Strange red color showing up

7munkee · Dec 18, 2025

Hey guys. I am growing a reveged Girl Crush. This is a cross of Biscotti and Bad Girl. The upper part of the plant turned dark purple midway through flower the first time I flowered it.

The one on the left

THIS time, however, I am getting a red color on the tips and edges of the leaves in the middle of the plant and it started right after the flip to flower 18 days ago.

I don't think P lockout because no burnt or curling tips present, just the odd color. I would normally chalk this up to the Biscotti genetic, but this is a reveg and didnt show this last time I flowered it.

Anyone have a clue for me?

Ninjadogma · Dec 18, 2025

Howdy! Plants look like a nice canopy there! What I believe you've got going on is too much nutrients. Let me explain. Plants turn red from anthocyanins in the plant. Its triggers are cold weather, general plant stress and phosphorus uptake issues (could be either deficiency or lockout).

So we then have to look at visual clues on the plant. Phosphorus is a mobile nutrient. That means the plant will borrow nutrients from one spot and move them to another part of the plant where they're needed, for instance to focus on bud development.

Plants will take their mobile nutrients from the oldest leaves first, so if it's a deficiency you would be looking for those leaves to turn red or lose color toward the bottom of the plant.

As we can see from yours, it's further up on the top. This suggests a nutrient excess is causing a lockout, and they're not flowing to those middle leaves like they should. The usual culprit is what we call salt accumulation and what it means is there is just a high concentration of nutrients either throughout the soil, or sitting in pockets within the soil (aka channeling).

So your correction is going to be, next time you water, you want to give it a really good, very slow and very thorough watering so that the nutrients can get diluted down and you can break up any channeling going on. Presuming you're in 5 gallon pots, wait until about a quart of water has passed out the bottom, and it should take you about 30 minutes time doing pouring increments to get there. Any quicker and you're working too fast. So after about a quart flows out, collect some of it and test it with an EC pen, make a note of the number. Do another pour and collect it and take that reading. Compare the two and check if the second reading is higher or lower than the first. If it's higher, keep pouring until you see it fall. If it's lower but still a high number, pour until it comes down to a safe level.

So why did this happen to your plant, or rather how could it be prevented? The problem is you probably had lots of vegging nutrients in the soil and you started with the flowering nutes. When you're flipping, you want to reset the soil a little, give it a good heavy watering to push the excess vegging nutes out so you can load in your flowering nutes in and not having them compete for uptake.

The plant on the right is showing a similar problem but it probably doesn't have the genetics that triggers purple. So it has the exact same problematic fade going on but looks differently.

7munkee · Dec 18, 2025

Ninjadogma said:
Howdy! Plants look like a nice canopy there! What I believe you've got going on is too much nutrients. Let me explain. Plants turn red from anthocyanins in the plant. Its triggers are cold weather, general plant stress and phosphorus uptake issues (could be either deficiency or lockout).

So we then have to look at visual clues on the plant. Phosphorus is a mobile nutrient. That means the plant will borrow nutrients from one spot and move them to another part of the plant where they're needed, for instance to focus on bud development.

Plants will take their mobile nutrients from the oldest leaves first, so if it's a deficiency you would be looking for those leaves to turn red or lose color toward the bottom of the plant.

As we can see from yours, it's further up on the top. This suggests a nutrient excess is causing a lockout, and they're not flowing to those middle leaves like they should. The usual culprit is what we call salt accumulation and what it means is there is just a high concentration of nutrients either throughout the soil, or sitting in pockets within the soil (aka channeling).

So your correction is going to be, next time you water, you want to give it a really good, very slow and very thorough watering so that the nutrients can get diluted down and you can break up any channeling going on. Presuming you're in 5 gallon pots, wait until about a quart of water has passed out the bottom, and it should take you about 30 minutes time doing pouring increments to get there. Any quicker and you're working too fast. So after about a quart flows out, collect some of it and test it with an EC pen, make a note of the number. Do another pour and collect it and take that reading. Compare the two and check if the second reading is higher or lower than the first. If it's higher, keep pouring until you see it fall. If it's lower but still a high number, pour until it comes down to a safe level.

So why did this happen to your plant, or rather how could it be prevented? The problem is you probably had lots of vegging nutrients in the soil and you started with the flowering nutes. When you're flipping, you want to reset the soil a little, give it a good heavy watering to push the excess vegging nutes out so you can load in your flowering nutes in and not having them compete for uptake.

The plant on the right is showing a similar problem but it probably doesn't have the genetics that triggers purple. So it has the exact same problematic fade going on but looks differently.

This pots history is quite long. I have been using this same soil for a couple years. It's on its 8th? or 9th? cycle now. I am using a 15 gallon sip (12 gal soil and 3gal reservoir) running Clackamus Coot's mix and amended regularly. It is full worms and predator mites. I have most of these cycles documented somewhere on this site. This particular run is a reveg of a really good Biscotti and Bad Girl cross that I forgot to take cuttings from, hence the reveg. I spent a week away from it right after it reverted back to full blown veg cycle because I was sicker than hell and i missed out on at least one res fill. The soil wasn't dry because I have plastic on top. This encourages 'feeder' roots right where the food is. I give it fulvic acid plus Recharge each Saturday to help cycle nutrients.

