Is this light bleaching?

2 plants, 3 gal fab pots
Temp 75, rh 40
2x Geciliaoran G1000 100w LED(301H)

So I looked up photos, and this does look sort of like bleaching. But just want confirmation. I'm in week 2 flower and still have to keep my lights@ 50% and 22-24inches away. Turned up to 60% for two days and...

Taco'ing

Bleaching? It's whitish on the ridges

Definitely not light bleaching.
Their PAR Map says at 24" with the light on full - 100 watts, reads 512 ùmols.
You have your lights set at 50 - 60% at 22" - 24" away that's low light levels.
You could raise your temperature up a bit if possible too.
At around 12" - 15" would be optimum for flowering with those lights.

That couple be the early stages of "interveinal chlorosis" which is a symptom of magesium deficiency.

On the other hand, it looks an awful lot like my plants do and it's just the "helicopter plant daddy" mode that I get into. It's very common for new growth to have that color and your plants look great.

Tacoing - Moflow did the math; to me, the leaves look great.

Bleaching - don't see any evidence and the only thing I know about bleaching from a Bugbee video. In that discussion, the bleaching is only seen well into flower and buds are white. Bugbee has narrowed it down to high light levels (800µmol, let's say) and was in lights that were >=60% red (660nm) and those conditions are not common in the personal/home grower market.

I appreciate it growmies! I'll give it a shot bumping it back to 60-70%. As for the mag looking issues, I did have mag/cal deficiency about 3-4 weeks ago. That's since been remedied. Got soil pH around 6.5, FF big bloom and Tiger bloom both have mag.

I'll give her some more light. Hopefully that really brings on a stretch! As for temps, well I heard 70-76 is ideal on Mr.Grow-it interviewing with some scientist. Also my temps were hitting 81-83 normally but I finally realized my tent has vent flaps 4" from the base so much more air in! Dropped temp immediately to stable 75.

Edit: is tacoing more of sides curling up rather than both sides "V" from a blade's center vein?

Well the lights be at 70% and temp 77|rh 42%. See how they do

81-83F is about ideal with LED lights. Unlike HID lights, they don't raise leaf temps above air temp with infrared.

bignugs68 said:

I appreciate it growmies! I'll give it a shot bumping it back to 60-70%. As for the mag looking issues, I did have mag/cal deficiency about 3-4 weeks ago. That's since been remedied. Got soil pH around 6.5, FF big bloom and Tiger bloom both have mag.

I'll give her some more light. Hopefully that really brings on a stretch! As for temps, well I heard 70-76 is ideal on Mr.Grow-it interviewing with some scientist. Also my temps were hitting 81-83 normally but I finally realized my tent has vent flaps 4" from the base so much more air in! Dropped temp immediately to stable 75.

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"some scientist" - that was probably an interview with Dr Bruce Bugbee, arguably the biggest wheel going in the area of plant biology in the US. Check out his YouTube videos — they're excellent.

I just finished watching and taking notes on this video
The speaker is a PhD candidate who works with Bugbee and the information in the video is superb. Growers will benefit from the content, especially the part where he talks about light levels at 25:40. From my notes:

"25:48
Light quantity
Most companies measure a single leaf - 6 cm2 but that does not cover the canopy

What's remarkable about cannabis is that canopy photosynthetic rate continues to increase all the way up to full sunlight.

Peak sunlight is about 2k, this line is still going up.

As a grower, we don't care about how many mols of CO2 are being fixed every second. We don't care about photons falling every second. We want to know how much (rain) fell over the course of a day.
Rather than looking at PPFD, we can look at DLI.

P continues to go up - does that translate to yield.

10, 30, 50, and 70 mols so the highest treatment was about 20% higher than full summer sunlight and the yield went up in a linear fashion. 1% more light, 1% more yield.

James Nielson - went to 100mols and yield keeps going up.

Wetmoreland was ambient CO2 - Nielson was elevated CO2"

"P" is an abbreviation for photosynthesis.

There's a lot more in there, esp. the data on the role of phosphorus and, implicitly, the usefulness of bloom boosters.

bignugs68 said:

Edit: is tacoing more of sides curling up rather than both sides "V" from a blade's center vein?

