Yellow Leaves?

Hi , Im . my first grow, i got 11 white widows in my vegging room. Theyre 3 week old, and up to now have looked healthy and thrived. I know the first leaves will drop off, but quite alot of the bottom leaves are turning yellow. It is very warm in the cupboard, have a small fan with no extraction (only in the flowering room ie tent) and its about 32 normally. I have a 250w cfl that ive had on 24 hr, up til now, however i changed it to 20/4 from 2day. Someone...anyone help me out! Am i worrying over nothing?

i had some plants that did the same thing i dont think u have much to worry about. when mine did it they turned yellow and i just let them be and the leaves just slowly started to die but the rest of my plant was heathly. its ok for some leaves to die.
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Looks like a nitrogen deficiency. What kind of soil is that? They shouldn't have any defs that young in soil like fox farms that comes with enough nutrients for a couple months or so. If its good soil it could be a PH issue locking out the nutes. If the PH is too high or too low the plant can't absorb all the nutrients it needs and starts showing deficiencies. Personally I would consider transplanting into some larger pots with some fresh, good soil. Good luck!

Yes i would go with they need to be fed, but could be some underlying culprits too..Like wells said providing more info will help on being able to determine whats the problem

Hey,,before you start adding nutes those plants dont look def. They look root bound from those pics,,I would have those plants in larger containers by now,,thats why its your tips,in the top left 3 pots have bleached like that,,its not a def. Its root bound, they all are,, the veins of the leaves would yellow too if it was an N def..so try transplant and if in a week they arnt growing then its a def. I have had root bound plants and there leaves bleach like that, so there my reasoning behind my answer.
Take it easy.

P.S. try slipping one or two of them outta the pots to check if they are root bound, if they are the roots will be matted at the bottom, and also will 'spiral' round the bottom of the pots...take it easy.