The whole plant is yellowing

She looks different because she may be the only one that is over watered. Maybe the fan doesn't hit her tha same as the rest?? This looks otherwise healthy but the leaf tips pull downwards and shes different from the rest. Dont water based on schedules, water when the pot is dry and lightweight or they droop slightly

Kushash said:

Seeds are like brothers and sisters and some seeds might not be as vigorous as others, some might be Mg whores.
If it was my plant I'd take it away from the light and give it a foliar with 1/2 Tsp of epsom salt per gal of water and water some in the next time you need to water it. If it's Mg the plant will show an improved color about 4 days after being treated. I favor it being a Mg deficiency over N.

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Yes, lets not forget RO water needs to be supplemented with Calmag

@JimmiP I must admit that I have not noticed the fan pointing at the plant and that could probably be the problem too! tonight I will check everything meticulously and adjust the position of the fan and on the weekend, when I have more time, I will try to lift the pots off the ground a few centimeters. As for the temperature, the minimum is 22 and the maximum 24.5 but I can't raise it more than that without spending a lot of money on the bill. Thanks so much for the advice

@Alien GreenThumbs consider that I only water when I touch the ground and feel it is dry! it has never given me overwatering signals and consider that the air introduction fan points almost to the pot, besides the various fans positioned above and below, and as for the RO water I'm not using it yet! I only use it when I start with fertilizer.

@Kushash thank you so much for the advice! I will try to feed her and see how she reacts .. I was just going crazy since the others with the same parameters are fine

Blackketch said:

@OneMoreRip I checked the pH by taking a sample of earth and mixed it with water with neutral pH and I added 3 drops of liquid tester and, since the water was a bit cloudy, I couldn't define from the color if it was a 6 or 6.5 however for sure between a range of 6-7. the plants were transplanted 2 weeks ago in 17lt pots but in the meantime I will try to feed only the plant in question. Tonight I will check the ph pot by pot and update you!

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Maybe just check the best looking plant and the one giving trouble and compare two colors and make sure it matches. I have not used that that method for testing ph and can't really comment other than, I would just compare the color of ph test from the best plant and the worst one, to see that they match.

ph being in the correct range is very important for healthy plants. I mix my own soil now and use a $20 digital ph pen ('for liquids'), to test my soil ph and it seems to work very well for me. I advise a digital ph tester, they do make soil specific ones, I have had bad luck with the soil ph tester i got, others have not.

It could be a feed or water issue as well as others have said, just by looking at it, I cant say anything for sure. i believe if all of the pots seem to weigh the same, probably not a watering issue, maybe something worth testing.

Blackketch said:

@JimmiP I must admit that I have not noticed the fan pointing at the plant and that could probably be the problem too! tonight I will check everything meticulously and adjust the position of the fan and on the weekend, when I have more time, I will try to lift the pots off the ground a few centimeters. As for the temperature, the minimum is 22 and the maximum 24.5 but I can't raise it more than that without spending a lot of money on the bill. Thanks so much for the advice

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Is that a fan, or just a duct? If it's an intake fan, then definitely point it away from the air pots.
As to the temperature, a small space heater with an inkbird controller will not significantly raise your electricity bill. And the correct temperatures can definitely improve your yield.

Blackketch said:

@JimmiP I must admit that I have not noticed the fan pointing at the plant and that could probably be the problem too! tonight I will check everything meticulously and adjust the position of the fan and on the weekend, when I have more time, I will try to lift the pots off the ground a few centimeters. As for the temperature, the minimum is 22 and the maximum 24.5 but I can't raise it more than that without spending a lot of money on the bill. Thanks so much for the advice

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I have plants outside in near freezing temps, they appear healty, jsut grow slowly. you seem to be having good growth, I wouldn't worry about temps very much (for me, not at all).

Kushash said:

Seeds are like brothers and sisters and some seeds might not be as vigorous as others, some might be Mg whores.
If it was my plant I'd take it away from the light and give it a foliar with 1/2 Tsp of epsom salt per gal of water and water some in the next time you need to water it. If it's Mg the plant will show an improved color about 4 days after being treated. I favor it being a Mg deficiency over N.

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can you show me/us where different cannabis plants have different nutritional needs?