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Yes, you hit it on the head. Another term is "canoeing".

Another photo avoidance mechanism is for the leaf to rotate around the axis of the petiole.

I've hit both of those and the affected leaves will return to their normal position and shape pretty quickly. It's been 30-60 minutes but I did have a bent cola that never straightened back out.

Awesome timing brother/sister? And it was either Bugbee or "Matt from Debacco University"....Found it, Matt has good info as well, but this one is Bugbee. Here's the timestamp link - 34:00, that whole video is awesome though. My stoned brain remembered the data as 70-76 , but Bugbee actually said "low 70's with ambient CO2...with CO2 fed - into the 80's"; Just got home and they've had 10.5hrs at 70%. Idk growmies, looks like my girls had a rough day.?.?

This morning



Just now 10ish hrs later



I did turn down to 60% upon seeing them depressed lol.

Course, second look as I dribble watered the soil surfaces - top inch dries so fast and there's gotta be roots there too; the fan leaves def grew and it looks like they're darker than this morning. Here a better sky pic to match this mornings.

Morning first



So they grew, darkened, but look like me after 15hr shift in oil/gas field digging in dirt on a 90 degree day. What do yuns think?? And super appreciate the help and advice mates n ladies!

EDIT: I also removed the huge fan leaves under the canopy that were under the "topped" main colas as I read somewhere that new leaves will do more for the plant than old ones that have reached maturity and are under the canopy.

bignugs68 said:

Course, second look as I dribble watered the soil surfaces - top inch dries so fast and there's gotta be roots there too; the fan leaves def grew and it looks like they're darker than this morning. Here a better sky pic to match this mornings.

So they grew, darkened, but look like me after 15hr shift in oil/gas field digging in dirt on a 90 degree day. What do yuns think?? And super appreciate the help and advice mates n ladies!

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"yuns" - that's a Pittsburgh-area expression but it's not 90 in Pittsburgh.

Re. the Mr. Growit video - thanks for the link. The 34:00 mark is the start but he gets to the heart of the matter at 35:50 - bud temp. This video is from 12/21 vs the Westmoreland video which was 11/23 (12/23?) so I'm thinking that Bugbee and Westmoreland were working back then because that's topic is/is part of Westmoreland's PhD thesis, which requires years at least a couple of years of work. Another go Bugbee's students has the last name of "Zheng". You'll see that name attached to cannabis research.

deBacco uses a lot of Bugbee material and reads.every.slide. He's good for the "Cliff Notes" in contrast to Bugbee who provides the "why" and "how"; deBacco does the "what". deBacco goes into a lot of topics, far more than just light. His video about judging the state of trichomes by their color is really helpful.

From the "Light Values" page in my grow journal from my first grow in 2022. I had been growing a little over a hear at the time and had read/watched a lot of info from Bugbee and deBacco but I wasn't on the "high light" train yet. After watching one of his videos for the nTh time that I finally pulled the trigger on "lotsa light".

And, yeh, thrips. Hate the little bastards…



Re. your grow — I grow I hydro and the only thing I know about soil is that how you water is really important. I can tell you've been doing this a while, so no offense meant, but could it be something that basic?

Delps8 said:

"yuns" - that's a Pittsburgh-area expression but it's not 90 in Pittsburgh.

Re. the Mr. Growit video - thanks for the link. The 34:00 mark is the start but he gets to the heart of the matter at 35:50 - bud temp. This video is from 12/21 vs the Westmoreland video which was 11/23 (12/23?) so I'm thinking that Bugbee and Westmoreland were working back then because that's topic is/is part of Westmoreland's PhD thesis, which requires years at least a couple of years of work. Another go Bugbee's students has the last name of "Zheng". You'll see that name attached to cannabis research.

deBacco uses a lot of Bugbee material and reads.every.slide. He's good for the "Cliff Notes" in contrast to Bugbee who provides the "why" and "how"; deBacco does the "what". deBacco goes into a lot of topics, far more than just light. His video about judging the state of trichomes by their color is really helpful.

From the "Light Values" page in my grow journal from my first grow in 2022. I had been growing a little over a hear at the time and had read/watched a lot of info from Bugbee and deBacco but I wasn't on the "high light" train yet. After watching one of his videos for the nTh time that I finally pulled the trigger on "lotsa light".

