What do you guys make of this problem?

Strain is Blue Dream in soil
1/2 FoxFarm and 1/2 ProMix and perlite
400 watt HPS
temps on the colder side ( High 60's to low 70"s) Its damned cold here.
I just fed it a half dose of Cal-Mag before this appeared.
Otherwise DynaGro Feed every other feeding
I dont mess with PH meters, I ( until now maybe) never had much problem like this

Sry...its cold damage

Diabolical666 said:

Sry...its cold damage

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Think ? My growrooms in my old basement and its really hard to maintain temps when the high outside is like -5 F Really bad timing too cause I just flipped them about a week ago and all 3 of my plants are not looking so good.
But it also looks a little like Potassium lock-out. I think anyway.

I kinda thought that at first because the spotting...but I worked with lots of tropical plants back in the day and this is what they looked like after being really cold.. Black edges. I use the FFand promix soil also and never seen FF do anything like this so thats why I ruled that out immediatly. Is your 400 air cooled?

Diabolical666 said:

. Is your 400 air cooled?

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Nah they're just 2 Easycool glass hoods. I use a small osculating fan in the room on a timer too. The rooms about 8x7 x 6 high where I use 2-400's with just 3 plants this run.

ok jw...so they are keeping the room semi warm.Id get a little cheapy heater, seems like you got some drafts.

Considering it's so cold, could it be a phosphorous deficiency? The calcium nitrate in cal-mag+ also works against phosphorous availability.

It must be getting pretty cold in their at night to cause that, I'd suggest a space heater in the room at night.

churchhaze said:

Considering it's so cold, could it be a phosphorous deficiency? The calcium nitrate in cal-mag+ also works against phosphorous availability.

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I wondered this too since it was shortly after I gave them some CalMag right around this time like I always do. Things seemed to go to shit not long after. Even in darkness time my temps never go below the 60's tho. I know thats not ideal but I didnt think it would cause this. Still, I went ahead and added a space heater on a timer. I just hate using them things when I'm not there to watch it. I have it on a timer with 1/2 hour off and on hoping it wont overheat or anything. I'm paranoid as hell about fires.

So, if I wanted to bump the phosphorous a little bit what would be the best or least lethal way to add some ? Opinions ?

Thanks guys, ( and Girl )

For soil or potting mix, you could use monopotassium phosphate or superphosphate (monocalcium phosphate). 1 gram of KH2PO4 per gallon of water is enough to completely supply phosphorous.... so use less than that.

Cobnobuler said:

So, if I wanted to bump the phosphorous a little bit what would be the best or least lethal way to add some ? Opinions ?

Thanks guys, ( and Girl )

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Are the pots sitting on a concrete floor? That's a nono if your in cold climates. It's the root balls temp that's doing the damage. Even an electric blanket (done safely and smartly) as a floor covering can help.

I'm not sure upper 60's/lower 70's is cold enough to lock out P. My flowering room pretty well stays in the 60's all during winter and I have no issues.

I have 2 HSO Blue Dreams in flower now and it's not unusual for my night time temps to be in the mid 50s' and I don't have that problem. I can 't say at the moment because it's my first run with it but I think it will be culled out of my garden.

SirSteely said:

Are the pots sitting on a concrete floor? .

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I've always had 3 inch thick insulation board wrapped with panda film. I always considered the cold coming up from the concrete floor and this time of year, its damned cold.