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lighting LED lighting

Lawrence

Lawrence

I have been reading a bit about this new technology for growers, but I am not sure if I am convinced yet. Since all of the reviews I can find are published by people selling them!
In theory it makes sense that LEDs can produce absolutely the correct bandwidth of light for plants. What I am unsure about is if the intensity is enough? They certainly are cheap to run, but do they work?
 
Lawrence said:
I have been reading a bit about this new technology for growers, but I am not sure if I am convinced yet. Since all of the reviews I can find are published by people selling them!
In theory it makes sense that LEDs can produce absolutely the correct bandwidth of light for plants. What I am unsure about is if the intensity is enough? They certainly are cheap to run, but do they work?
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I did some research on this a while back and although the lights "can" grow plants the plants will always grow better in plan old sun because LED's just don't give off enough intense light that the plants need to make a huge difference like HID lighting will. The key selling point is that they use less electricity and are suppose to last longer, but I have read quit a few complaints from users (some here) that the lights burn out in less than 6 months. Bottom line if you live in Alaska and are in the dark 24 hours a day and electricity is expensive I can see a reason for LED's. Outside of that I couldn't recommend using LED's for anything. If you want to grow a MONSTER plant in a few weeks just get some HID equipment and be done with it. Yes it will cost more to run, but you can get a 400 watt ballast and cheap hood for a couple hundred bucks and just pay the extra $20 a month to run it. If everything is done correctly in weeks you will be picking more fruit than you know what to do with.
 
hot stuff said:
With the HID how far do they have to be from the plants?
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Depends on the wattage! A 100-watt HID can be a lot closer than a 1000-watter!

Rule of thumb (or back of hand). Hold you hand, palm down, at the plant canopy. If you feel anything more than warm, the lights are too close.

Mike
 
I agree with Mike. I would also like to add that I believe it also depends on your hood. Mine has a glass lens as well as an exhaust opening. I have it hooked to a fan that runs while the light runs. It pulls fresh air across the bulb while exhausting the hot air. This past spring I had tomatoes touching the glass with no ill affect. It certainly isn't something I would encourage but am just saying... I also only have a 400 watt setup so obviously a 1000 watt setup is going to produce more heat.
 
millworkman said:
At least a couple feet, most HID's put out a lot of heat and can burn the tops of your plants.
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It is true that they put off a lot of heat, but I can put my 1000 watt hps less than 1' from my plants and not feel the heat. This is because I use a "cool tube" that is a completely sealed off glass tube attached to a small fan that removes 90% of the heat from the bulb. Again if you fail to plan you plan to fail so do your homework and you won't be sorry.

You should check out maximum yields website they have a ton of articles and information online and the magazine comes in digital format every month. That or read through some of my previous post. Their is a lot to learn and you don't take the time to read you may end up thinking the closer you put the light to your plant the more lumens your going to get ;)
 
Not an expert so just rambling... when you remove the heat of the HIDs completely and simply keep the temp constant wouldn``t this effect the blooming-setting fruit stage? No temp differential...
 
I think it's more the amount and color of the light more than the heat, though too much heat and too little heat can affect them.
 
LED technology is progressing quickly. If you buy now your lights may be obsolete in 1 year. They work. The question is if they can compete with the other options you have.

The advantage they have is that they can hit a specific frequency. The downside is that almost all have one two frequencies; rd and blue in a 8 to 1 ratio. The ratio seems to be optimal for most plants, like tomato and cannabis. But photosynthesis require two red and two blue frequencies rather than just one. These frequencies are very close to each other so the red LED and the blue LED hit them both. Also, you are mostly stuck with 8 to 1 red-blue ratio. I have seen some that add yellow or white, but I don't know what that does to the plants. I guess photosynthesis uses more than just those 4 main frequencies.

Another thing is that most seem to be no name Chinese LED panels. You can't even figure out the name of the manufacturer except in a few cases where the panels are made in the US or Europe. And in that case the product are 50% more expensive.

Intensity isn't the problem, it seems. The lights produce plenty of lumen and they need far less lumen for the same Photosynthetic Photon Flux Density.

But all these products still have 1 watt LEDs. I heard that the latest generation LEDs are 3 watt so all these already ought to be obsolete.


I decided to buy a 125w CFL. It gives good light but you can only put a couple of plants under them. It's not a 600w HID or a 120w LED. I didn't see the point in buying an expensive LED telling myself that it is a long term investment when I can't be sure of the quality and that each year a new and superior product is released.
 
5 watts are available... we have been using them to replace various lights in trains...

BUT, they are 3-4x as expensive as 3 watt!!!


Edit; check Luxeon or Cree for those.
 
Of course they exist. The point is grow lamps with 5 watt LEDs. The only lamps I have found with 3 watt LEDs are bulbs often with just 1 LED. All panels I have seen have 1 watt LEDs. Maybe the 1000-2000 euro ones have the newest generation 3 or 5 watt LEDs.
 
hot stuff said:
I think it's more the amount and color of the light more than the heat, though too much heat and too little heat can affect them.
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I do a lot of experimenting with lights of all types - CFL, HID and LED among them. IME, it is a combination of Daily Light Integral (DLI), Growing Degree Days (GDD) and the age of the plant.

DLI is a measurement of PAR light plants get per day. Tomatoes and Peppers need 18 moles minimum, with 21-22 recommended.

GDD relates to how plants and even insects react to an accumulation of temperature above a given standard (usually 50 or 52 degrees). An example is a typical 75 Days to Maturity tomato plant. Forty to Fifty days after being transplanted they will typically bloom if they get the 18 moles per day of DLI and the GDD is about 1300-1500. OTOH, even if they get the needed DLI but the GDD is too low, they do not bloom. And like a female, they have a given amount of time they are "fertile." If the above plant turns 90 days old before it reaches the 1300 GDD mark, most of its ability to produce a flower, and for that bloom to turn into a fruit, disappears.

As for LED lights - plants need all the spectra, not just a couple of red and blue ones. They don't absorb much of some of them, such as green but like humans, they cannot flourish on just one cut of beef and one type of greens alone - they need a balanced diet. What I find odd - LED billboards that can display at least 256 colors and change constantly are all over the place, but yet they have not made their way to grow lights.

Mike
 
Harunobu said:
Of course they exist. The point is grow lamps with 5 watt LEDs. The only lamps I have found with 3 watt LEDs are bulbs often with just 1 LED. All panels I have seen have 1 watt LEDs. Maybe the 1000-2000 euro ones have the newest generation 3 or 5 watt LEDs.
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My point was if you can`t get what you want then build it... that`s all :)
 
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