Just got a new Light and need help

[jdogrulz]

Hey everyone!
I just got a new light yesterday, it is the VIPARSPECTRA XS1500 Pro.
I woke up this morning and found that some of my plants looked like they were burnt. (see photos)
I set the light to manf. recommended settings which is 11.8" from plant and light set to 100%.

So today I set the height to 14" and left it at 100%.

Does anyone have any suggestions before I end up with cooked weed...lol

 

[improvise]

Ouch
Start higher and lower gradually . And lower the intensity of light and gradually go higher.
when i first saw the pics i thought it was nute burn.
Folks here will opefully solve the prob.
regards

 

[SmokingWings]

To me it looks like some sort of deficiency or other issue that has been building for awhile. I do not see the usual signs of heat issues such as the fingers of the leaves curling like a taco shell or a canoe. While some of the finger points are curling like a dragon's claw most of them are still straight out.

Do you have any photos of the top of the canopy which you took in the last couple of weeks while you had the other light? Can you tell us the name of the previous light?

 

[jdogrulz]

Ouch
Start higher and lower gradually . And lower the intensity of light and gradually go higher.
when i first saw the pics i thought it was nute burn.
Folks here will opefully solve the prob.
regards

Thanks for the input!
I have raised it to 14", but was not sure if I should lower the intensity also.

 

[jdogrulz]

To me it looks like some sort of deficiency or other issue that has been building for awhile. I do not see the usual signs of heat issues such as the fingers of the leaves curling like a taco shell or a canoe. While some of the finger points are curling like a dragon's claw most of them are still straight out.

Do you have any photos of the top of the canopy which you took in the last couple of weeks while you had the other light? Can you tell us the name of the previous light?

Thanks much for the reply!

Well, it was looking just fine until I put the light in, and I have not changed the NUTEs at all.

Yes, I had the VIPARSPECTRA 300W AND 2 55k E27 LIGHTS ON THE SIDES. All lights were kept 12" above flowers. I will look for some photos from before and post.

 

[jdogrulz]

Ok, now I feel stupid :-(
I took some photos last night after I installed the new light and if you zoom in you can see that the leaf is already yellowing, so it must be NUTE burn, but I have not changed anything.

Anyway, thanks again everyone and now I am going to put on my dunce cap and go sit in a corner

 

[SmokingWings]

I took some photos last night after I installed the new light and if you zoom in you can see that the leaf is already yellowing, so it must be NUTE burn, but I have not changed anything.

Anyway, thanks again everyone and now I am going to put on my dunce cap and go sit in a corner

Don't worry about it. It is human nature to ignore slowly developing preexisting conditions until the grower changes something else like you did. As for the "dunce cap" you can put it on the head of witch doll and be ready for fall holidays like Halloween.

Back to the condition of the plant. I doubt that it is a fertilizer burn; more likely a deficiency. And, the plant has gone into flower, maybe starting about 2 weeks ago. When a Cannabis plant starts the flowering stage it starts to need more nutrients than it did while just growing leaves and stems though some of what I am seeing probably started several weeks ago.

Going to be hard to reverse the conditions but it is possible to stop it from getting worse or taking over more leaves.

The photo below is of one of my plants that I allowed to grow into and between the LED lamps on one of my lighting fixtures. It is easy to see where the fingers of the leave got within a couple of inches of the light and heat. After a couple of days I lowered the plant down from the lights and let it continue growing.

light-burn02.jpg

• SmokingWings
• Sep 16, 2022

light burn 2 inches from LED pod, moved plant away 40 hours before photo taken with P&S.

 

[jdogrulz]

Don't worry about it. It is human nature to ignore slowly developing preexisting conditions until the grower changes something else like you did. As for the "dunce cap" you can put it on the head of witch doll and be ready for fall holidays like Halloween.

Back to the condition of the plant. I doubt that it is a fertilizer burn; more likely a deficiency. And, the plant has gone into flower, maybe starting about 2 weeks ago. When a Cannabis plant starts the flowering stage it starts to need more nutrients than it did while just growing leaves and stems though some of what I am seeing probably started several weeks ago.

Going to be hard to reverse the conditions but it is possible to stop it from getting worse or taking over more leaves.

