Plant evaluation please

Sorry for the low quality image, it's not with my camera, I'll get my camera back in a couple of days.

Notice the lower leaves are getting yellow?
Well it's happening again, which is why the three bigger ones are mostly stem.
Any suggestions?
I've got superthrive, Vigoro All Purpose Plant NPK=24-8-16, Ultra Vigoro All Purpose Plant food NPK=12-5-7
Any suggestions?

can i just say that all your plants are stretching to much "even the small ones" what type of light are u using ?i would move it closer to the plants. as for the yellowing leaves its either nitro def or those leaves are not receiving enuff light, what sort of dosage have u got them on ? and how often do u feed?

Yeah as smallclosetgrower said your plants are stretching too much move the light closer and get a fan on them to strengthen the stems

Definitely a lot of stretching going on. What is your lighting setup?

Agreed.

Not enough light, and they're hungry as well. A healthy, well fed plant won't drop its lower leaves until the canopy shades them out, completely, or during flowering as the plant concentrates all its energy into buds.

I've got two florescent 24 In grow lights side by side and two 60 w plant grow lights on the bottom. And I'm trying to get an HPS 150 ballast, until which time I'll upgrade.
I feed about twice a month, I'll lower the lights. The seedlings are looking really good, since they're so close.
I've tried giving them some extra N, but I don't see that it's having any effect on them.
Will more foliage grow from the stems after I start flowering?
They've been growing extremely slow, the three are coming on there second month of vegetative grow. I was thinking about waiting another month before I put them into flowering.