LED Light for Plants

[shpongled]

Hello, I have been without a electronics project for a while and have decided to build a small LED light unit to provide light for plant growth. The first unit I plan on building will be small, mostly for proof of concept and starting seedlings. Eventually I would like to scale up to something that might be able to keep a few small plants alive. Overall it going to be a cool project.

I am still working on the actual electronics design but have some knowledge and am getting help from the friendly folks at allaboutcircuits.com.

I come to you knowledgeable and hopefully friendly folks to help with my LED selection. I am hoping to use 1W LED's for their high output. The problem I am having sourcing parts with the right output wavelengths. It seems that many of the high output LED makers are focusing on the damn LED flashlight people :whistle:.

Here is a quick excerpt about the best wavelengths for photosynthesis:

Maximum chlorophyll A production occurs at 662nm (for red) and 430nm (for blue), while maximum chlorophyll B production occurs at 642nm (for red) and 453nm (for blue).

I find most commercial grow lights say they use 1W 660nm and 450nm LEDS. The issue is I cant find any? There are a few other ranges that are important but if anyone can help me with these it would be a big step.

I am going to use some cool and warm white lights also to fill out the gaps in the spectrum but there are a ton of options for those.

 

[shpongled]

Does anyone know anything about http://www.roithner-laser.com/LED_HP_single_chip.html

They seem to have many different LED's with 660nm output.

 

[joeparker54]

I understand the potential value of having separate sources for blue and red light - blue generally contributes to vegetative and seed growth while red light is important for flowering. However, I'd think that just for proof of concept, that simply finding the warmest and coolest cree (or any other brand for that matter) emitters you can would suffice. Of course it all depends on what you're growing, which could be anything from alfalfa sprouts to cannabis.

check out the graph on page 3 here. While not optimal, i'd say the levels of light in the ranges you require may at the very least be sufficient for 'proof of concept'

BTW, have you emailed any LED growlight manufacturers to ask what type emitters they use? It's worth a shot.

 

[Illum]

gee...I don't think any of those wavelengths exist in the literature of any high powered LEDs :thinking:

Maximum chlorophyll A production occurs at 662nm (for red) and 430nm (for blue), while maximum chlorophyll B production occurs at 642nm (for red) and 453nm (for blue).

Osram golden dragons blue only goes up to 470nm but with an optical efficiency of 6 lm/W

For Luxeons...

Luxeons Colors    Min    Typ    Max
Blue              460    470    490
Royal Blue        440    455    460
Red               620.5  625    645
Red Orange        612.5  617    620.5

For CREEs...
Dominant wavelength range

CREE Color    Min    Max
Royal Blue    450    465
Blue          465    485
Red           600    620

As far as I am aware of, 660nm +/- is only available in T1-3/4 variants, classed as "deep red." Blue 5mm LEDs are only in 470nm +/- variants only.

your better off looking for studio lighting filters and safelight filters to achieve those wavelengths. I'm pressed to believe that they've been limited because of too many irresponsible individuals growing cash crops in their basements

 

[Yoda4561]

But using filters defeats the purpose, maximum vegitative growth and minimum power usage.

 

[Illum]

But using filters defeats the purpose, maximum vegitative growth and minimum power usage.

well, its not like we have many choices:ohgeez:

 

[asdalton]

Filters can only exclude light, not create any more colored light than the light source already contains. There would be no point in using a filter.

 

[Illum]

so what do you suggest?

 

[znomit]

Filters can only exclude light, not create any more colored light than the light source already contains. There would be no point in using a filter.

The only reason a filter would be useful is if the other wavelengths degraded growth somehow.

Anyhooo, speaking of filters...
So how much of the sunlight do plants actually use? Would it be theoretically beneficial to convert sunlight to electricity and then power LEDs to grow the tomatoes?

 

[Ekke]

Here's Deep Red for you:
http://www.ledengin.com/led_products.htm
10W is better pricewise, if I remember right..

Plants may need many more wavelengths than just 450nm & 660nm (depends what plant and what you want it to do etc.), so you have been warned.. :)

 

[Ekke]

I find most commercial grow lights say they use 1W 660nm and 450nm LEDS. The issue is I cant find any?

