What's this messing with my colas?

Can anyone help me figure out what problem/deficiency is messing with my crop. The cola to the right with the yellow leaves and the reddish/brownish spots. It's only really affecting a few of the upper colas. The bottom growth grows in well, all green, and the buds look sicker than the tops! All in all they seem to be progressing more or less. It's been 8 weeks since I hit the switch. I have been feeding tiger bloom and big bloom @ 3 tsp each per gal every other watering. I give 1 gal each. Light is 600w hps. Temps remain around 72-79F. FFOF in 5 gal smart pots. Ph was @ a low of 5.8 about to weeks ago but now I keep the runoff @ about 6.8. Any help would be welcomed

Calcium and magnesium

ChaosHunter said:

Calcium and magnesium

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Thanks for such a speedy reply. Can I buy the kind that they sell at the vitamin shop for humans the liquid kind? Or do I need to try and find plant specific

You should always have a bottle of Calmag on hand. Plant specific.

I recommend Botanicare cal mag plus but im sure any cal mag would do.

ChaosHunter said:

You should always have a bottle of Calmag on hand. Plant specific.

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Why?
In grow in coco and never use calmag even though it's the first thing most coco growers use. If you use a nutrient that has everything in it to begin with there is no need for any additives.

I have yet to see the cannabis fertilizer with enough calmag in.

ANC said:

I have yet to see the cannabis fertilizer with enough calmag in.

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Floranova Grow, 7-4-10. Everything a plant needs from start to finish.

It doesn't say how much is in there.
If I had to guess, it would be in the 0.5 to 0.8% range like everything else.
Cannabis, unlike most plants, is a Mg whore.

ANC said:

I have yet to see the cannabis fertilizer with enough calmag in.

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Vitagrow

xtsho said:

Vitagrow

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Is that a veg nute or flower or both? This is only my first grow so I haven't had enough time/runs to experiment and check the effects of different nutes. IN MY OPINION the fox farm nutes thru veg and flower seemed to serve me well. Besides some yellowing, and ph problems, compared to other ppls plants "problems" I have seen my look great. I was thinking of DEFINATELY adding some calmag for next run but if there is some nute with enough in it then great

TheVitagrow at least matches the N in mg. Looks better on paper than many of the others.

ANC said:

It doesn't say how much is in there.
If I had to guess, it would be in the 0.5 to 0.8% range like everything else.
Cannabis, unlike most plants, is a Mg whore.

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https://www.1000bulbs.com/pdf/gh-gh1622-label.pdf
Sure it does. Its 4% calcium and 1.5% magnesium. Which is pretty close to the 3:1 ratio we are looking for. More than enough of both for the majority of cannabis strains. Or most any other annual as far as that goes.

Just curious but if the OP starts using the suggested Cal/Mag doses and this discoloration is still present in a couple weeks, would you say still not enough Cal Mag? Or would that be indicative of another issue?

Mass Medicinals said:

Just curious but if the OP starts using the suggested Cal/Mag doses and this discoloration is still present in a couple weeks, would you say still not enough Cal Mag? Or would that be indicative of another issue?

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Excellent question. Especially for a noob lol. It's not ph, my runoff is constantly 6.5-6.8. I don't think it's heat or light stress. The atmosphere around each cola is real comfortable to the hand. If it's not cal/mag def then what else would you guys suggest it to be. Arm me for the next battle lol

Well we just ask because personally, we are also newish and are harvesting a crop that had been pH balanced for coco coir, light and temps were good, and we did feed with cal/mag at every feeding even during the off nute days.

Stink Bug said:

https://www.1000bulbs.com/pdf/gh-gh1622-label.pdf
Sure it does. Its 4% calcium and 1.5% magnesium. Which is pretty close to the 3:1 ratio we are looking for. More than enough of both for the majority of cannabis strains. Or most any other annual as far as that goes.

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Thanks I will add it to my records.
I am quickly starting to learn that this hobby repeats the exact same shenanigans as the planted aquarium fertilizer trade.
They will sell you a bottle that is 90% water with a few grams of fertilizer salts in for a fortune.
What happens in the aquarium world is there are now individuals selling mixed or pure smalle scale fertilizer salts of high quality at low quantities and price.
I have a bit more work to do but I reckon I could put a mix together rather cheaply that is tailor-made for our coco, water and grow cycle.
Speak fertilizer to someone in the hobby and he is not even going to reply until you at least go out and measure the hardness of your water.

Mass Medicinals said:

Just curious but if the OP starts using the suggested Cal/Mag doses and this discoloration is still present in a couple weeks, would you say still not enough Cal Mag? Or would that be indicative of another issue?

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If coco coir was not properly buffered, it may be up to 4 months until it stops stealing your calcium and magnesium and kicking off Na and K in high quantities.

IMO the easiest way to buffer coco is with the addition of EWC. A heaping cup per gallon of medium. I use Black Magic coco mix from Home Depot. EWC is the only thing I add to it. From the bag it's nothing more than washed coco and perlite. And Floranova Grow is the only nutrient I use. The biggest thing you need to keep in mind is to vigorously shake the bottle each time you use it. My well water is about 320 ppm @ 7.4pH. I never use pH up or down. I let the EWC keep things in check for me.

Yeah I've seen some nice grows using only that and calmag and maybe epsom salt in place of that in late flower when the buds need to fatten.