P lockout was my first thought, but it's been like since a few days after I flipped the lights and there isnt any burnt or curling tips. I DID have a week were temps were a high of 70 in the day and as low as 59 at nights. It's in an upstairs closet in a unheated bedroom.

So your most probly right on it just being anthocyanins from the cold. The last time this plant was flowered it turned deep purple around week 4 of flower. This time it is actually RED. If I remember right, Biscotti tends to be a red/pinkish plant and this is half Biscotti genetics. Probly the cold brought it out earlier.

7munkee · Dec 18, 2025

7munkee said:
This pots history is quite long. I have been using this same soil for a couple years. It's on its 8th? or 9th? cycle now. I am using a 15 gallon sip (12 gal soil and 3gal reservoir) running Clackamus Coot's mix and amended regularly. It is full worms and predator mites. I have most of these cycles documented somewhere on this site. This particular run is a reveg of a really good Biscotti and Bad Girl cross that I forgot to take cuttings from, hence the reveg. I spent a week away from it right after it reverted back to full blown veg cycle because I was sicker than hell and i missed out on at least one res fill. The soil wasn't dry because I have plastic on top. This encourages 'feeder' roots right where the food is. I give it fulvic acid plus Recharge each Saturday to help cycle nutrients.

View attachment 2579417

P lockout was my first thought, but it's been like since a few days after I flipped the lights and there isnt any burnt or curling tips. I DID have a week were temps were a high of 70 in the day and as low as 59 at nights. It's in an upstairs closet in a unheated bedroom.

So your most probly right on it just being anthocyanins from the cold. The last time this plant was flowered it turned deep purple around week 4 of flower. This time it is actually RED. If I remember right, Biscotti tends to be a red/pinkish plant and this is half Biscotti genetics. Probly the cold brought it out earlier.

I should add I gave it a foliar of epsom and a bit of kelp meal/seabird guano/ Neemseed meal/gypsum/rockdust/Langbeinite/worm castings two weeks before flower. This is my typical flower topdress that I have used for 3 years.

Ninjadogma · Dec 19, 2025

7munkee said:
This pots history is quite long. I have been using this same soil for a couple years. It's on its 8th? or 9th? cycle now. I am using a 15 gallon sip (12 gal soil and 3gal reservoir) running Clackamus Coot's mix and amended regularly. It is full worms and predator mites. I have most of these cycles documented somewhere on this site. This particular run is a reveg of a really good Biscotti and Bad Girl cross that I forgot to take cuttings from, hence the reveg. I spent a week away from it right after it reverted back to full blown veg cycle because I was sicker than hell and i missed out on at least one res fill. The soil wasn't dry because I have plastic on top. This encourages 'feeder' roots right where the food is. I give it fulvic acid plus Recharge each Saturday to help cycle nutrients.

View attachment 2579417

P lockout was my first thought, but it's been like since a few days after I flipped the lights and there isnt any burnt or curling tips. I DID have a week were temps were a high of 70 in the day and as low as 59 at nights. It's in an upstairs closet in a unheated bedroom.

So your most probly right on it just being anthocyanins from the cold. The last time this plant was flowered it turned deep purple around week 4 of flower. This time it is actually RED. If I remember right, Biscotti tends to be a red/pinkish plant and this is half Biscotti genetics. Probly the cold brought it out earlier.

Well shit I could have saved myself a lot of typing

Yeah cold environment will look just like a salt problem, plant faces a similar issue with nutes not flowing good. Your fulvic in there should be helping. If you're not already using it, try seaweed. It helps too when the weather is chilly.

Edit: I see you mentioned kelp.

Ninjadogma · Dec 19, 2025

You know I'm just thinking, I don't see my plants start getting cold shock until overnight temps are dipping down to the high 40's and low 50's and while you might just have a fickle strain, it probably wouldn't hurt to stick a pen in some runoff and just double check it's not running too hot, because it does sound like you're running a lot of amendments in there overall. Leaf tips aren't indicating it though.

7munkee · Dec 19, 2025

This is a SIP. There is no runoff. Just plain tap water in the reservoir. Here is a pic of an empty one I found on the web:

The water lays an inch below the screen on the bottom. The water gets filled down the tube.

Ninjadogma · Dec 19, 2025

7munkee said:
This is a SIP. There is no runoff. Just plain tap water in the reservoir. Here is a pic of an empty one I found on the web:

View attachment 2579450
The water lays an inch below the screen on the bottom. The water gets filled down the tube.

Can you do me a favor? Can you grab a turkey blaster or one of those baby snot bulbs and collect some of that reservoir water, throw it in a cup, stick an EC pen in it and tell me what it reads? Make sure you wait half a day after adding water to collect.

