Certain plants more susceptible to light stress?

[ntg908]

I have a couple plants im growing indoors with a Mars Hydro TSW2000. I have gone through a couple grows with no problems as far light and heat stress at the distances i have been at. Now i am growing 2 GDP clones at the same distance im usually at ( week 4 of veg at about 24 inches full blast) and have the noticable curling leaves and rusting spots and yellowing on top growth. Ive gone through everything as far as deficiencies that could cause the rust spots and yellowing, but the curling leaves are a tell tell of light stress i believe. Do different plants just sometimes cant take as much light? Its weird because they are clones and 1 of them is curling hard, the other not so much, same distance from light. Any help is apreciated

 

[Richard Drysift]

I am willing to bet it has more to do with what you are growing them in than light stress. I have seen “bleaching” from cheapo led panels where the leaves literally lose all color and turn almost white but leaf curl is typically related to temperature or RH. If yellowing is occurring from top-most recent growth the root cause of all these issues could be related to ph (absorbtion). Pics might help...

 

[piratebug]

Any pictures?

 

[ntg908]

I am willing to bet it has more to do with what you are growing them in than light stress. I have seen “bleaching” from cheapo led panels where the leaves literally lose all color and turn almost white but leaf curl is typically related to temperature or RH. If yellowing is occurring from top-most recent growth the root cause of all these issues could be related to ph (absorbtion). Pics might help...

Any pictures?

Bleaching is a normal thing that happens any time your buds are too close to the light. Not because of the type of LED, maybe if it gives off more heat? but light does it not heat. i follow VPD to the T so RH and temp are not the issues at all. i grow in DWC also and have ph regulators and check twice a day so that cant be it either. Here are some pics. You can see how far my light is from the canopy, i just moved it to 24 inches and the rust spots seemed to slow down, but still continue, and the leaf curling is new. Giant good pretty white root balls so no root nutrient uptake problem either. This is whats leading me to believe certain plants (even between clones) can maybe be WAY more sensative to light?

 

[Richard Drysift]

Yep, bleaching can occur and I’ve seen it but that looks like nutrient burn. Back off ppms

 

[ntg908]

Yep, bleaching can occur and I’ve seen it but that looks like nutrient burn. Back off ppms

Nutrient burn wouldnt only show up on new growth would it? plus it usually goes from the tip on downward? not in patches. Idk thats just what books tell me im not being ugly

 

[SnidleyBluntash]

Yes have you changed mediums? I have had plants in dwc and also in dirt and the dwc can handle the lights more.

 

[ntg908]

Yes have you changed mediums? I have had plants in dwc and also in dirt and the dwc can handle the lights more.

I havnt, the space im in DWC works much better for me and its all ive ever known. Every other plant ive grown has done fine. If they are more sensative to light stress do you think switching from 24 on to 18/6 will ease them out a bit and give them a little break? Thats the only thing i havnt tried because i like that rapid growth lol.

 

[Richard Drysift]

Nutrient burn wouldnt only show up on new growth would it? plus it usually goes from the tip on downward? not in patches. Idk thats just what books tell me im not being ugly

Sure, in DWC? Things happen fast in hydro grows...even just a little too much nutrient can burn. Are you mixing w/ measuring spoon or do you use TPS meter? Mixing by ppm is much more accurate. While I don’t think certain strains are more/less sensitive to electric lighting than others they definitely can be to synthetic nutes. I’ve given my plants some of the most intense lighting available and never seen a single detriment over decades of growing pot. Nutes are a very different story.
Giving the plants a break even for a few hours a day is always a good idea though I know there are autos that run 24/0. If they are autos try to go 20/4. Not that it would be the cause of this but heat could play a factor here. Also get a good idea what is in the water you use. Tap should be fine but if you have hard water or let’s say water from a well that salt is added to that could be a possible cause of necrosis like this.