I also wouldn't add salts in my grow, from what I have read it can throw off balance in the growing medium. Just doesnt seem good to me. Pretty sure op already has nutes that he has used before with success, no need to add anything imo

OneMoreRip said:

sounds good, i'd compare the good ones with the bad one, regarding everything you believe may be relevant and you may find your problem. my only guess would be ph, assuming it has same feed as the others. maybe over watered if getting same waterings as others and you said it was smaller smaller.

ive never seen anything saying one cannabis plant has different than standard requirements for good health, but if someone has a link to info on that, I'd love to see it. Thanks

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Here's the guy with THE answer to every question and it is pH. Lol.

OneMoreRip said:

I have plants outside in near freezing temps, they appear healty, jsut grow slowly. you seem to be having good growth, I wouldn't worry about temps very much (for me, not at all).

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They're doing great because you know the pH of the medium and runoff pH. Right? Everything else is insignificant.

OneMoreRip said:

can you show me/us where different cannabis plants have different nutritional needs?

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Your assumptions should be pushed back a little. Pull back and see things from the big picture.

Almost no creature or living thing grows identically to another.
Diversity is how nature perseveres, the old survival of the fittest stuff.
Variations in genetics occur all the time.

The asssumptions you made about growing cannabis may not apply.
Yes it is true that all cannabis follows a general pattern.
But how each plant grows can and will be largely random, even if they have many common traits.

Point is...for commercial facilities they either grow hundreds of plants hunting for keepers.
Or they pay a lot to buy them and clone them to create identical copies.

Very few genetic lines are uniform with little variation.

ComfortCreator said:

Your assumptions should be pushed back a little. Pull back and see things from the big picture.

Almost no creature or living thing grows identically to another.
Diversity is how nature perseveres, the old survival of the fittest stuff.
Variations in genetics occur all the time.

The asssumptions you made about growing cannabis may not apply.
Yes it is true that all cannabis follows a general pattern.
But how each plant grows can and will be largely random, even if they have many common traits.

Point is...for commercial facilities they either grow hundreds of plants hunting for keepers.
Or they pay a lot to buy them and clone them to create identical copies.

Very few genetic lines are uniform with little variation.

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do you have anything scientific? I'm not assuming, I used to believe what you said before but the only scientist that studies cannabis, that I have come across, stated otherwise, from what l recall. and it ~makes sense to me as well. Not a big deal, just looking for something ~meaningful/scientific on the topic, been interested in it for a while

I was hoping to read up on it. thank you

labworld said:

PH can cause lots of different issues, dummy, he clearly has a lot more knowledge than you and and you just can't take it!

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Another fuckhead arrives. Lol. Get ready for more "knowledge" from the dumbass crowd. Check his grow pictures, sis.

Labworld= Dickhead. Another YouTube expert. Wait for it.

OneMoreRip said:

can you show me/us where different cannabis plants have different nutritional needs?

I also wouldn't add salts in my grow, from what I have read it can throw off balance in the growing medium. Just doesnt seem good to me. Pretty sure op already has nutes that he has used before with success, no need to add anything imo

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I'm not going to look for links. The other guy explained it well.
Thing is I don't go back and forth with stuff anymore here on RIU. I give my advice when I think it might be useful and anyone can take it or leave it. If someone I know and like wanted to debate my advice I always engage. If you notice none of the regulars read it and disagreed.
Right now from experience I see a Mg issue. I also have a good eye for PH issues and I'm not seeing that here. I also think when the OP looks at the roots at harvest he will see less root development in that pot.

Blackketch said:

View attachment 5033733

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There looks like a plastic pipe in this picture aimed at the rootmass with fly paper on the floor to catch bugs? is this cold air from outside?
If the root mass is being hit by cold air, the soil will take longer to dry out and this will affect the root mass, could cause root rot and if you water all the plants at the same time, you will be over watering this plant causing the leaves to turn yellow and it will slowly die.

the funny thing is i just got home and i noticed that the fan is not even plugged in. LOL

OneMoreRip said:

do you have anything scientific? I'm not assuming, I used to believe what you said before but the only scientist that studies cannabis, that I have come across, stated otherwise, from what l recall. and it ~makes sense to me as well. Not a big deal, just looking for something ~meaningful/scientific on the topic, been interested in it for a while

I was hoping to read up on it. thank you

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Anyone that has grown different strains at once can observe that some strains can tolerate higher level feeds than others. You dont need a scientific, peer reviewed research paper to observe that.

waterproof808 said:

Anyone that has grown different strains at once can observe that some strains can tolerate higher level feeds than others. You dont need a scientific, peer reviewed research paper to observe that.

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You're arguing with a guy that thinks 700ppm is 1.3 EC and uses a liquid ppm/EC meter to check his soil pH.