The photo below is of one of my plants that I allowed to grow into and between the LED lamps on one of my lighting fixtures. It is easy to see where the fingers of the leave got within a couple of inches of the light and heat. After a couple of days I lowered the plant down from the lights and let it continue growing.

light-burn02.jpg

• SmokingWings
• Sep 16, 2022

light burn 2 inches from LED pod, moved plant away 40 hours before photo taken with P&S.

"As for the "dunce cap" you can put it on the head of witch doll and be ready for fall holidays like Halloween." Thats a great tip and I will do that...LOL

I dont think it is a deficiency because I am using the BIOBIZZ feeding schedule and I always stick to it like clock work. Normally you only use half of what the Manf. suggests but I use the full amount of what they say, and like I said I have not had any problems before. but there is always that first time

You are close, they have been in flowering stage now for 3 weeks, well this week will be 4.

I will try and flush this little gal and and then give her some fresh NUTES in a couple of days to see if that helps.

 

[bluter]

you can run the whole grow at 18-24 inches from canopy. as they stretch from 24 up to the 18 inch mark raise the light to 24 until they stop stretch then leave it 18 from the top.

normally you'd start the dimmer lower and raise intensity through veg. by the time you hit flower you be about 90-95% on the dimmer.

never run 100%, it will decrease the lifespan. you can more than double the life of the rig running 5-10% under with no difference in yield.

with a new light in flower start at about 75% to let the plants get used to the extra intensity. slowly ramp it to 90% over a wk.

 

[jdogrulz]

you can run the whole grow at 18-24 inches from canopy. as they stretch from 24 up to the 18 inch mark raise the light to 24 until they stop stretch then leave it 18 from the top.

normally you'd start the dimmer lower and raise intensity through veg. by the time you hit flower you be about 90-95% on the dimmer.

never run 100%, it will decrease the lifespan. you can more than double the life of the rig running 5-10% under with no difference in yield.

with a new light in flower start at about 75% to let the plants get used to the extra intensity. slowly ramp it to 90% over a wk.

Thanks for the great info, I really appreciate it!

As far as running it at 90%, I cant. One of the things that I noticed right away that I did not like is that the controls only allow for 6 levels, 0-20, 40, 50, 60, 80 and 100, and I think 80% is too low for the flowering stage.

We will see. I will do as you said and try different things until I get it figured out.

 

[bluter]

As far as running it at 90%, I cant. One of the things that I noticed right away that I did not like is that the controls only allow for 6 levels, 0-20, 40, 50, 60, 80 and 100, and I think 80% is too low for the flowering stage.

that sorta sucks. if you can roll it back even 5% you'll extend the life of the rig immensely.

 

[Delps8]

Your plants are in flower and, if the grow is in good shape, it should be able to handle the PPFD that light is putting out.

Light manufacturers have to be conservative in their recommendations. If not, the body of growers following their recommendations will all damage their plants and no company wants that.

The other issue is that, per the PPFD map for that light, it's generating a max of 900µmol±. Sure there's, a big red 1000 circle but that's called "marketing".

In the top picture, the damaged leaf is below other leaves that are not damaged. When a plan is exposed to too much light, the leaves closest to the light are receiving the most light and are the most damaged.

Looking at the PPFD map below, there's very little change in PPFD between 12" and 14" so, if the issue was excess light, you would still see problems because those leaves have been killed and leaves adjacent or below would show extreme photo-avoidance reactions, either canoeing/tacoing or rotation of the leaves around the petiole, similar to how a Venetian blind is rotated. I'm not seeing that so I'm doubtful that it's a function of too much light.

The XS-1500 Pro is a superb product and, since crop yield and quality increase as light levels increase, up to the light saturation point, if you want to get the most out of your plants, you will want to feed them well.

You can run a grow at 24", turn the dimmer to 20%, etc. but growers lose more yield by giving there plants not enough light than they do from giving their plants too much light.

In many cases, nutrient "burn" is an imbalance which is a symptom the other conditions of the grow being out of whack. Sure, we sometimes mix nutes incorrectly or give the plants to many chemicals but quite often (about 50% of the time according to two industry sources) it's because something is out of whack.

If you're so inclined, run through the items in the graphic below and post the values. Having temperature and RH out of range is very common — what temp and RH are seeing in your tent?

 

[Delps8]

Ok, now I feel stupid :-(
I took some photos last night after I installed the new light and if you zoom in you can see that the leaf is already yellowing, so it must be NUTE burn, but I have not changed anything.

