Can someone tell me the TRUE reason for hard purple stems?

  • Thread starter geralds
  • Start date
  • Tagged users None
1diesel1

1diesel1

Staff
Supporter
11,244
438
BigBlonde

BigBlonde

1,379
263
I have never been able to find a solid cause for the purple stems. Here's a weird clue... One summer I grew identical clones indoor and outdoor. The indoor ones had purple stems, the outdoor ones had perfectly green stems. Used the same nutrients for both. Outdoor was in the earth, not pots.

Also, I have moved indoor plants with purple stems outdoor and plated in the ground, all the new growth had green stems.
I had the same thing happen with tomato plants. They were purple under LED lights. I took some cuttings and put them in soil outside and the purple turned green.
 
BigBlonde

BigBlonde

1,379
263
I've seen purple frequently. So, does that mean I have a light problem or some other form of stress? Or is the answer "It depends."

I recently moved some plants from one tent to another. They had purple stems and slow growth in the first tent. Now, int the second tent, the new growth is green and the plants are growing better. The second tent must have a better environment.
 
Last edited:
Choppr

Choppr

519
143
Its from All the Purple Hybridizing over the last 15 years, the purple (antho) is in the DNA of all hybrids now - some are purple from the start. Some are effected more by cold overnights, I also think LED lighting has some affect on this, I didnt notice as much when we ran HID's back in the day...My Plants that are Purple Stemmed turn out nicely, and I never even think twice about it -
 
Homesteader

Homesteader

3,477
263
All LEDs you are seeing are really Red and Blue with a varying level of yellow phosphorous coat over top. The blue and red are what feed the anthocyanin pigment and also why you see this in LED grown herb more than HPS. Add more blue and red to your light recipe, get more purple but ONLY if the anthocyanin is in the genetics of the strain.
 
A

Alwispy

124
63
I've seen purple frequently. So, does that mean I have a light problem or some other form of stress? Or is the answer "It depends."

I recently moved some plants from one tent to another. They had purple stems and slow growth in the first tent. Now, int the second tent, the new growth is green and the plants are growing better. The second tent must have a better environment.
Is there any differences between the two tents as far as lighting goes ?
 
BigBlonde

BigBlonde

1,379
263
Is there any differences between the two tents as far as lighting goes ?
Yes. But there are other differences. The first tent is a first use 2x2 with an XS1000 light hung about 24 inches above the soil level. The second tent is a 2x4 with an SX2000 light. The new 2x2 also had problems with heat and humidity, so it's not a good comparison. The plants were also up potted to 1-gallon plastic pots.

My plan was to start plants in a small tent while plants in the big tent were flowering. I soon discovered that the environment in the smaller tent was harder to regulate. So, now I'm rethinking my initial plan.

I don't want to hijack this thread. I might start a thread, if I think I need it.
 
BigBlonde

BigBlonde

1,379
263
All LEDs you are seeing are really Red and Blue with a varying level of yellow phosphorous coat over top. The blue and red are what feed the anthocyanin pigment and also why you see this in LED grown herb more than HPS. Add more blue and red to your light recipe, get more purple but ONLY if the anthocyanin is in the genetics of the strain.
I have been suspecting that LED lights have issues. I've been particularly concerned about light stress or burn. I put wattage meters on my lights so I can control the dimmer (i.e., the power) with greater accuracy.
 
Homesteader

Homesteader

3,477
263
Light stress under LED is probably due actually a plateau of CO2 or less likely other parameters like nutrients or water. My plants get enormous amount of light compared to some of the lights people use and the most that happens when CO2 is peaked is I will get albino bleached tips like in the picture. IMO a dimmer is only needed for the first few weeks.
 
BigBlonde

BigBlonde

1,379
263
Light stress under LED is probably due actually a plateau of CO2 or less likely other parameters like nutrients or water. My plants get enormous amount of light compared to some of the lights people use and the most that happens when CO2 is peaked is I will get albino bleached tips like in the picture. IMO a dimmer is only needed for the first few weeks.
Indeed, there's nothing better than healthy plants. Perhaps if I ever become good at growing, I'll be able to run my lights at a higher power level. For now, though, turning the power down accommodates my poor growing ability.
 
