smokey0418
Well-Known Member
Dipped a bit into co2 years ago , but growing just for myself primarily gifting flower to friends.
My consumption can’t keep up . Lol.
Great job.
Led yields..
- Thread starter Billytheluther
- Start date
My consumption can’t keep up . Lol.
Great job.
If you're getting 6 ounces out of a 2' x 4' there's something awry with your environment. I grow from seeds and find that the yield estimates from vendors (450 to 650 gm/sq mete) are accurate and, generally, conservative.
But when it comes to HPS vs LED, the attached paper sheds some light on the issue.
The research was carried out under controlled conditions. Check the paper to see how things turned out.
At issue is that yield decreases as the percentage of blue photons increases. It's not a function of an HPS light as an HPS light, rather it's because HPS was 4% blue vs a standard "white" LED that, though it varies from manufacturer and even one model of light to the next, has more blue. In some cases, a lot more blue.
Lights for small grow spaces (the XS-1500 Pro) for example, will tend to have more blue because the manufacturer doesn't want the plants to grow through the top of the, assumedly, shorter tent. I'm not privy to anyone's light design. No, it's my suspicion based on looking at lights from different vendors and trying to understand why they design their products the way they do.
On the other hand some HLG lights, which are marketed as being an HPS replacement, have low percentage of blue as well as 730nm diodes to compliment the 660nm diodes.
I think the results of the paper are that HPS generates more cannabis but at a "signficantly" higher cost. What's "significant"? To a personal grower, X% more electricity for the same yield is OK because X percent of "not much" is still "not much" but to a commercial grower who has to pay for extra HVAC as well as more $$ for electricity, it's a different story.
But when it comes to HPS vs LED, the attached paper sheds some light on the issue.
The research was carried out under controlled conditions. Check the paper to see how things turned out.
At issue is that yield decreases as the percentage of blue photons increases. It's not a function of an HPS light as an HPS light, rather it's because HPS was 4% blue vs a standard "white" LED that, though it varies from manufacturer and even one model of light to the next, has more blue. In some cases, a lot more blue.
Lights for small grow spaces (the XS-1500 Pro) for example, will tend to have more blue because the manufacturer doesn't want the plants to grow through the top of the, assumedly, shorter tent. I'm not privy to anyone's light design. No, it's my suspicion based on looking at lights from different vendors and trying to understand why they design their products the way they do.
On the other hand some HLG lights, which are marketed as being an HPS replacement, have low percentage of blue as well as 730nm diodes to compliment the 660nm diodes.
I think the results of the paper are that HPS generates more cannabis but at a "signficantly" higher cost. What's "significant"? To a personal grower, X% more electricity for the same yield is OK because X percent of "not much" is still "not much" but to a commercial grower who has to pay for extra HVAC as well as more $$ for electricity, it's a different story.
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therron
Well-Known Member
One time I pulled close to 9 lbs on a 4 x 8 table using 24 x chilled logic pucks on an SOG 1 plant per sqft. typically I pulled 8lbs. The switch from HPS was dramatic. I'll never go back to HPS. I just replaced those pucks with 2 x grand master led tarantula 5' x 5 '. I'll start posting my first run with those lights in a few days.
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Mumbeltypeg
Well-Known Member
Very nice, sativa?
therron
Well-Known Member
Barney's Farm Red Diesel. It's a 50/50, but mine definitely leaned more sativa. Sadly, the potency and terpene profile was garbage. It seems Dr. Bugbee's theory of yield dilution reigns true, most of the time. The bigger, the weaker. I grew some Corn Bread from Rare Dankness one time. The yield was horrible , but the high would melt your face off.
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Yield dilution is a well known issue. IIRC, in wheat it causes a single digit percentage drop in protein but I'd look for another cause before I blamed yield dilution. The drop in secondary metabolites would be measurable in a lab but I do not believe that it would be enough for a human to sense that "the potency and terpene profile was garbage".
The biggest threat to secondary metabolites is temperature in flower. This is a screenshot of a YT video released early this year by Mitch Westmoreland who is/was a PhD student studying under Bugbee.\
To your point, I've had plants that have provided very high yields but the potency was lacking. I believe it was due to higher temps in flower because I was keeping the plants at 80± (more + than -) and it just didn't have as much kick as other grows.
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Mumbeltypeg
Well-Known Member
That is an interesting chart.. down as low as 25c.. ok. Yeah I have usually run at 29-30c balls to walls right till the end.. started tapering off a little last couple of runs.
