Will a brighter LED light improve the frostiness of the bud?

Rocket Soul · Jul 31, 2025

HydroLynx said:
Is that 1.81 W/m2 the total wattage of the UV light or the wattage of the UV spectrum of the light?

If i understand the study correctly: nor output nor total watts of uv light; measured uv intensity at cannopy level.

jimihendrix1 said:
I just read about a study that was done, Last Year, released Jan 1 2025, using UVA/B, and the scheme that was most affective, and didnt mess with production ect was.
1.81W Sq/m, and UAV/B was 99/1.
They used multiple lighting strengths, and ratios of UVA/B.
They also increased 3 different chemicals by no less than 22%.

The study tested three UV light spectra at five intensity levels, analyzing their effects on photomorphogenesis, inflorescence yield, and the chemical profile of cannabis. While none of the UV treatments altered cannabinoid concentrations, significant changes were observed in terpene profiles under certain conditions.

Notably, the UV treatment labeled L3_1, which emitted UVA:B at a 99:1 ratio and an intensity of 1.81 W/m², increased concentrations of key terpenes. Compared to the control group without UV exposure, linalool rose by 29%, limonene by 25%, and myrcene by 22%. This treatment maintained consistent yield and cannabinoid levels, making it the most practical option for commercial cannabis cultivation.

Additionally, UV exposure affected growth and leaf morphology. Higher UVA levels increased leaf area, while elevated UVB levels resulted in smaller leaves. However, only the L3_1 treatment was deemed viable for large-scale cultivation due to its ability to enhance terpene profiles without compromising plant yield or cannabinoid content.

The findings suggest that selective use of UV light could help optimize terpene production in cannabis, offering potential benefits for both growers and consumers.
Below is the study’s full abstract. The full text of the study can be found here.

Nice study but a lot to chew thru, and some rather strange stuff: like no mention of what light or spectrum they use for wither main light or uv (though ratios; but uvr8 gene uvb reactivity is hugely varied with which nm targeted).
Only linalool was deemed raised to the point of statistic significance p:0,05, but theres a very strong trend in the rest of the terps. Though if we include the non significant terp numbers then we also have to consider that the L3 control had higher thc than the L3 uv treated groups. Which is strange. Main thing here is that it seems like a little uv goes a long way, even if mainly uva; at least as far as smells and with low light intensity.

medidedicated · Jul 31, 2025

Im kinda shooting for the same thing this grow but taking a short cut thru genetics. A lot of people getting frosty buds with slurricane #7 S1’s so I got 6 going right now. Just seeing what does it for my environment with better genetics.

Wouldnt then be a good time to see what spectrums to add to get even more frost than that? Youll be the frostiest bag on the block thats for sure. If you want to keep the quality coming Id touch on cloning and mother keeping skills so you always have it for a good while. Before sadly it just is lost so I think preserve or breed into offspring is the only to options.

Its a on going thing it gets deep. Running perpetual clones really set me up to be ready to work on bigger projects. The perpetual line up just allows faster operation so 6 pheno hunt is really like 12 phenos in one grow cycle from start/finish.

Its not as simple as here, buy this uv light and get better results. As the conversation goess you see its just easier to get better genetics first.

Delps8 · Aug 3, 2025

Star Dog said:
I use 650w led @10/12" using a uni t light meter with the ppfd app it reads between 1150/1250.
View attachment 5475379
I've got my light hemmed in with mylar it's painfully bright.
View attachment 5475380
They may look a little rich but they're OK with the light levels.

I've seen some minor light stress but only white tips of leafs sorta like they'd been over fed but light in colour.

That's a really nice looking grow. No photon is going to waste!

What are you nutrient levels?

I've been growing at 1k± for a few years and have run into issues when I go over 1100. Over the course of a grow, some of the buds will hit mid 1100's but these numbers are pretty standard for later in the grow (day 86) with an average of 1035.

I measure light using an Apogee and sample multiple spots. I take readings pretty much daily exception being in late flower when it's always the same numbers 'cause nothing is changing.
My experience has been that Gorilla Glue strains look pretty funky at these light levels though, after spending a few hours reviewing my grow processes, one change that will deal with that is to increase EC. I fed chatGPT the dimensions and mass of some of the buds from my most recent run and they are "average" but, at 1kµmol, they should be "dense". I've been running up to 1.6 but will be using 2.0 or 2.2 in future.