 

[ntg908]

Sure, in DWC? Things happen fast in hydro grows...even just a little too much nutrient can burn. Are you mixing w/ measuring spoon or do you use TPS meter? Mixing by ppm is much more accurate. While I don’t think certain strains are more/less sensitive to electric lighting than others they definitely can be to synthetic nutes. I’ve given my plants some of the most intense lighting available and never seen a single detriment over decades of growing pot. Nutes are a very different story.
Giving the plants a break even for a few hours a day is always a good idea though I know there are autos that run 24/0. If they are autos try to go 20/4. Not that it would be the cause of this but heat could play a factor here. Also get a good idea what is in the water you use. Tap should be fine but if you have hard water or let’s say water from a well that salt is added to that could be a possible cause of necrosis like this.

Im using TDS with the base 3 GH FloraMicro FloraGro and FloraBloom and ofc calmag with RO water. Ive seen nutrient burn plenty of times just never like this. Usually starts at the tip and burns the WHOLE leaf all the way down, not in like spots. Ive ran my last 2 runs at this stage in their live around 900ppms with no problem. These are around 850. I thought the rusting was severe calcium deficiency since its RO but i added more and foliar sprayed and nothing. Now the leaves are curling up and i just dont know. Like i said i follow a VPD chart to the T so its hard to believe temp or humidity is the issue. room around 72-73 during day with a 1 degree drift at night, RH at around 52 which makes a perfect 1 on the VPD chart. Should i cut back on 850ppms? I dont wanna end up with some baby nugs this was a 25 dollar seed these clones came from lmfao

 

[loco41]

Im using TDS with the base 3 GH FloraMicro FloraGro and FloraBloom and ofc calmag with RO water. Ive seen nutrient burn plenty of times just never like this. Usually starts at the tip and burns the WHOLE leaf all the way down, not in like spots. Ive ran my last 2 runs at this stage in their live around 900ppms with no problem. These are around 850. I thought the rusting was severe calcium deficiency since its RO but i added more and foliar sprayed and nothing. Now the leaves are curling up and i just dont know. Like i said i follow a VPD chart to the T so its hard to believe temp or humidity is the issue. room around 72-73 during day with a 1 degree drift at night, RH at around 52 which makes a perfect 1 on the VPD chart. Should i cut back on 850ppms? I dont wanna end up with some baby nugs this was a 25 dollar seed these clones came from lmfao

No expert, but those temps seem a bit low for leds. I dont follow the vpd chart at all and only use a clip and extraction fan to control environment, but I think my plants seem happiest around 80-83 for temps.

Maybe search through the led threads for some good info on environmental ranges more specific to leds.

 

[ntg908]

No expert, but those temps seem a bit low for leds. I dont follow the vpd chart at all and only use a clip and extraction fan to control environment, but I think my plants seem happiest around 80-83 for temps.

Maybe search through the led threads for some good info on environmental ranges more specific to leds.

Why do LED's have anything to do with that? They give off less heat. And you should follow VPD because it determines how much water your plant can drink (with nutes) because it can transpire effectively. LEDs shouldnt have anything to do except them giving off little heat which you dont have to fight with, which you do with something like HPS. The lights you have dont determine what temp you room needs to be, the plant does. And i agree some plant thrive more in different conditions, but according to VPD you have to change the RH accordingly. Not being ugly btw just asking out of curiosity what makes you say that

 

[Learning1234]

Your temps are too low for LED. LEDs aren’t putting off the same light as HPS and whatnot, which raise the leaf temp about 3* above ambient room temps. LEDs don’t. Raise your room temps to 80* and get your RH in the 60%-70% range with good air movement in the room. Your plants will be a lot happier and grow a heck of a lot faster.

 

[ntg908]

Your temps are too low for LED. LEDs aren’t putting off the same light as HPS and whatnot, which raise the leaf temp about 3* above ambient room temps. LEDs don’t. Raise your room temps to 80* and get your RH in the 60%-70% range with good air movement in the room. Your plants will be a lot happier and grow a heck of a lot faster.

