Seedlings cotyldons and leaves turning yellow/brown

I bought a cabinet from Lowes that is about 24"Lx16"Wx70"H, it's perfect for my situation because it will be going inside of my closet to keep hidden but it seems to be getting too hot outside of the closet let alone when I put it in.

I have a 250w HPS with a 4" vortex fan (170ish cfm i believe), started at 12" away then moved to 15". I do have a fan controller on the vortex because that fan is way too powerful and loud for such a small cab. Also have 3 1.5" holes and 2 1" holes at the bottom for intake. Also a 120 mm computer fan blowing under the light and for circulation.

My temps are always between 84-90 with 20% humidity, and before I built my cab the seedlings were just under my 250 watt for 5 days at probably 100 degrees, which is what I kinda think the problem is but it seems to be getting worse and the plants seem to have really slowed up.

Anyways my problem is that the Cotyldons turned yellow a couple days ago on all 5 of my White Widow seedlings and the leaves started to brown on the edges, some worse then others. Only 1 seems to be quite healthy other then it's pretty light green. I have grown in the past and by the time 10 days rolled around I was already look at a couple nodes and these guys have barely started to go.

I really don't think I need to give them fertz at such a young age so any help would be appreciated. They are almost bone dry right now and the lights are out so i'm going to water when I turn the lights back on, any suggestions would be helpful..

Thanks guys

Your plants probably took a couple hard knocks from the 100 degree week, but it sounds like you're taking the right steps to get them well again.
Try putting ice in front of the fans. As the ice melts it'll give your babies extra moisture, and lower the temps. Don't forget that Marijuana is happiest in the mid 60's temp range.
I think they'll pull through just fine, make sure you water thoroughly.

Does anyone know what that yellowing is in the last 2 pics in my first post?

Well your cotyldons are supposed to die off now, and you should feed em lighty..1/2 strength.
The dead patch on the leaf looks like heat burn,stress- 100degrees is to hot for the tiny youngen`s try to cool the cabinet somehow, maybe mist a bit to cool em off, but watch the light does`nt burn em worse.
What is your light schedual[sp] right now?
ccb

mid 60's?....WHAT????? try mid 70's omg....72-77 is PERFECT...it's ok to dip into the 60's at night but high 60's at that

They seem so young to start giving them fertz, but I guess if the problem persists then I will start giving them some fish emulsions on my next watering. I've got my temps to be about a steady 85-88. I just can't seem to get it any better then that. I think the main problem is that the cabinet exhausts into my room and heats my room up even more and it just keeps getting hotter. I was thinking about running some ducting hose from the cab right to my window, but would 10ish feet of ducting hurt the fan? Should I try some CO2?.. Never used it so i'm not sure how it works.

My light schedule is about 20/4 right now, i'm trying to give them some night time to cool off from the heat.. otherwise I would be 24/0.

Hey guys I opened my cab when I woke up and the temp said it was 93. I was shocked, and one of my little guys is doing horrible. Here's a pic, almost everything is turning yellow, does he need nutes or is it all from the heat?

it looks dead...no nutes for about 2-3 weeks into grow...your light must be wayyy to close or its just not getting watered..plants that young should not need nutes yet.

It's only on Day 11 I think. My 250 watt is about 13 inches from the tops of the plants and I got 2 computer fans blowing in there. It does seem to be deterriating, the others aren't as bad but seem to be catching up at a slower pace. I have a fan pumping air from outside into my room and the temps are going down to about 84-87 and it just doesn't seem to get better then that.

get your temp in the 70's, 80's are too high

I went and bought a humidifier and it got my humidity with the lights on to about 30%, and my temp gets to about 81. I think 3 of my babies are lookin better, but 2 of them look like there dying. I couldn't just sit around and do nothing so I did give them a small dose of fertz. I mixed a half teaspoon of Alaska Fish Fertz in a half gallon and gave them each a half cup to drink. They didn't seem to mind it (the healthy ones seemed to like it actually) so i'm thinking that might have been one of the problems, it's just so crazy to me considering there so young. I always used to start giving them fertz on week 2... That one seedling is almost dead though, but i'm not gonna give up on it just yet!

if u can u should really try n run an exhaust line out the window, get that hot air out so it just sucks in air from ur oom or closet. that wut i had to do it dropped my temps from nineties to a perfect AND steady 74-77

Yep I think that's what i'm gonna do, I can just roll it in and out when I need to..

I've been really trying to figure this out and I think it might be down to either my PH or the soil had too much premixed fertilizer in there that burned em (which would suck considering I gave them a little fish fertz). I went out and bought a water purifer to water them with so hopefully that will help. I'm not sure if anyone heard of this type of soil before but it was givin to me brand new after my buddys old grow cause he didn't need it.. it's called: Whitney Farms Life Link Potting Soil, heres a link to it: Whitney Farms Organic Garden Products - Potting Soils .. maybe it's not good for seedlings?

That first pic is of my worst one, it's almost completely yellow/brown now and that 2nd one is my 2nd best but it's startin to look bad. Is that brown on the edges nute burn?.. if it is i'm going to flush her. Just trying to narrow this down because at this rate all my babys are gonna die.

Try ducting cool air directly from outside into the cabinet and reduce lighting time to 18/06 to lessen heat build up. Increasing rate of air flow going in/out of cabinet will help also help. Don't let heat build up in room, make sure you have sufficient ventilation 24 hours a day.

Get the lamp higher NOW I would say... more humidity too..

I've started to have a fan just blowing air into my room and with the cabinet about a quarter open the temp stays at about 74, and the humidity at about 35%. Without the fan blowing cold air into my room and with the door closed it gets up to 99 with 16% humidity.. just amazing how much of a difference it is. And with the cabinet closed and with cold air being blown in the average is 84, so not too bad if i need to go stealth for a while. I think when i get an exhaust hose going from my cabinet to my window i'll be set. Oh, and I am at about 19/5 for my light schedule.

Good news though, 3 of my babies are completely healed and growing again. The other 2 are still trying to go but it's not lookin too good. There still drinkin water and growing very slowly but I think i shoulda just gave them fertz like the other ones instead of flushing them, thought it was the best idea cause they were really messed up.. almost completely yellow/brown and I thought they were already dead.

Morning Pazzo.
Just read the link you put up and yes, your soil might be the problem.
Not that it`s bad, it`s just that it has Kelp meal & Bat guano... very fast acting, sometimes very hot, and wee seedlings can`t take that to early.
Hope things are better now, not sure what to tell you to correct it though.
W.W. is a very fussy strain to grow in the first place.
Good luck.
ccb

Well it looks like i'm back in business. One of them is kinda gone but it's still trying to grow. I think it was either the heat or my PH that caused most of the problems, but either way there both fixed. Here are pics of all 5 of 'em...

I agree...mostly. however, dark/evening temps are totally suitable to 55F, and actually the plant during maturation, prefers that.

homegrownboy said:

mid 60's?....WHAT????? try mid 70's omg....72-77 is PERFECT...it's ok to dip into the 60's at night but high 60's at that

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