I've attached a couple of papers that discuss growing at >1k. Perhaps they'll be of interest.

Star Dog · Monday at 12:53 AM

Delps8 said:
That's a really nice looking grow. No photon is going to waste!

What are you nutrient levels?

I've been growing at 1k± for a few years and have run into issues when I go over 1100. Over the course of a grow, some of the buds will hit mid 1100's but these numbers are pretty standard for later in the grow (day 86) with an average of 1035.

View attachment 5475750

I measure light using an Apogee and sample multiple spots. I take readings pretty much daily exception being in late flower when it's always the same numbers 'cause nothing is changing.
My experience has been that Gorilla Glue strains look pretty funky at these light levels though, after spending a few hours reviewing my grow processes, one change that will deal with that is to increase EC. I fed chatGPT the dimensions and mass of some of the buds from my most recent run and they are "average" but, at 1kµmol, they should be "dense". I've been running up to 1.6 but will be using 2.0 or 2.2 in future.

I've attached a couple of papers that discuss growing at >1k. Perhaps they'll be of interest.

Hey bro, I can get by with 1.8ec for most strains but I've a couple that have needed 2.2ec to get them on track fwiw gorilla glue is one of those...that and 2 others were fed from another reservoir with 2.2ec

I don't use dtw anymore but when I did reading the run off suggested more light needs more nutrient.

Edit....looking back I can see I had problems with plants yellowing in previous crops, I was using 1.8ec I didn't think it possible to be underfeeding but someone suggested it and i had nothing to loose by trying and woohoo! it did fix the yellowing for those and following crops.

S

Post in thread 'The UK Growers Thread!'

Jul 24, 2024

I've got the same yellowing plant issue again with 3 autopots, today I got them to the front to give me access to them for hand feeding.

Ec and ph are good so it doesn't leave a whole lot?

I tested calmag on one plant (front right) and lol, well you see it lol.

The issue doesn't show up great in that pic.
Cheese dipz it's getting worse day on day?

For comparison Bluchi v3

I need to go back to the drawing board with the autopots?

@conor c is it within the realms of possible they're too wet with 50/50 coco and perlite?
Does that plant at...

I can't remember the finer details but adding mylar increased the light intensity enough that I had to increase the ec to deal with it.
A reading without mylar...

A reading with the mylar.

It's a significant increase around the perimeter in particular, the centre spot worked out to a 7% increase using mylar.

With the increase around the edges it somewhat cooled the hot spot and evened out light readings across the canopy it was £20 well spent I thought.

DoubleD5374 · Monday at 9:30 PM

HydroLynx said:
Thanx for the input guys

I looked at Dr Coco for Cannabis and they said 700 umol is perfect, anything above that causes stress. But im still wondering if that stress is the good kind which makes bud frostier

I’m here to say that I’m around 1000-1300 umol , depending on the flower - not every is the same height . They’re plenty frosty . That being said I’m flowering in extremely high humidity with tons of air exchange and no added co2 .

I’ll post a picture of my tent to show lower branches are in the 6-700 range , tallest branches exceed 1300 in spots . This is done with a phantom photo bio advanced quantum par meter - and is almost identical to the readings I get from the apogee as well .

I flipped on July 8th , these flowers are some of the taller ones , getting more umols then lower bud sites . I’m not seeing any adverse signs of stress from the plants . They’re loving life

Delps8 · Tuesday at 8:51 PM

DoubleD5374 said:
I’m here to say that I’m around 1000-1300 umol , depending on the flower - not every is the same height . They’re plenty frosty . That being said I’m flowering in extremely high humidity with tons of air exchange and no added co2 .

I’ll post a picture of my tent to show lower branches are in the 6-700 range , tallest branches exceed 1300 in spots . This is done with a phantom photo bio advanced quantum par meter - and is almost identical to the readings I get from the apogee as well .

I flipped on July 8th , these flowers are some of the taller ones , getting more umols then lower bud sites . I’m not seeing any adverse signs of stress from the plants . They’re loving life

That's a huge amount of light. The visible symptoms are canoeing and leaves rotating around the petiole but there's another condition called "photoinhibition" (long description). I haven't run into it but it's harder to spot because the symptoms can be hidden. Not trying to rain on your parade but it's something to be aware of.

