as I am at school most of the time and my buddy takes primary care of them). Before its demise I noticed that the edges of the leaves became discolored. Not necessarily yellow but a lighter shade of green from the rest of the leaf rather. Anyway I may be answering my own question but, could this be do to possible shock I may have sent it into? In the course of one day we transplanted to plant into a larger pot, changed the brand of plant food we were giving it and changed the light cycle from 24 hours a day to 22 hours a day. I also noticed that my friend would pour the water into the pots rather than spray it on (as we had it in a spray bottle). There were drainage holes in the pots but could he have over watered? Have I answered my own question or could someone provide a better diagnosis?

yeah all that stuff you did in one day is to much and some is worse than others.

1:transplanying if not done gentilly will stunt or kill a plant on its own. if done properly little or no stress will be put on the plant. imop they are to big to transplant. i always transplant 2 weeks after seedlings break ground.

2:changing plant food isnt typically to major but be carefull when doing so, id do a complete flush before introducing a new brand of product.

3:theres no reason to change your light cycle to 22-2. not a good idea. your gonna end up w/ hermies if you mess w/ the light cycle to much. from when a seed breaks ground, until the 2nd week in the grow stage i give em 24 hours of light. 2nd week untill bloom, i give em 18-6. then 12-12 for bloom.

4:dont folliar feed (spray leaves) unless you have to, (via fixing difficiancies or later in the bloom cycle to give em an added kick.)

5: over wattering is pretty common, a plant that size should recieve aroun 3 cups of water every 2-3 days depending on the circulation soil drainage and lights being used

**what kind of set up are you running?? lights, nutes, water schedule (do you ph your water??), circulation.

i have a feeling alot is going wrong, the more info the better

Thanks all of that helps a lot....

In response to your questions, we are brand new to the grow scene and we're real short on cash so we really can't afford to buy all the expensive nutrients that I've found online so we were first using a miracle grow powder, but then switched to a liquid concentrated Shultz fertilizer that had a higher nitrogen content... As far as lighting goes all we had was one 18" cool white flourescent tube, but we are going to switch to four flourescent bulbs (2 cool white and 2 warm white) as we have just built ourselves a small grow closet (4'x4'x2'). Also, right now we're in soil but I have recently built a small aeroponics system and I plan on setting it up this weekend.... My friend was watering the plants every day, giving them probably a half liter or so (probably just a tad less)... As for air circulation that is also a problem as the two plants are/were in a cardboard box and the only air circulation they got was us opening the box twice a day.... I did purchase two small muffin fans for the grow closet though...

Also, I have not been testing the pH of our water but I did just get a pH tester, but it was only $10 so I don't know how accurate it will be