N1ghtL1ght

N1ghtL1ght

Staff
Supporter
670
143
I always say it, if you want to understand Algriculture you have to go ask someone who has a Degree in Algriculture. Asking people who have no engineering experience in that field will get you nothing but people guessing and giving you 50 different answers, who do you believe? Exactly, u don't know who is correct and who is false. First off, It's never genetics and if anyone ever say that again get far away from them. Purple Hard Stems is never a genetics trait. Go outside where it grows naturally and find one, it doesn't exist.

Now, purple hard stems is a result of a few things happening simultaneously. It's a result of stress from TO MUCH LIGHT, to high of ppdf or umols/m2. The plant can't photosynthesis all that light. Lets go back to its roots and let's evaluate this the correct way directly from a Master Engineer. A cannabis plant uses light, water and co2 then converts it into sugar and oxygen as waste. It stores the sugar for 12 hours then uses it when lights out. It's like carbohydrates for plants. Cannabis plants are phototrophic, meaning it can create its own organic nutrition unlike humans, we get ours from food, our bodies can't create calories and protein on its own. LED lights are very intense unlike natural sunlight at 1500 ppfd the plant does not struggle like 1500 ppfd of light indoor. Natural sunlight and the environment is much absorbing outdoors than indoors and there is no reflection on sunlight and the sun rotates, it's not fixed. When light is fixed it beams one direction 18 hours, it's to much. Plus the added reflection from the mylar tents, its to much. Outside the light goes back to the atmosphere, indoors the light goes left right back to the plant, its to much. The plant has no choice but to photosynthesis all that light, it runs out of Magnesium very fast. Magnesium is the center molecule that builds cloroplast in chlorophyll,
magnesium is the center atom. That's why it's always the first to run out, purple is mag deficiency. Adding Magnesium will not fix it if it's depleting from to much light. It can't build cloroplast fast enough to keep up with Chlorophyll production as mag is deplete. This causes the plant to heat stroke itself and the stems turn hard as a slow growth factor. It's protecting itself. To stop this get a ppfd meter and stay under 375 ppfd in Veg and under 700 in flower without Co2 supplement.
Sir, I'm sorry but alot of what you stated is factually incorrect. Let me just begin that in that regard your personal status doesn't matter much it's actually a logical fallacy. @Moe.Red has already previously explained that to you.

Now to your points:
- Outside most plants get a higher DLI than indoors, if the summer day is cloudless. And, unlike indoors, they do get this at almost every leaf that isn't sitting in the shade. Actually our sun is a tad too strong during midday for best photosynthesis so plants developed all kinds of different strategies to cope with that. One such strategy is to *reduce* the number of chloroplasts per leaf area, and this has been shown by studies for more than half a century. McCree has it. This has the additional effect of increased leaf-transmittance.
- Outside the direct sunlight gets scattered by the molecules of our atmosphere to form the diffuse skylight. This light still has quite the power to drive photosynthesis - just stand in the back of your house in a shadow and aim for the blue sky with a lux or quantummmeter, you'll see this confirmed. There have been studies and it's about roughly 20-30% of all plants carbon that is derived from this diffuse light.
- Purple isn't Mg def (Mg def causes leaf stripe chlorosis) but it's more relatd to P-def or many forms of physiological toxicities, even pH imbalances which cause some of the internal biosynthetic processes to be stalled which causes an anthocyanin (relative) overproduction of processes which are NOT limited (the plant internal synthesis of specific biomolecules do not always need access to all essentials fully, quite the opposite).

BTW you may wanna research into S. Chandras work into photosynthesis rate of his Mexican Sativa - it will still show an increase in PS rate above 2000umol/m^2/s even at atmospherical CO2.

It is true that the center Mg atom can be displaced by a highlight scenario but this is something which can be repaired in the presence of white light on the fly. If not, if something goes south, this can rather lead to bleaching - of the leaf, not the stalk or petiole.
 
Dirtbag

Dirtbag

Supporter
9,158
313
Nature of the beast, weed out as quickly as it is found. This one I suspect is, I’ve noticed it responds to its own posts as a question from a member.
So not only do you have overconfident ignoramuses dropping knowledge turds everywhere, now you have to watch out for AI bots regurgitating and repeating their nonsense?
What a time to be alive...
 