Thinking of rain…the heat's over, right?

Hollatchaboy · Wednesday at 4:59 AM

Delps8 said:
That's a huge amount of light. The visible symptoms are canoeing and leaves rotating around the petiole but there's another condition called "photoinhibition" (long description). I haven't run into it but it's harder to spot because the symptoms can be hidden. Not trying to rain on your parade but it's something to be aware of.

Thinking of rain…the heat's over, right?

Screenshot_20250806_055928_One UI Home.jpg

On my Google news feed this morning. Lol

jimihendrix1 · Wednesday at 9:03 AM

Im in the Red Zone. I may hold off on starting more, until this round of heat is over, but, may still start them.

medidedicated · Wednesday at 9:16 AM

I got challenging traits to find so I have to grow year round. Just a portable ac and Im good. Energy sky high but its working out. My grow room was the coolest ground floor room when it was 92F.

Delps8 · Wednesday at 10:09 AM

Hollatchaboy said:
View attachment 5476060

On my Google news feed this morning. Lol

Ouch.

Let's hope things play out with their normal level of accuracy. ;-)

DoubleD5374 · Wednesday at 3:40 PM

Delps8 said:
Ouch.

Let's hope things play out with their normal level of accuracy.

I’ve got lots of ac in my home - which definitely helps , I still see 80 degrees at the top of the canopy on some evenings . The temps honestly don’t bother me , I ran a greenhouse last year where temps were insanely high . 85+ outside meant 110+ inside that hoop house . We had sprinklers kicking on , every 20 minutes or so , outside spraying directly onto the greenhouse material , to cool it down on hot days , and it worked excellent as well as not increasing humidity like internal misting systems do .

Humidity is starting to creep up in my tent though , to uncomfortable levels “flowers are getting larger “

So even though I’m strapped cash wise , looks like I’ll be buying a dehumidifier to work with my ac infinity controller - to get levels back to comfortable . I noticed today I was at 70% lights off . I have several fans circulating in there , but at that level I feel as though I’m playing with fire and safest bet is to drop it down with a dehu asap

Wethead · Wednesday at 4:33 PM

medidedicated said:
Its genetics. More light will just fry it and possibly turn less frosty. I do about 700-800ppfd. Maybe even less.

I am using a single light 2’ x 4’ AC Infiniti grow tent. It does not have the light numbered as you are speaking of it here.

The controller has between one and 10. How can I tell what the light output is on the settings?

medidedicated · Wednesday at 4:41 PM

Wethead said:
I am using a single light 2’ x 4’ AC Infiniti grow tent. It does not have the light numbered as you are speaking of it here.

The controller has between one and 10. How can I tell what the light output is on the settings?

I dont even measure it I just read the plants. Reading them takes time and practice. I still am learning. Lights are easy to read tho thatll probably be the first thing you learn.

You can use a lux meter for android or iphone in a downloadable app. Then convert it. I used a site. Honestly its better to just buy a actual ppfd meter so it just tells you what it is.

Yes this is a fustrating thing I recently noticed. Most lights now days are in pre set settings. The one I love is called analog styl dimmer it turns freely. This was a problem for me in veg as I guess my plants just want suuuper dim lighting, literally almost in the off position.

So I only have like one light to choose from. Since I want bar lights. Migrow might be the next best bet as they keep changing things like detachable driver, now being fixed to the light. I might end up making my own lights some day. The potential can be greater if you went down that route anyway.

Delps8 · Wednesday at 5:55 PM

Wethead said:
I am using a single light 2’ x 4’ AC Infiniti grow tent. It does not have the light numbered as you are speaking of it here.

The controller has between one and 10. How can I tell what the light output is on the settings?

It's based on the output of the light. Check the manufacturer's website and that should have information to help you use their lights.

A lot of growers use lux meters. They're inexpensive and will get you close enough. In most cases, the recommended values from the manufacturer are OK but, for whatever reason, with AC infinity their lighting recommendations…"need some refinement".

What model light are you using and how old are your plants? If you give me some info, I can get you in the ballpark.

medidedicated · Wednesday at 6:02 PM

I have my mars hydro fce1500 at 75% about 12-16” away from tops. I just give them enough to be happy before I see some rejection then back off a bit. Usually 100% but this run idk its just hot its summer. Again just going with flow.

