Study: LED Superior to HPS for Cut Gerbera Production

Sow to Grow

Sow to Grow

Well-Known Member
Here's a snippet from a study that compares LEDs to HPS. This study from the University of Guelph evaluated the use of light emitting diodes (LED) in the production of cut gerbera. I've been told gerbera is one of the trickier flowers to grow in greenhouses because of its light requirements. Granted, it's not cannabis, but this study's data quite conclusively points at LED lighting as a superior spectrum.

We're endlessly debating various light sources and their efficacy. IMO, the most interesting part of the study is the section on photosynthetic efficiency. In the graph, you'll notice that the LED rate of photosynthesis is almost twice that of HPS between 200-1000 PPFD. Here's proof that some spectrum power distributions (SPDs) are better at photosynthesis than others.



As the scientist says in the study, "These results generate more questions than answers. Clearly, the LED supplemental lighting treatment increased the photosynthetic efficiency of the plants. This did not necessarily directly translate into increased production metrics for the cut flowers. However, the LED treatment did produce 16% more marketable flowers (ie. higher quality)."

This data is from a supplemental greenhouse, but I think it applies to indoor as well.
 
Po boy

Po boy

Well-Known Member
interesting. thanks. i've been researching LED info trying to figure out what brand to buy. this info adds to the benefits of led.
 
Cpappa27

Cpappa27

Well-Known Member
This is the first time Ive used LEDS. It seems to keep them shorter and much bushier with really tight nodes and the stalk is really thick. The leaves are really thick. The plant seems really healthy but it doesn't seem like its growing as fast as if I had an HPS. Still in veg with a 300 watt LED so IDK what I like better. I like how healthy it looks and the tight nodes but the nodes are so tight like 1/4 inch between them. Its like a shrub and that was with the lights 20 inches above the plant. When I put it too close it bleached the leaves and they died and then I pulled it up a bit and the bleaching stopped. I almost wonder if LEDs make them grow healthier but slower . IDK just my take on what Ive seen.
 
Sow to Grow

Sow to Grow

Well-Known Member
Not all LEDs have the same spectrum and there are so many other variables to consider like temperature, humidity and nutrients. How do you measure a fast growing plant? If it's by number of internodes then it sounds like your plants are doing great, if it's by height then you might consider adjusting the ratio of red to blue (if you have a fixture capable of doing that).

Yes, high powered LEDs can bleach leaves if too close.
 
MachiavellI420

MachiavellI420

Member
led's have a much better variety of all spectrums the sun emits naturally. on the other hand, i can buy a 1k watt hid setup for a fraction of the cost of a high wattage led light.
 
Cold$moke

Cold$moke

Well-Known Member
skeletor421 said:
I built my own high power led and found the opposite to be true
Click to expand...
Does your diy ligh produce asmuch as a 1k if so. Im interested

I enjoy tech and like mac said im using an mh with enhanced spectrum and with an old school 90w ufo

the black dog led vs hps video is pretty cool but the prices isnt

if its provens to outdo a 1k then the prices are worth it for long term energy savings but still

1800 for 1 light cough cough im think im choking lol
 
SupraSPL

SupraSPL

Well-Known Member
1K HPS produces about 350 PAR W but 70+% of the light is emitted in the wrong direction and has to be reflected into the canopy and in most case the photons have to go through a (dusty) glass shield. LED emits in a cone shape and if close to the canopy can be used without lenses or reflectors. So it takes less LED PAR W to get the same job done. On top of that, COB LEDs are now more efficient than large HPS bulbs (42-49% vs 35%) And all that is before we even consider the efficiency of the spectrum.

So to match a 1K HPS, you can use a lot less LED wattage to get the same job done. So to answer your question, yes LEDs can now easily put a lot more light into the canopy than 1K HPS and create a whole lot less heat as well. If you can put it together yourself, $600 can build a 500W LED that will match or out yield the 1K HPS. You can scale it down to as small as $60.

Vero 29 3000K $32
1.4A driver $13
CPU cooler $10
Fan power $6

10 of those would dissipate 510W in the COBs at 41% efficiency. So that is 210 PAR W of light compared to the 1KHPS which emits 350 PAR W of light. That should do the trick. Also, the HPS will create 650W of heat but the LED will only create 300W of heat. HUGE difference in practice especially if you scale that up for large grows.

For those planing on buiding a large lamp, they may consider large extruded heatsinks rather than CPU coolers.
 
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Cannasutraorganics

Cannasutraorganics

Well-Known Member
The latest studies show brightness of light to be the best growth. That's why led grows less rapidly. I want to build 300 watts of LED into a 1000 watt hps hood and use together.
 
skeletor421

skeletor421

Member
SupraSPL said:
If you can put it together yourself, $600 can build a 500W LED that will match or out yield the 1K HPS. .
Click to expand...
friend, I dont have any pictures of the 1x500w led chip I put together
(made it for a buddy), BUT anyone that wants to make one that strong BE CAREFUL YOU ARE WORKING WITH THE SUN!

I now work with 100w chips simply because its easier on the eyes
 
SupraSPL

SupraSPL

Well-Known Member
Cannasutraorganics said:
The latest studies show brightness of light to be the best growth. That's why led grows less rapidly. I want to build 300 watts of LED into a 1000 watt hps hood and use together.
Click to expand...
Using LEDs, we now have the ability to increase the intensity in the canopy way beyond that of a 1000 HPS (HPS = 16 PAR W/ft², LED up to 50 PAR W/ft²) if we wished, but it is not advised to do so. 50 PAR W /ft² would destroy any living plant material. It is easy to bleach the leaves, even with warm white. Also, photosynthetic efficiency decreases as you approach the maximum. We are better off to stay in the 600-1000 ppfd range and try to spread it on the canopy as evenly as possible. I use about 17 PAR W/ft² and am happy with that intensity.