Anyway, thanks again everyone and now I am going to put on my dunce cap and go sit in a corner

The new light is at a higher PPFD which will tend to increase temperature and drop RH, right?

The plant has to react to that by transpiring more (putting out more water). It's basic physics that "everything" flows from high to low so when the grow environment gets hot and dry, plants have to give off more water. That means they have to take up more water and that means more nutrients will be taken up.

We don't know for sure that there was a change in the temp and/or RH (that's for you to share) but, introducing a new light and cranking up the power might have caused the problem but because the tent got warmer, not because there's more light.

That's where having a journal and taking measurements can come in really handy.

 

[Scottay]

I have the exact same light. It's really strong. I'm only running my light at 25% and my plants are doin great. I'm only 11-12" away from the canopy. Good luck. I hope the rest of your grow goes well!!

 

[jdogrulz]

Hey guys, thanks much for all of the great info!!
Sorry I have not had time to reply but been very busy as you can see in my photos.
I decided to upgrade to a 100x100x200 Tent! WOW! What a difference! I can finally work around in the tent without breaking my back, which is good since I just had my 6th OP on my back

Well my first grow is now going good and they are budding up nicely. We are at week 7, day 49, so ca. 1 - 1.5 weeks left.

Today the Pineapple Express has started her DWC grow and is DAY 1! Things are so much easier with the new and bigger tent! This is my first attempt at DWC, so I hope I dont screw it up...LOL.
I now have the seedlings on one side under the new light, and turned down to 50%. The flowers on the other side under the old light. This light has provided me some nice grows in the past so it should be fine for finishing these flowers.

Going to start another DWC just as soon as the seeds are ready which should be in a couple of days.

I finally figured out why my Germinations were taking so long and they always looked so small and stunted, so I went back and looked at everything I was doing again and then it hit me, I was de-chlorinating the tap water, but I was not bringing down the PH, because my tap water can be anywhere from 9-10.8, so I am sure it was slowing them down and stunting the growth. Now that was just with putting them in water and paper towels for germination, but I always adjusted the PH with the NUTES. So I started adjusting the tap water to 5.8-6 for everything and things are going much better.

 

[jdogrulz]

The new light is at a higher PPFD which will tend to increase temperature and drop RH, right?

Nope, I thought it would but it did not make any difference. When I wrote the OP it was 81/51.
And today we have had our hottest day and it was still ok. I have the RH pretty much always between 50-61 and as of yet it has not been any higher.

 

[Sativa1970]

Light is the limiting factor for most grows. Increasing the light increases the plants demand for nutrients and all 8 of the other factors.

In DWC PH is the foundation for the entire system. If everything is a bit off but PH is good the plant will grow. If everything is perfect but PH is off the plant will not grow. When your PH and EC are unchanged, but water level drops, you are dialed into the nutrient mix the plants needs.

 

[Delps8]

87° and 54%? That's very harsh conditions for cannabis.

VPD is a very good way to express combinations of temperature and humidity. This page is a good explanation of VPD.

VPD is akin to "feels like" for humans. At 87 and 51, your plants are functioning in a desert-like environment.

In veg, cannabis grows best when VPD is 1.0 while VPD in flower should range from 1.2 to 1.5 ( prefer 1.2 or 1.3). Check the intersection of 87 and 54 and your plant is working in a VPD of 1.7±.

To function in a hot and dry environment like that, your plants have to throw off a significant amount of water. Like humans, plants can be described as "bags of water" and when the air is hot and dry, water will flow from that a bag of water to the outside air. That's because there's not a lot of water in the air but there is a lot of water in the plant <== that means that the "deficit" is high and, in nature, everything tends to move from high to low.

With all that water leaving the plant, the roots have to take up a lot more water than normal and when plants take up a lot more water than normal they also take up a lot more nutrients than normal.

In terms of VPD, your plants will do better growing in an environment that is about 10° lower.

The other reason to lower the temperature is that at 87° you're "decimating" your cannabinoids The word "decimate" is a paraphrase of how the loss of cannabinoids was described when temperature of the flower tops of cannabis plants exceeds 78°.