There is 0% chance i can raise my room temp to 80 and have a cool reservoir without a chiller which i dont have. I will root rot instantly. And i have a laser temp gun leaf temp ia bout 2 UNDER room temp, which is the temp you go off of for VPD

 

[loco41]

Why do LED's have anything to do with that? They give off less heat. And you should follow VPD because it determines how much water your plant can drink (with nutes) because it can transpire effectively. LEDs shouldnt have anything to do except them giving off little heat which you dont have to fight with, which you do with something like HPS. The lights you have dont determine what temp you room needs to be, the plant does. And i agree some plant thrive more in different conditions, but according to VPD you have to change the RH accordingly. Not being ugly btw just asking out of curiosity what makes you say that

Again no expert, but I believe it has to do with the lack of ir in the led spectrum that causes to leaf surface temp to be lower under leds than hids. So raising ambient temps in the grow area helps to get the plants in that ideal range for transpiration.

I'd suggest reading through or posting this issue over in the led sub forum and some far more knowledgeable people than myself can help assist. Not trying to say your wrong, just things i have stumbled upon in my readings. Wish you nothing but success moving forward though.

 

[ntg908]

Again no expert, but I believe it has to do with the lack of ir in the led spectrum that causes to leaf surface temp to be lower under leds than hids. So raising ambient temps in the grow area helps to get the plants in that ideal range for transpiration.

I'd suggest reading through or posting this issue over in the led sub forum and some far more knowledgeable people than myself can help assist. Not trying to say your wrong, just things i have stumbled upon in my readings. Wish you nothing but success moving forward though.

I see, most of what i say is from Oaksterdam textbooks and being around commercial growers so i kinda just repeat that. As far as i understood, your plant genetics determine what temp they wanna be at, and you have to adjust according to what light you have AND what the plant desires. Also i blast IR and UV ontop of full spectrum. but all this goes back to my initial problem aswell, if i have light and heat stress causing my curling leaves, HOW could my temp be low? Will be going to that forum

 

[loco41]

I see, most of what i say is from Oaksterdam textbooks and being around commercial growers so i kinda just repeat that. As far as i understood, your plant genetics determine what temp they wanna be at, and you have to adjust according to what light you have AND what the plant desires. Also i blast IR and UV ontop of full spectrum. but all this goes back to my initial problem aswell, if i have light and heat stress causing my curling leaves, HOW could my temp be low? Will be going to that forum

I feel like I'm a professional at regurgitating things I've read while having little to no experience, so I apologize if what I've said is off base.

Do you supplement ir and uv or is it built into your main light?

 

[ntg908]

I feel like I'm a professional at regurgitating things I've read while having little to no experience, so I apologize if what I've said is off base.

Do you supplement ir and uv or is it built into your main light?

The Mars TSW2000 has IR build in, i suppliment UV

 

[SnidleyBluntash]

The temperature allows the leaves to do their thing. If the leaf tempurature isn’t high enough the leaf will be recieving all the light, but not be able to use it, and it will have bad effects on it.

Different plants will have different everything about them. Take a clone of this plant just for safe keeping!

And, yes you could try to go to less hours. If you are really blasting them with light you might be over doing the DLI daily light ‘interval?’, which is the amount of light intensity a plant needs per day. Look it up, maybe that’s the issue.

You have purple stems, maybe ur temp is too low.... not enough phosphorus..? Is it wind burn from a fan?

 

[ntg908]

The temperature allows the leaves to do their thing. If the leaf tempurature isn’t high enough the leaf will be recieving all the light, but not be able to use it, and it will have bad effects on it.

Different plants will have different everything about them. Take a clone of this plant just for safe keeping!

And, yes you could try to go to less hours. If you are really blasting them with light you might be over doing the DLI daily light ‘interval?’, which is the amount of light intensity a plant needs per day. Look it up, maybe that’s the issue.

You have purple stems, maybe ur temp is too low.... not enough phosphorus..? Is it wind burn from a fan?

The puple stem is from root issues earlier, the entire stem was purple and as soon as i fixed my root problems they started turning green again....but not all the way, some stayed i think its permanent. I dont think phosphorus because no leafs turned purple, i think it was stress because of the roots that turned them purple. and by DLI you mean ppfd? i have a PAR meter that i could use. Its only a 300 watt light but maybe. but thats why i thought maybe moving it further and dimming it