My three oldest plants (two are 5 weeks old and one is 4 weeks) are starting to droop. i know its not over watering because i wait tell there dry. I'm starting to think the pots are too small (6x6x6). The oldest one's bottem leaves are yellow to light green and feel rubbery.


two 70watt HPS

Have you thought about you might be under watering them? I have had my plants do just about the same thing when under watered. They were droopy even after I watered them. I started watering them every other to third day and she recovered. I'm not for sure this is the case with your plants but that sounds like what mine was doing when I under watered her.
Small pots dry out to quickly and after rereading your post, you are probaly root bound and this is causing your plants to have a double wammy effect on them. Small pots equals not enough water and root bound.

the first looked like a bit to much water but the last look like a a heat issue, are this MH bulbs up there, if this is the case they are frying your babies maybe, check if you can leave your hand at about tips height without getting burned after a minute or longer, also check the temperature in your grow...

__________________
keep the thumb green and the gun oiled, !

I keep the area at 75 Degrees. I have a portable A/C I keep on the ground level below the shelf to cool down the room. I also have an oscillating fan on the shelf with the plants to circulate the air and create wind.

Also, the bulbs are HPS, not metal halide.

It really can't be over-watering because of how dry I let them get between watering. I usually go several days.. I might even be underwatering like someone previously posted.

If you let them sit several days with out water I would say that is your problem.

HPS are normally not in the right spec to grow with in veg, if you not happen to have bulbs that are heavy in the blue spec.

since you water only every few days it really could be that you underwater them, adjust your water cycle with the size of the plant, the larger they get the more they need

__________________
keep the thumb green and the gun oiled, !

rootbound..definitely, look for any yellowing of the bottom leaves and slow growth, thats the next signs.

__________________

There's no way those babies are rootbound in those pots. I've seen bigger plants in 16 oz cups. They are a bit shallow, so they are probably drying out fairly quickly. I wouldn't try transplanting until you get them out of stress.

I would guess underwatering is your problem as others have suggested. Be carefull not to over compenstae though. Just give them a good watering and then water them again when the top of the soil get's a little crusty.

Also, I would back those light off a bit until they perk up. They won't be able to utilize all of that light until they recover a bit anyway.

P.S....

I realize this thread is years old, but people reference this stuff and when newbies see advice like this at that at the end of a thread they run with it!

Rootbinding is a problem you may see occasionally in a plant that has spent a long time in a small container and there is litterally no more room for root growth. Roots become entangle and grow in circles. It doesn't happen to 4 week old plants unless you planted it in a shot glass!

The below soil mass of a plant is normally very close to being an equal 50/50 in size/area proportion to the above soil mass of the plant.

Think about that the next time you see a large plant in a small pot and ask yourself how cramped those roots must actually be.
　
For some reason people do not understand or will not accept the root-bound condition.

Once a plant’s roots begin to circle its pot the plant is then under some degree of stress. The longer the circling is allow to go on the more the stress level increases.
　
Herb plants are very tough resilient plants that can not only survive but also at times do fairly well in less than optimal conditions. Just because a plant will do well in poor conditions that should not mean that the plant should not be given better conditions so it could then do even better for you.
　
I find it odd how some people will be so into maximizing their yield but then they limit their plants by growing in pots that are to small to allow their plants to be all they otherwise could be.



Root-bound:
Root-bound is where the roots of your plant outgrow the container they are contained in.

The following symptoms may be observed if you allow your plants to become root-bound:

1. Stunted Growth.
2. Stretching.
3. Smaller and slower bud production.
4. Needs watering too often.
5. Easy to burn with low % nutrient solution mixtures.
6. Wilting.

__________________
Do you know what "nemesis" means? A righteous infliction of retribution manifested by an appropriate agent. Personified in this case by an 'orrible cunt... me.