Delps8 · Wednesday at 6:08 PM

DoubleD5374 said:
I’ve got lots of ac in my home - which definitely helps , I still see 80 degrees at the top of the canopy on some evenings . The temps honestly don’t bother me , I ran a greenhouse last year where temps were insanely high . 85+ outside meant 110+ inside that hoop house . We had sprinklers kicking on , every 20 minutes or so , outside spraying directly onto the greenhouse material , to cool it down on hot days , and it worked excellent as well as not increasing humidity like internal misting systems do .

80's on tops of the canopy, that's downright chilly compared to a few weeks ago!

I'm glad to see that. A few degrees lower and you'll be in like Flynn.

It was nice and cool this AM, in line with the weather we've had to, frankly, a couple of years. So, "Just when you thought it was safe…"

Bluelab is the temperature at the Bluelab monitor, right next to the tent. The seeds for my next grow are safely tucked away in the fridge for another month.

DoubleD5374 said:
Humidity is starting to creep up in my tent though , to uncomfortable levels “flowers are getting larger “

Yeh, that's no bueno. Big nugs are prime real estate for botrytis.

DoubleD5374 said:
So even though I’m strapped cash wise , looks like I’ll be buying a dehumidifier to work with my ac infinity controller - to get levels back to comfortable . I noticed today I was at 70% lights off . I have several fans circulating in there , but at that level I feel as though I’m playing with fire and safest bet is to drop it down with a dehu asap

Absolutely. Fans will help prevent the spores from settling but there's still the RH issue. AC Infinity is finally coming out with dehumidifiers but only the little one is in production. The others are "Q4". :-(

I wrote them for specs on the mid-range one and "Sadly, we do not have the technical specs available at the moment, my apologies. I would recommend checking back in about 1-2 months for another update. " so sayeth Ashley.

"Here! Take my money!"

"Totally cool. I'll get back to you." Very California.

Keep the faith (and get that dehu running!).

DoubleD5374 · Wednesday at 8:41 PM

Delps8 said:
80's on tops of the canopy, that's downright chilly compared to a few weeks ago!

I'm glad to see that. A few degrees lower and you'll be in like Flynn.

It was nice and cool this AM, in line with the weather we've had to, frankly, a couple of years. So, "Just when you thought it was safe…"

Bluelab is the temperature at the Bluelab monitor, right next to the tent. The seeds for my next grow are safely tucked away in the fridge for another month.
View attachment 5476148 View attachment 5476151

Yeh, that's no bueno. Big nugs are prime real estate for botrytis.

Absolutely. Fans will help prevent the spores from settling but there's still the RH issue. AC Infinity is finally coming out with dehumidifiers but only the little one is in production. The others are "Q4".

I wrote them for specs on the mid-range one and "Sadly, we do not have the technical specs available at the moment, my apologies. I would recommend checking back in about 1-2 months for another update. " so sayeth Ashley.

"Here! Take my money!"

"Totally cool. I'll get back to you." Very California.

Keep the faith (and get that dehu running!).

lol we’re gonna be seeing 5 straight days of 92+ weather here, and 10 more of 85+ so it’s about to get spicy

Jylhavuori · Thursday at 12:23 AM

Just came here to brag about my "flowering" LED bar. At first I was really sceptical of this one. Lumen King eco line 400W (75x75cm) designed for 1m².
My tent is 90x90cm. These bar lights can be put much closer than quantum panels, up to 6". Blue peak is quite high ~500nm, and only has 660 red added. Now at full power 8-10" distance to tops. Previous weeks were 320W.
28-30°c, RH 40-65% (mostly around 29°c 50%)

Tops getting 1300-1400PPFD. I know it's an overshoot by at least 200 but this way penetration is good for lower canopy, and there's much of it.