And, yeh, thrips. Hate the little bastards…
View attachment 5382097


Re. your grow — I grow I hydro and the only thing I know about soil is that how you water is really important. I can tell you've been doing this a while, so no offense meant, but could it be something that basic?

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Very astute of you on the yuns, it's popular in WV hollers too haha.

Nice!!! Sooo much good info, I need to build a playlist for long trips on the road.

And Thank you for thinking I've been at it a while! Honestly just read a lot and then watch vids on aspects I need over explained lol. This is only my 2nd grow/first indoors. My first grow was 4-5 years ago outdoors; this grow is same strain/bag seeds. Had a kid, life etc. but saved the rest the seeds in cellophane, in marb box, in a metal tin till I could try again - some dreams do come true haha.

Main Question Answer: So based on the growth and better coloring, increase was good. But the leaves are almost lifeless. Most say water 1/3 your pot, I've been only giving them 1/6(half gal) each every 2-3 days. I go slow and get mild runnoff. Maybe at 70% light intensity I will be watering at the standard or..1/2 gal every 1-2 days?..? Sorry haha thinking and asking at the same time.

bignugs68 said:

Just got home and they've had 10.5hrs at 70%. Idk growmies, looks like my girls had a rough day.?.?

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looks like the plants are receiving too much light for the environmental conditions, likely a VPD/transpiration issue. I would raise your ambient temps into the mid 80s and let your soil dry out just a hair before your next irrigation cycle. I would also aim for 50+% for your humidity. Look up VPD Chart if you aren’t familiar. We are more concerned with leaf temps than ambient. If your stems are starting to stripe or turn purple, vpd being out of range is a likely culprit.

cdgmoney250 said:

looks like the plants are receiving too much light for the environmental conditions, likely a VPD/transpiration issue. I would raise your ambient temps into the mid 80s and let your would dry out just a hair before your next irrigation cycle. I would also aim for 50+% for your humidity. Look up VPD Chart if you aren’t familiar. We are more concerned with leaf temps than ambient. Of your stems are starting to stripe Or turn purple, vpd being out of range is a likely culprit

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What signs are you seeing that indicate that the plant is receiving excess light?

I fully understand that "high light" is only achieved when a grow is in tip top shape and that's not the case.

The canopy is very flat and I don't see anything that indicates that there's excess light. Overall, very few of the leaves are even horizontal and I don't see anything that resembles photo avoidance.

I do see leaves that have look to be low on fertlizer, based on their light color, and some of the leaves are turning down which is, I believe, a symptom of overwatering or improper watering.

When light is in excess, it affects the top most parts of the canopy the most, gradually diminishing as you move from the light source. I don't see any change in the foliage. It's all light green and drooping in some parts.

The problem with the "turn the light down because it might be excess light" is that we're dealing with modest amount of light to begin with and, since light is the only way the plants can create "food", lowering light that are not in excess will reduce the plants' ability to generate energy which may exacerbate the problem.

VPD being out of range causes purple (red) - that's a new one. Nothing I've read on VPD deals with changing color of stems. VPD being too high tends to cause nutrient imbalances, typically calcium.

Another "fun fact" that I picked up yesterday from Bugbee was that purple stems may be from low media temps. I've "always" had purple stems and never gave it a second thought but the light went on (pardon the pun) when I heard that because I grow in hydro and my res runs at 67 or 68°. The OP's air temp is 75, on the surface. Might be interesting to get a temp in the soil.

cdgmoney250 said:

looks like the plants are receiving too much light for the environmental conditions, likely a VPD/transpiration issue. I would raise your ambient temps into the mid 80s and let your would dry out just a hair before your next irrigation cycle. I would also aim for 50+% for your humidity. Look up VPD Chart if you aren’t familiar. We are more concerned with leaf temps than ambient. Of your stems are starting to stripe Or turn purple, vpd being out of range is a likely culprit

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VPD? that's one thing I have not ran across or researched yet!!! and I can't just follow a rubric, I've always wanted to know "why" something works and dig in - usually excessively in most peoples eyes. Get told keep it simple all the time, but can't help trying to decipher every variable lol. I check my girls everyday and sometimes twice, the yellowish leaves were fresh new growth when I went through an overwatering about 2-3 weeks ago. Since then they've been growing much better and improving in color. I've also been watering with half the "textbook" 1/3 volume of your container, which would be 1 gallon - been giving each 0.5(1/2) gallon every 2-3 days since recovering from my overwatering. Method has kept the problems I experienced in veg away. Always looking to improve growmie, so I appreciate anyone taking time to drop their thoughts and experience!