If you are severely limited by space, it may be worth while to try and max out the intensity in the canopy to get maximum yield.
 
Sow to Grow

Sow to Grow

Well-Known Member
Cannasutraorganics said:
The latest studies show brightness of light to be the best growth. That's why led grows less rapidly. I want to build 300 watts of LED into a 1000 watt hps hood and use together.
Click to expand...
Can you direct me to these latest studies? I'd like to understand what you mean by brightness. One of observations that comes out of the graph I shared is this, "When PPFD is equal for two different spectrums, the LumiGrow LED spectrum has almost twice the rate of photosynthesis." The spectral distribution curve definitely affects growth, so that begs the question - what's the best spectrum for a particular plant at a particular stage that achieves our desired result? The answers will translate over to the market in the form of spectrum control and light programs.

Growers are gonna be able to use light like they use their nutes to change flavor, smell and chemical composition. Neat stuff!
 
WestDenverPioneer

WestDenverPioneer

Well-Known Member
I grew Gerberas for years, indoors, under HO flourescent lights. They don't have very high light requirements and I wouldn't compare them to cannabis in terms of growth or flowering.
Just because LEDs are kicking well with Gerberas does not mean you will have a hefty crop of Cannabis in the same fashion.
LEDs work great for veg. I've built my own LED units and did a test on plants that never saw any other type of light than LED. The veg growth was remarkable but for flowering it falls short. If you are doing a compact/stealth grow with small plants it could be a viable choice.



SupraSPL said:
1K HPS produces about 350 PAR W but 70+% of the light is emitted in the wrong direction and has to be reflected into the canopy and in most case the photons have to go through a (dusty) glass shield. LED emits in a cone shape and if close to the canopy can be used without lenses or reflectors. So it takes less LED PAR W to get the same job done..
Click to expand...
It doesn't take less PAR to get the job done. If dust will settle on a glass shield it will also settle on an LED as well as its reflector. Fans that drive heatsinks will slow down over time as they build up with dust.
 
Sow to Grow

Sow to Grow

Well-Known Member
WestDenverPioneer said:
Just because LEDs are kicking well with Gerberas does not mean you will have a hefty crop of Cannabis in the same fashion.
Click to expand...
You're right. The logic doesn't bear out, nor did I make that claim in my post. I was pointing out the difference in photosynthetic rate between an HPS spectrum and an LED spectrum. The same study applied to Cannabis would be very interesting. We're working on getting that study off the ground.

But I'll make a claim based on my experiences - commercial LED fixtures in the hands of experienced growers are as good or better for businesses producing cannabis flowers.

Check out JR's grow journal. He's using a stronger version of the fixtures used in the University of Guelph Gerbera study. Those colas are popping off the stalks.
 
Cold$moke

Cold$moke

Well-Known Member
SupraSPL said:
1K HPS produces about 350 PAR W but 70+% of the light is emitted in the wrong direction and has to be reflected into the canopy and in most case the photons have to go through a (dusty) glass shield. LED emits in a cone shape and if close to the canopy can be used without lenses or reflectors. So it takes less LED PAR W to get the same job done. On top of that, COB LEDs are now more efficient than large HPS bulbs (42-49% vs 35%) And all that is before we even consider the efficiency of the spectrum.

So to match a 1K HPS, you can use a lot less LED wattage to get the same job done. So to answer your question, yes LEDs can now easily put a lot more light into the canopy than 1K HPS and create a whole lot less heat as well. If you can put it together yourself, $600 can build a 500W LED that will match or out yield the 1K HPS. You can scale it down to as small as $60.

Vero 29 3000K $32
1.4A driver $13
CPU cooler $10
Fan power $6

10 of those would dissipate 510W in the COBs at 41% efficiency. So that is 210 PAR W of light compared to the 1KHPS which emits 350 PAR W of light. That should do the trick. Also, the HPS will create 650W of heat but the LED will only create 300W of heat. HUGE difference in practice especially if you scale that up for large grows.

For those planing on buiding a large lamp, they may consider large extruded heatsinks rather than CPU coolers.
Click to expand...
I get the par readings and all that

thats what sold me on the old led

but as long as theYIELDS is matched

I would happily change over to led

and I love to build anything
Being in commercial construction I sometimes have access to cool materials like lots of aluminum and steel wire ect
 
S

ScrappyD

Active Member
this may be a weird question but can you mix the two? Say a 400w HPS on top and 2 150w LED panels on the sides? And would the difference from the added LED panels be worth the price?
 
Sow to Grow

Sow to Grow

Well-Known Member
ScrappyD said:
this may be a weird question but can you mix the two? Say a 400w HPS on top and 2 150w LED panels on the sides? And would the difference from the added LED panels be worth the price?
Click to expand...
I've heard about people mixing fixtures and spectrums. MG has a video about the hybrid concept. And I think there are videos of people who have tried.

I guess some of the questions to ask are:
  1. At what point will the plants hit saturation of usable light the footprint of the proposed combo?
  2. How much are you willing to spend to test out the theory?
 
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