Spectrum

Screenshot_20250807-091129_Samsung Notes.jpg

Flowered 34 days. DWC, GHE+rhino skin

Its more about choosing your fight: vegging or flowering - unless you put a fortune to a tuneable spectrum. For example, my light cost 175€! Lol

Will be hard to talk me out of this panel.. and yes, it does vegetative just ok. But, as a final mention, brightness as a factor above 800PPFD is useful and important merely when the other factors are aligned IMO.
[Nutrients, (+substrate),climate]

Delps8 · Thursday at 12:28 PM

Jylhavuori said:
Just came here to brag about my "flowering" LED bar. At first I was really sceptical of this one. Lumen King eco line 400W (75x75cm) designed for 1m².
My tent is 90x90cm. These bar lights can be put much closer than quantum panels, up to 6". Blue peak is quite high ~500nm, and only has 660 red added. Now at full power 8-10" distance to tops. Previous weeks were 320W.
28-30°c, RH 40-65% (mostly around 29°c 50%)

Tops getting 1300-1400PPFD. I know it's an overshoot by at least 200 but this way penetration is good for lower canopy, and there's much of it.

Spectrum
View attachment 5476183

Flowered 34 days. DWC, GHE+rhino skin

Its more about choosing your fight: vegging or flowering - unless you put a fortune to a tuneable spectrum. For example, my light cost 175€! Lol

Will be hard to talk me out of this panel.. and yes, it does vegetative just ok. But, as a final mention, brightness as a factor above 800PPFD is useful and important merely when the other factors are aligned IMO.
[Nutrients, (+substrate),climate]

Agree about the lights with a tunable spectrum. Current offerings are premium priced but that will change as technology advances and as market pressure puts price pressure on that feature.

In the mean time, you can get a significant boost in PPFD and an increase in red (660nm) percentage//reduction in blue % by adding supplemental 660nm lighting. The R80's will also provide

This table is based on the spectrum chart and the PPFD map for your light, as well as the PPFD map for a pair of Spider GlowR80s (660nm) supplemental lights. I've used chatGPT to do some analysis and, based on the available info, these are the estimated values when the Lumen King is running at 70% power:

Wavelength Range	Color Range	Lumen King 400W @ 70%	Lumen King 400W @ 70% + R80 @ 100%
400–500 nm	Blue	22%	15.5%
500–600 nm	Green-Yellow	28%	19.7%
600–700 nm	Red	45%	61.7%
700–750 nm	Far Red	5%	3.5%

I added a pair of R80's to my Growcraft X3 flower light. It allowed me to reduce the blue percentage, as well as reducing input power by 130 watts, and reducing ambient temperature by ~2°F.

The spectrum for my Growcraft is quite similar to yours though your light, which a "general purpose" LED, has more blue in it.

I uploaded your spectrum chart, the spectrum chart for the Growcraft, and the spectrum chart from a lighting report for the Growcraft. This the spectral percentage estimate.

Wavelength Range (nm)	Color Range	Lumen King Eco Line 400W (Spectrum 1)	Growcraft X3 Flower Light (Spectra 2 & 3)
400–500	Blue	~22%	~18–20%
500–600	Green-Yellow	~28%	~22–24%
600–700	Red	~45%	~50%
700–750	Far Red	~5%	~8%

Jylhavuori · Thursday at 1:22 PM

Delps8 said:
Wavelength Range Color Range Lumen King 400W @ 70% Lumen King 400W @ 70% + R80 @ 100%
400–500 nm Blue 22% 15.5%
500–600 nm Green-Yellow 28% 19.7%
600–700 nm Red 45% 61.7%
700–750 nm Far Red 5% 3.5%

Wavelength Range (nm) Color Range Lumen King Eco Line 400W (Spectrum 1) Growcraft X3 Flower Light (Spectra 2 & 3)
400–500 Blue ~22% ~18–20%
500–600 Green-Yellow ~28% ~22–24%
600–700 Red ~45% ~50%
700–750 Far Red ~5% ~8%

Thanks for the detailed info, again! I think my lumen king is good for penetration although it doesn't exite too much under 500nm, which I fear will not create as much terpenes as lower light frequency including, usual leds would do. Will see. It's not that big of an expense to try out what happens.

Previous plant was a bad evaluation as she was put down early. Now clones coming. Wasn't too fibery though.

Will a brighter LED light improve the frostiness of the bud?

Well-Known Member

Well-Known Member

Well-Known Member

Attachments

Well-Known Member

Well-Known Member

Attachments

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

New Member

Well-Known Member

Well-Known Member

Well-Known Member

Attachments

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Well-Known Member

Similar threads