It might be that they are just saying that they use 660nm leds.. And if specs are in lumens, it's pretty likely that they LEDs are ~620-630nm. Six times more lumens than 660nm for same radiant power.

 

[purduephotog]

Hello, I have been without a electronics project for a while and have decided to build a small LED light unit to provide light for plant growth. The first unit I plan on building will be small, mostly for proof of concept and starting seedlings. Eventually I would like to scale up to something that might be able to keep a few small plants alive. Overall it going to be a cool project.

I am still working on the actual electronics design but have some knowledge and am getting help from the friendly folks at allaboutcircuits.com.

I come to you knowledgeable and hopefully friendly folks to help with my LED selection. I am hoping to use 1W LED's for their high output. The problem I am having sourcing parts with the right output wavelengths. It seems that many of the high output LED makers are focusing on the damn LED flashlight people :whistle:.

Here is a quick excerpt about the best wavelengths for photosynthesis:


I find most commercial grow lights say they use 1W 660nm and 450nm LEDS. The issue is I cant find any? There are a few other ranges that are important but if anyone can help me with these it would be a big step.

I am going to use some cool and warm white lights also to fill out the gaps in the spectrum but there are a ton of options for those.

Ledengin Makes a 10W, 5W, and a 15w (I think) 660nm LED.

http://www.newark.com/ledengin/lz4-40r210/power-led/dp/16P3167

I own 5 of them.

 

[Ekke]

Ledengin Makes a 10W, 5W, and a 15w (I think) 660nm LED.

15W is quite useless (10W on the left, those are RED because there isn't 15W Deep Red datasheet), if you know how to successfully cool a LED.

 

[Illum]

I oftened wonder how well these 10W/20W/30Ws contend in efficiency. and I've wondered of the possibility of using a narrow copper pipe with flat planes on both sides and have water flowing through the middle. A medium sized sump pump and a 5 gallon reserve oughts cool a pipe the length of length the table with no issues. water has high heat capacity and the warm water can be used for other things, especially for sanitary wash/flushing

 

[kaichu dento]

My friend from University of Alaska Fairbanks is here in Japan right now for some conferences on lighting and last week he got a frantic message that our lettuce is just not growing since the sun went away and we've been running with nothing but 1,300 watts from LED's since August. Previous to the change we'd been giving the lettuce 18,000 watts from the Incans.

The big Incans are back on again and according to some of the Dutch growers we need to use a mixture of LED and Incan with the main point being lots of light, especially for the tomatoes.

 

[asdalton]

I'm surprised that they're using incandescent for growing, rather than the much more efficient metal halide or high pressure sodium.

 

[kaichu dento]

I'm surprised that they're using incandescent for growing, rather than the much more efficient metal halide or high pressure sodium.

Metal halide and high pressure sodium are the incandescent lights we're using, for a grand total of 36,000 watts between the tomatoes and lettuce, not to mention another 6,000 watts in the little greenhouse.

 

[asdalton]

Here on CPF, "incandescent" means tungsten filament. That was the source of my confusion.

 

[Illum]

Metal halide and high pressure sodium are the incandescent lights we're using, for a grand total of 36,000 watts between the tomatoes and lettuce, not to mention another 6,000 watts in the little greenhouse.

Metal halide is effective in output, but you'd be surprised for small scale applications how effective incandescent lamps are in keeping a greenhouse toasty warm when its practically frozen over outside.

Down here theres no weather of that sort for me to try it out myself:ohgeez:

 

[kaichu dento]

Here on CPF, "incandescent" means tungsten filament. That was the source of my confusion.

I may be the exception, but my usage of the term incandescent includes anything with a filament.

Metal halide is effective in output, but you'd be surprised for small scale applications how effective incandescent lamps are in keeping a greenhouse toasty warm when its practically frozen over outside.

Down here theres no weather of that sort for me to try it out myself:ohgeez:

We've been through five winters with the little greenhouse and three for the big one. For the last three winters (this is the start of our fourth) we've been pulling fresh lettuce and tomatoes out every day of the year, even at -60 below. It definitely makes a big difference having all those lights on!