2 month old plants, leaves turning yellow

[koin]

this is one of my three plants suffering from the same problem.

since germination, i've watered them regularly, and kept them in light.

at first i had them under 400 watt HPS lights, but due to some problems i had, i am now keeping them in front of a window to get sunlight every day.

the bottom leaves on the plants are turning a yellowish color, and after a few days they fall off. it keeps happening and it's slowly going up the plants.

i'm in northern US, so maybe the less sunlight is the issue, if so, i'll have to start using the HPS lighting again. i was thinking possibly they need bigger flower pots? the soil i'm using doesn't have any fertilizers in it, and i'm not using any nutrients at this time...just bottled spring water.

another thing, can someone identify whether this is a male or female plant?

[Ganja Guerrilla]

the plant maybe feeding on its self,

feed with a general purpose ferts start off @ 1/4 strength

go back to your 400 HPS the plants arent getting enough lite, they are streching

also consider topping the plant

[koin]

okay, i took your advice and my plants are doing great. i have a new question

they're in a small room with the 400 watt hps on them again, and i'm pruning the nodes when possible. i'm using a weak liquid nutrient solution i got, once every 1-2 weeks (i was doing it every week and the leaves started turning brown and spotty, so i lowered the dosage and it stopped happening).

so i have the 3 plants under the same light, now they were originally under 24/7 light until i had them in my window, then they had regular ordinary sun light. but now i have them under 24/7 HPS again, this is okay right? we've come to the conclusion that 2/3 are definitely female, and the other one we're unsure about. will these just start budding on their own? or will i need to do 12 and 12 again in order for them to bud? (keep in mind these plants experienced 12 and 12 for about 1.5 months next to my window)

other question:

i just germinated 2 new big bud seeds, and planted them in pots in soil and they just sprouted today...i have them in the same room with the other 3 plants so they can get the 24/7 light. i'm wondering if i can just leave everything in there for 24/7 until the new ones are ready to bud, then all at once, do 12 and 12 so they all bud at the same time.

will i hurt the older ones by leaving them at 24/7 while they are waiting to bud, or does it not matter?

i hope i'm being clear i'm trying my best, lol

thanks in advance.