Last edited:
RootsRuler

RootsRuler

2,389
263
Not sure where they got that ag degree, but I think they are correct to ask for their money back.
That dog don’t hunt!
Must've got his degree from the Al Bundy School of Agriculture hence the degree in "Algriculture"

Old MacBundy
 
Last edited:
RootsRuler

RootsRuler

2,389
263
Sir, I'm sorry but alot of what you stated is factually incorrect. Let me just begin that in that regard your personal status doesn't matter much it's actually a logical fallacy. @Moe.Red has already previously explained that to you.

Now to your points:
- Outside most plants get a higher DLI than indoors, if the summer day is cloudless. And, unlike indoors, they do get this at almost every leaf that isn't sitting in the shade. Actually our sun is a tad too strong during midday for best photosynthesis so plants developed all kinds of different strategies to cope with that. One such strategy is to *reduce* the number of chloroplasts per leaf area, and this has been shown by studies for more than half a century. McCree has it. This has the additional effect of increased leaf-transmittance.
- Outside the direct sunlight gets scattered by the molecules of our atmosphere to form the diffuse skylight. This light still has quite the power to drive photosynthesis - just stand in the back of your house in a shadow and aim for the blue sky with a lux or quantummmeter, you'll see this confirmed. There have been studies and it's about roughly 20-30% of all plants carbon that is derived from this diffuse light.
- Purple isn't Mg def (Mg def causes leaf stripe chlorosis) but it's more relatd to P-def or many forms of physiological toxicities, even pH imbalances which cause some of the internal biosynthetic processes to be stalled which causes an anthocyanin (relative) overproduction of processes which are NOT limited (the plant internal synthesis of specific biomolecules do not always need access to all essentials fully, quite the opposite).

BTW you may wanna research into S. Chandras work into photosynthesis rate of his Mexican Sativa - it will still show an increase in PS rate above 2000umol/m^2/s even at atmospherical CO2.

It is true that the center Mg atom can be displaced by a highlight scenario but this is something which can be repaired in the presence of white light on the fly. If not, if something goes south, this can rather lead to bleaching - of the leaf, not the stalk or petiole.
Thank you for clearing that up.
 
1diesel1

1diesel1

Staff
Supporter
11,244
438
Straight from the horses mouth;


Red or purple stems caused by genetics or light
Purple strains with very dark foliage, for example, often develop purple stems too, especially if you grow them in slightly cooler temperatures. As long as your plants look otherwise healthy, there's usually no reason to worry.
 
Novaracer69

Novaracer69

533
143
I know I grow indoors and out I have seen this multiple times and I am 99% sure it's the LED lights. It has something to do with it because I do same thing inside and out. Same soil mix same nutrition. Now I have been successful using gypsum when I topdress. But even then it's not 100percent perfect.
 
Dirtbag

Dirtbag

Supporter
9,158
313
I know I grow indoors and out I have seen this multiple times and I am 99% sure it's the LED lights. It has something to do with it because I do same thing inside and out. Same soil mix same nutrition. Now I have been successful using gypsum when I topdress. But even then it's not 100percent perfect.
It's not just LED, I've had stems go purple on me indoors under HID before also, when outdoors they don't.
It's a complicated difference that i dont really understand. Outdoors, plants are in their natural environment, they generally have MUCH higher brix in the sap when tested, they're recieving a true full spectrum of light which doesnt suffer from the inverse square law so it tends to supply the entire plant down to the base with adequate light penetration, they have constant gas exchange, and a lot more going on.

I dont fully comprehend exactly what the important differences really are when you bring plants inside if I'm being honest, but I do know that given an indoor grow and an outdoor grow below the 47th parallel, the outdoor grow will always be a little easier, or more foolproof to manage.
 
Novaracer69

Novaracer69

533
143
It's not just LED, I've had stems go purple on me indoors under HID before also, when outdoors they don't.
It's a complicated difference that i dont really understand. Outdoors, plants are in their natural environment, they generally have MUCH higher brix in the sap when tested, they're recieving a true full spectrum of light which doesnt suffer from the inverse square law so it tends to supply the entire plant down to the base with adequate light penetration, they have constant gas exchange, and a lot more going on.

I dont fully comprehend exactly what the important differences really are when you bring plants inside if I'm being honest, but I do know that given an indoor grow and an outdoor grow below the 47th parallel, the outdoor grow will always be a little easier, or more foolproof to manage.
Your right there's just something about the sun 🌞 we just can't replicate yet😉
 
Top Bottom