Purple stems I'm 85% sure are strain related! I say that because my first grow with this same gen/bag seeds about 5 years ago also had purple stems branches, and about 40% of each bud was purple. That was outdoors, this grow is indoors with the same seeds from that baggie 5 yrs ago with purpling stems and branches. Here's a pic of some more seedlings I just started. The healthy stout ones have a solid purple stem, the frail stretchy ones do not yet(slight purple below cotyledons).


all seedlings germinated at the same time, 7 of 9 popped through soil at the same time. Were dribble watered in a ring midway between stem and edge two days ago, and again minutes before these pics. This time I did add 1/2 tsp FF Big Bloom, and also did lighter(I take my time)dribbling around soil edge. All 9 seedlings with half a red cup, so 6-7oz roughly.


PS. By Goly!! just pulled up a VPD guide article and DAMN. Talk about having to read thrice! haha

bignugs68 said:

VPD? that's one thing I have not ran across or researched yet!!! and I can't just following a rubric, I've always wanted to know "why" something works and dig in - usually excessively in most peoples eyes. Get told keep it simple all the time, but can't help trying to decipher every variable lol. I check my girls everyday and sometimes twice, the yellowish leaves were fresh new growth when I went through an overwatering about 2-3 weeks ago. Since then they've been growing much better and improving in color. I've also been watering with half the "textbook" 1/3 volume of your container, which would be 1 gallon - been giving each 0.5(1/2) gallon every 2-3 days since recovering from my overwatering. Method has kept the problems I experienced in veg away. Always looking to improve growmie, so I appreciate anyone taking time to drop their thoughts and experience!

PS. By Goly!! just pulled up a VPD guide article and DAMN. Talk about having to read thrice! haha

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Check out these guys. I started in VPD with their PulseGrow but use AC Infinity products now. Highly recommended.

VPD = "feels like" temp for humans.

bignugs68 said:

Purple stems I'm 85% sure are strain related! I say that because my first grow with this same gen/bag seeds about 5 years ago also had purple stems branches, and about 40% of each bud was purple. That was outdoors, this grow is indoors with the same purpling stems and branches. Here's a pic of some more seedlings I just started. The healthy stout ones have a solid purple stem, the frail stretchy ones do not yet(slight purple below cotyledons).

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<slaps self on forehead>
Yeh, there's that genetics thing!
Absolutely!

Delps8 said:

What signs are you seeing that indicate that the plant is receiving excess light?

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The simple observation that every time the light was increased the plants became more stressed.

And if you read again what I wrote: “looks like the plants are receiving too much light for the environmental conditions, likely a VPD/transpiration issue.”

Hopefully that clears that up.

Delps8 said:

I do see leaves that have look to be low on fertlizer, based on their light color, and some of the leaves are turning down which is, I believe, a symptom of overwatering or improper watering.

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Could possibly be over-watering, but to me it looks more like the plant just isn’t drinking properly. Soil doesn’t look soggy, and the plants are large enough to snap out of an over-water situation quickly if the environment is in order. Thats why I recommended letting the soil dry out a bit before the next irrigation cycle.

Delps8 said:

The problem with the "turn the light down because it might be excess light" is that we're dealing with modest amount of light to begin with and, since light is the only way the plants can create "food", lowering light that are not in excess will reduce the plants' ability to generate energy which may exacerbate the problem.

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You’ll note that I didn’t recommend adjusting the light levels. I recommended adjusting the temperature higher into the mid 80s and adjusting humidity higher. I also mentioned looking into VPD, because I personally have found that it works in helping alleviate certain transpiration issues, including overwatering, and other abiotic stresses. The warmer temps cause more water to evaporate from the soil, increases leaf temperature, and plants generally photosynthesize more efficiently at warmer temps (to a point).