Mitch Westmoreland, a cannabis researched studying under Bruce Bugbee, did a video on growing hemp about three years ago and he mentioned that…

[searches for notes and finds them]

I've grown my plants in the low to mid 80's and, while some of the yields have been prodigious, they haven't had the kick that I associated with premium bud that I've bought from resellers here in CA. In response to the Westmoreland videos, I'm changing my growing processes and am replacing my flower light so I can provide my plants with 1100µmol± as well as keeping the tops of the flowers <78° in flower.

Below are the notes I took on the Westmoreland video on hemp.

Does Hemp Need Extra Water and Fertilizer?
Mitch Westmoreland


Plants grown at 73 and 84 degrees. Plants at 84 were taller but colas were smaller in girth.

At 84 little but taller, a bit more vegetative biomass. Yield wasn't all that affected by the increase tempearature. At 84°, cannabanoids were roughly 1/2 of what they were at cooler temperatures.

Suggest that the optimum is between 70 and 80.

Fertilizer
You've probably come across hundreds of companies promising to boost yield. They "lack a theoretical basis" and you'll probably end up just throwing away money and excess nutrients that will end up polluting our nice rivers.

We recomend that you fertilize it just as you would tomatoes. This is a good comparison there's nothing particularly special about hemp.

One of the big claims that you'll see coming out out of the cannabis industry is that high phosphorus will increase yield and will increase cannabanoid content. We've tested this.

We look at a range of phosporus treatments ranging from borderline deficient to excessive. We found no significan difference, especially as we move toward the rates recommended by the cannabis industry. This has implications because phosporhus is a potent pollutant in our environment.

What we're trying to do is get growers to use as little P as we can while still getting a good crop.

Drought stress
In veg - they're very resiliant. Got to the point where they were severely wilted. They recovered so that it seems as if nothing happened. Hard to see which one's were stressed and while ones were well watered.

In flower - yellowing and dropping of leaves and reduction in yield. CBD and THC does not make production increase.

Temperature - yield increased slightly. CBD and THC plummeted - "cut in half basically". We don't have a good explanation for this right now. We're going to ssee if we can reproduce this and see if we can come up with an explanation for what's going on."

Per my notes, above, high temps will result in a signficant loss of THC and CBD (he doesn't mention terpenes here). Westmoreland continued his research in this area and, in early 2024, released two videos in which he discussed some of the aspect of the work that he had presented for his PhD thesis.

This graphic, the growth rate which is substantiated in other published research, it why I recommend keeping light levels as high as the plant will tolerate. Other research shows that the result is not quite linear but the research indicates a direct cause/effect relationship between increased light levels and crop yield, assuming that light is the limiting factor.

My advice, read up on VPD (you need an IR thermometer to get your leaf surface temperature), drop your tent temp and LST, and adjust your RH so that your VPD is 1.2. That won't bring back the dead tissue in the leaves but it will deduce the very high transpiration rates and that will help resolve the nutrient issue that you're looking at

 

[Delps8]

I have the exact same light. It's really strong. I'm only running my light at 25% and my plants are doin great. I'm only 11-12" away from the canopy. Good luck. I hope the rest of your grow goes well!!

At a 25% dimmer setting and 12" hang height, your plants are getting about 250µmol which is appropriate for cannabis in the seedling stage. By early veg, cannabis will grow quite well at double that value and, by mid-veg, cannabis will thrive at the 800-1000µmol level.

While your plants appear to be "doin great" at that light level, if the light level doesn't increase, cannabis plants will stretch to get more light and you will end up with tall, slender plants with few branches, a limited number of large leaves, and a significantly reduced yield.

 

[jdogrulz]

Light is the limiting factor for most grows. Increasing the light increases the plants demand for nutrients and all 8 of the other factors.

In DWC PH is the foundation for the entire system. If everything is a bit off but PH is good the plant will grow. If everything is perfect but PH is off the plant will not grow. When your PH and EC are unchanged, but water level drops, you are dialed into the nutrient mix the plants needs.

Thanks, yeah, I am keeping a close watch on them both (PH & EC). I have watched probably 100 videos on how to DWC and of course everyone does it a littlbe bit different but one thing they all have in common is making sure the PH and EC are always spot on.

What is wierd is that I noticed when I set my PH on my nutes, say 6.0, the next day it is back up to 7 or 8 and not sure why, so I am keeping a really close eye out for PH. I dont want my first time to be a bust.