You don't get runoff the traditional way but the way those things work, the water dripping in from the pot will Leach the salts into the reservoir, it's supposed to be why those things are so sweet, keeps the EC diluted with consistent moisture but not if it's overfed.

7munkee · Dec 19, 2025

Ninjadogma said:
Can you do me a favor? Can you grab a turkey blaster or one of those baby snot bulbs and collect some of that reservoir water, throw it in a cup, stick an EC pen in it and tell me what it reads? Make sure you wait half a day after adding water to collect.

You don't get runoff the traditional way but the way those things work, the water dripping in from the pot will Leach the salts into the reservoir, it's supposed to be why those things are so sweet, keeps the EC diluted with consistent moisture but not if it's overfed.

Sure. Tomorrow the res needs filled. I will take some in the evening. Only clean water goes in the reservoir and it doesn't make contact with the soil at all until it gets drawn up from the osmotic pressure. Roots do hang down through the screen though. There is always at least an inch of airspace because of the overflow, so the rootzone gets LOTS of oxygen. I think this is the secret to the fast growth in these things.

Ninjadogma · Dec 20, 2025

7munkee said:
Sure. Tomorrow the res needs filled. I will take some in the evening. Only clean water goes in the reservoir and it doesn't make contact with the soil at all until it gets drawn up from the osmotic pressure. Roots do hang down through the screen though. There is always at least an inch of airspace because of the overflow, so the rootzone gets LOTS of oxygen. I think this is the secret to the fast growth in these things.

Does it have a fill tube? You can draw a sample from there.

Ninjadogma · Dec 20, 2025

Ninjadogma said:
Does it have a fill tube? You can draw a sample from there.

So you know where I'm going with this, we just want to eliminate the possibility so we are collecting specific data, a specific way. I want to get a sample of that tank to compare against some fresh input, and that's going to confirm to us your SIP is working right and there's no drip down going on. The other sample we want to grab is a slurry, dig a little pocket from the top about 3 inches deep, take some spoonfuls and run a slurry on it and that will give us an inkling of where it's actually sitting, so we can breathe a sigh of relief that it really is just the cold. That's all.

7munkee · Dec 20, 2025

Ninjadogma said:
So you know where I'm going with this, we just want to eliminate the possibility so we are collecting specific data, a specific way. I want to get a sample of that tank to compare against some fresh input, and that's going to confirm to us your SIP is working right and there's no drip down going on. The other sample we want to grab is a slurry, dig a little pocket from the top about 3 inches deep, take some spoonfuls and run a slurry on it and that will give us an inkling of where it's actually sitting, so we can breathe a sigh of relief that it really is just the cold. That's all.

Yes I do. I didnt get to fill it until lights out tonight. I will let it set over night and check in the morning. It was 140ppm right after I filled it.. That would be like 0.30 EC I think.

JaBy · Dec 21, 2025

7munkee said:
Hey guys. I am growing a reveged Girl Crush. This is a cross of Biscotti and Bad Girl. The upper part of the plant turned dark purple midway through flower the first time I flowered it.

The one on the left
View attachment 2579272

THIS time, however, I am getting a red color on the tips and edges of the leaves in the middle of the plant and it started right after the flip to flower 18 days ago.

View attachment 2579273
I don't think P lockout because no burnt or curling tips present, just the odd color. I would normally chalk this up to the Biscotti genetic, but this is a reveg and didnt show this last time I flowered it.View attachment 2579277

Anyone have a clue for me?

i have been seeing red/purple in my plants. while i feel i have many issues afoot with my grow the thing i think is producing the red/purple is the temp. previous grows were getting a warmer temp for the entire day night cycle (generally 70 degrees) where this grow the temp has been at best higher 60's during light on and lower 60's/higher 50's at night.

Ninjadogma · Dec 21, 2025

JaBy said:
i have been seeing red/purple in my plants. while i feel i have many issues afoot with my grow the thing i think is producing the red/purple is the temp. previous grows were getting a warmer temp for the entire day night cycle (generally 70 degrees) where this grow the temp has been at best higher 60's during light on and lower 60's/higher 50's at night.

With cooler temps and to a certain degree, genetics, they swap out chlorophyll with anthocyanin. I don't know if anybody talks about it, but its an evolutionary advantage, with the darker color allowing the leaves to absorb more heat. Pretty cool hack on the plant's part, really. But the color temps aren't ideal, plant is throwing an environmental response which uses up energy. Treat your tent like an aquarium of tropical fish, they like it 78°.

Ninjadogma · Dec 21, 2025

7munkee said:
Yes I do. I didnt get to fill it until lights out tonight. I will let it set over night and check in the morning. It was 140ppm right after I filled it.. That would be like 0.30 EC I think.

Cool, so we have a benchmark reading of 0.28. When you get your second reading and separate slurry done, let's circle back.

7munkee · Dec 21, 2025

No change really. 160ppm. I am not going to dig into my soil for a slurry test.. I spent almost 3 years developing the texture. I don't even remove the old stalks because they are just more worm food.

Strange red color showing up

Strange red color showing up

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