Delps8 said:

VPD being out of range causes purple (red) - that's a new one. Nothing I've read on VPD deals with changing color of stems. VPD being too high tends to cause nutrient imbalances, typically calcium.

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Phosphorus deficiency typically causes Purpling in stems, petioles, and leaf veins when it is not an inherent trait of the strain. Phosphorus demand can outpace uptake during certain stresses.

Phosphorus deficiency typically causes Purpling in stems, petioles, and leaf veins when it is not an inherent trait of the strain. Phosphorus demand can outpace uptake during certain stresses.

VPD being out of range can cause transpiration issues, affecting stomatal opening, lowering the rate of photosynthesis, which can reduce water uptake making the soil take longer to dry out between irrigation cycles. When the rate of photosynthesis is lowered, but photons are still raining down on the canopy, the plant has to put energy into dealing with any surplus photons. This will increase nutrient demand. If demand can’t be met, deficiency is increased with higher light loads.

I’m not saying all P deficiency or purpling of stems are related to transpiration issues by any means. I’m just stating that transpiration issues can be a factor in those symptoms. Based on OP’s environmental conditions, I’d bet on it.

bignugs68 said:

Always looking to improve growmie, so I appreciate anyone taking time to drop their thoughts and experience!

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You bet! VPD was a game changer for me years back once I understood how it all ties into the photosynthetic process. Cleared up a grip of issues that most would have to told me to “just use more cal-mag, because…. LEDs”

bignugs68 said:

Purple stems I'm 85% sure are strain related!

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This is probably going to be controversial, somehow a bunch of my comments are, but I think that some plants will have a genetic predisposition for having red stems and will often fade to red, purple or black colors. But I believe most plants that turn purple before they go to senescence are in fact lacking in nutrition, or there is a soil/mineral imbalance. I apply the idea of different bodies, different needs, similar to different strains or even different phenotypes of the same strain. This isn’t the thread to go on about it, but if you end up going down the soil mineral balancing rabbit hole, it runs pretty deep and is illuminating (pun)

Purpling: you can also argue purpling being an effect of the high irradiation response; too much light intensity with not enough heat creates anthocyanin (purple pigment) to accumulate in stems/petioles.

The plants in this case looks a bit hungry to me, either a bit more feed but much better to try to get it to transpire properly using VPD. These plants looka bit saggy and sloppy in their posture, when they are drinking properly you see more of a plant/leaf boner. RH also seems a vit low for early flower.

All great stuff everyone! I've considered also, that maybe this strain is more susceptible to purpling bc of(now that I know of it ) VPD, or it's hungrier than average for phosphorus?? So All 3 grow efforts I've been under-supplying that nute??? Lol I can chase myself in thought circles all the timewgen all my knowledge is quotes lol; I've read a lot - but dont have the "know" experience.

Purpling: you can also argue purpling being an effect of the high irradiation response; too much light intensity with not enough heat creates anthocyanin (purple pigment) to accumulate in stems/petioles.

The plants in this case looks a bit hungry to me, either a bit more feed but much better to try to get it to transpire properly using VPD. These plants looka bit saggy and sloppy in their posture, when they are drinking properly you see more of a plant/leaf boner. RH also seems a vit low for early flower

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@Rocket Soul , the antho's is def a thing, but I don't believe applies here because this is the first week I've had the temps stay below 80 consistently. Since seedling, my mains have been in 74-83.X during light. Maybe dropped to 69 at night? But def now colder as my ambient is always around that or 72. My dumbass just didn't realize "oh look, tent base flaps that will let her breathe instead of being super negative pressured" and walla - 75-78 is the norm now

bignugs68 said:

I've considered also, that maybe this strain is more susceptible to purpling bc of(now that I know of it ) VPD, or it's hungrier than average for phosphorus?? So All 3 grow efforts I've been under-supplying that nute???

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I just wanted to clarify this for you. There could be so many different factors as to why you could have a phosphorus “deficiency”. This doesn’t necessarily mean that there is not enough of the mineral in the soil. Purpling is just a symptom of a cause. This is outside the scope is this thread, but do a little research on phosphorus availability in soil, and phosphorus roles in plant growth and that will give you some good insight.