Mumbeltypeg
Well-Known Member
I heard Bugbee on a podcast today actually saying that turning lights and temps down at around week four (of flower) let’s the plants slow down and lets the buds take their time and develop at a better rate, which is a different way of looking at it.. I always thought Max power all the way for bigger yields and terps. Happy to change my mind though.
I agree 100% about "change my mind".
For years, I've run pH at 5.8 because it's "optimal". Bugbee recently discussed problems with iron uptake if pH gets really low (5.0±) so they run their grows at 6.0. No argument from me, per photo.
Do you have a link to that podcast? I'd like to hear what he has to say.
Westmoreland did a video in 2021 in which he briefly talked about temperature and cannabanoids but nary a peep about it from Bugbee until late last year. He did an interview and said that research was showing that "temperature would be as important as PPFD" (not a direct quote). Looking back at that statement, it looks like he was doing a little promo work for Westmoreland. He did a couple of videos early this year sharing some of his PhD research. An excellent hour of cannabis growing advice.
But dropping PPFD is surprising - why cut back on the plants' ability to make food?
Heh, that's why we have the pointy-headed guys, right?
Yeh, the cooler the better.
Based on that advice, I decided to retire my Growcraft X3 flower light, looking for something that had enough power that I could raise it to 18" and still get 1kµmol on the canopy. The Spider 4500 models had that kind of oomph, partially because they had a 430 watt driver. The PPFD numbers were excellent. I put off getting one and, wouldn't you know it, they gelded the light.
They replaced the 430 watt driver with a 320/300 and now the PPFD map is pretty much the same as the light from Mars, etc. I was not happy to see that but I suspect that they figured out that very few growers were taking advantage of the big driver so they lowered their costs.
I also tried the Mars SP3000R but that was a dead end (lengthy discussion).
After spending some time to try to replace it, I'm back to my four year old light. I just started a grow and will be shooting for 1kµmol on the canopy with a hang height of 18" which I figure is high enough to get flower top temps < 78°. If I need to, I'll drop the PPFD (that wasn't easy to write) but if a cannabis plant has gotten "lotsa light" well into flower then I'm happy to sacrifice a small amount of growth/yield in exchange for preserving more cannabanoids.
Mumbeltypeg
Well-Known Member
I am not sure how to link things I’m sorry, But it was episode 21 of “we the growers” on Apple Podcasts. Was an excellent interview all in all, the interviewer is one of the jungle boys and was asking some really good astute questions.
Thanks for that info.
Re. inserting a link to a podcast - it looks like RIU doesn't support linking to a podcast but the URL for the episode on You Tune is here:
YouTube
Enjoy the videos and music you love, upload original content, and share it all with friends, family, and the world on YouTube.
Heh, I'm glad I found this email — I'm active on two sites so sometimes it's difficult to find a specific reply.
I watch the YT video the podcast and I agree with your comments about the interviewer. He was very good in terms of adding his hands on perspective to compliment Bugbee's lab perspective.
What I didn't catch was Bugbee recommeding dropping PPFD but I will go through it again.
The big issue is that the interviewer raised the point of temperatures being different when adding CO2 vs went growing in ambient. Even though I know Bugbee's mantra is "the first enhancement is to add CO2" and all of his "paying" clients run CO2, I completely blanked out on taking that into account. Fortunately, the interviewer did raise the issue and it substantially changes things.
Some of my notes for the segment starting at 55:24
Mid 80's is with elevated CO2. If no CO2, 78-80? "Yeh, in that ballpark."
"85 could be a little hot."
With that, I changed things in my tent to keep the temp<=80 but had the interviewer not raised the ambient vs elevated issue, I don't know if I'd have picked up on it.
Re. dropping PPFD - I'll run through the video again over the weekend or if anyone else churns through it, post a timestamp when that issue is discussed. I've been growing at >1kµmol for a few years but I'm more than happy to drop PPFD if that will get a better crop.
Billy the Mountain
Well-Known Member
Sure you can.
The only significant difference in growing technique is to raise ambient temps since LEDs don't heat the leaves with IR like HID lamps.
Rocket Soul
Well-Known Member
Doesnt really have to be lower, anyone i coached who had the equipment to do the temp changes have had at least as good yield. But there is a tendency in bulb growers not to be able to wrap their head around it, humble themselves to bring temps up instead of down. And really go slow enough to not light stunt.
But yield will look smaller until the weigh in.
