# White -vs- blue LEDs for plant growth



## blasterman (Apr 30, 2012)

A few months ago I converted some of my DIY growth lights from XT-E royals to XP-Gs, mostly for aethestic sake. Royal Blue and Orange-Red might be good for plants, but 30watts of XT-E are obnoxious, even in another room with a monochromatic, radioactive purple glow that after awhile drives you nuts.

Even at a 2:1 red to cool-white ratio the improvement aethestically was quite substantial. The rosy orange light produced by 5000k XP-G's and 625nm red is actually quite pleasant and easily works in the corner of a living room or kitchen. I noticed no difference in growth in about a dozen different house plants. If anything, I think it accelerated, but it's been warmer in my living room as well. One thing I did notice was an improvement in plant coloration after switching to whites. I've noticed over the past couple years that when plants grow under intensity royals their leaves turn vivid green with a plastic or vinyl texture that almost feels fake. I keep a variety of house plants ranging from corn plants to philodendrons to any thing else I can pick up onsale, and I noticed that when I switched to whites the coloration returned back to plant leaves. 

I'm currently running 70watts total on my main light rig, which consists of about 40watts of red and 30watts of XP-G white. Anything within a 3x5' area under that light grows faster than next to a window, sometimes much faster# Some plants respond to the artifical light with rather astounding growth while others grow normal# I recently picked up some terrarium plants on sale, and the Fittonia pictured below doubled it's size in a little over a week under the LED's# I'm going to grab a tomato plant or two when the weather warms and see if the energy density is high enough for those# Another advantage of cool-white LED's is they are available up to pretty much unlimited power levels# Blues aren't#

In the long term though I'd really like to get a small coleus garden going indoors# Coleus varities have some pretty vivid and wild colorations, but they are fickle about growing indoors and are fussy about artifical lighting# If I can find the right combination of wavelengths to keep those happy it would be a pretty nifty way to have some color growing indoors other green, and likely only works under LED#


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## slebans (Apr 30, 2012)

Very healthy looking plants!

I think it was two years ago, my Nursery started selling a new annual variety of dwarf Coleus. The coloring was simply spectacular. I had more comments on that plant than anything else in my landscape - even plants costing hundreds of dollars more. I cannot think of the cultivar off the top of my head. I'll Email my Grower tomorrow and get the name for you.


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## blasterman (May 1, 2012)

I really don't have that good a green thumb, but pretty much everything grows well under the proper LED intensity. I bought some flats of generic coleus the other day, and am currently seeing how well they grow compared to the other flat going in a friends garden. I have a suspicion coleus is going to prefer a much bluer spectrum to keep it from growing 'leggy' and going to seed, but we'll see. If that's the case, I can park those under a panel of 10,000k LEDs, and the bluer light will certainly bring out some of the colors.

Coleus are certainly spectacular, and some of the newer varities have coloration that defies description. Most people consider them annuals though given they are so fussy going indoors in the fall. If mine do well, which I'll know in a few weeks, I'll set up their own section indoors with only the wilder color varities. I'll also pass on the spectrum mix to all the growers if it turns out to be a specific ratio.

Now we'll see how long it takes the Chinese light manufacturers to switch to white/red combos -vs- blue/red combos


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## slebans (May 1, 2012)

Our Grower got back to me and he thinks the cv I picked out was Henna.

I prefer White and Red LED mixtures simply because the output is more natural in comparison to Red and Blue. I find it much easier to determine the health of the plants under White and Red.


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## blasterman (May 1, 2012)

Coleus - Henna - found it. Yeah, that's neat.

Blue dominant lights make it pretty much impossible to see what you're doing or see detail in/on the plant. Cool-white...so much easier.


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## SemiMan (May 2, 2012)

One issue you may be having is the reds you are using ... and the mix of blue/red.

You really should be using 650-660nm red LEDs deep red LEDs. The wavelengths are better for photosynthesis not to mention the LEDS droop less with temperature and their radiometric output is actually a bit better than 630nm.

The other issue you inadvertently fixed is that you need to control the relationship between blue and red. It should not be consistent during the whole growing process.

Semiman


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## blasterman (May 2, 2012)

> You really should be using 650-660nm red LEDs deep red LEDs.



Sorry, but there's no evidence to that other than specialty flowering applications, and a while lot of propoganda from the dope growing industry, which I want nothing to do with. Talking to a web-site owner a few weeks ago that sells 660-670nm Chinese LED's he stated by his own estimates that 90% of their sales go to home dope growers. For the billionth time, ain't growing dope.

Along with the same arguement that high pressure sodium is the current preference for orange-red augmentation, and for the billionth time HPS does not emit much beyond 620nm. I've been running 620nm - 630nm orange red LED's over house plants for a couple years now, and the growth rates are startling. That little Fittonia doubled in size in a little over a week, and there's no far-red in my mix. Corn plants grow about twice as fast as they do when next to bay windows.

Even *if* far red worked as well as orange-red, the fact is that 620nm-630nm is perceptually much brighter to your eyes which alone is more appealing. I ran into the same issue with reef tanks when using 440nm LEDs -vs- standard royals. The 440's grew coral just as well, and actually we're less prone to bleach reactions, but the greater perceptual intensity of 450-455nm (royal) was much mroe appealing. So, the billiard ball physics of trying to align the chlorophyll absorption curves with LED spectra isn't exactly as simple as it sounds.

Spectral balance likely has more validity, but I can't align red-blue with every plant's preference, and in the wild plants don't typically choose which portion of the sun's spectrum they want other than producing pigments. Using whites -vs- blues will likely help as well in that department. So, I guess I'll continue to grow an increasing varity of plants while other indoor gardners continue to struggle with royal / far - red based Chinese lights that don't really produce much other than Woodstock flashbacks


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## SemiMan (May 3, 2012)

No evidence? How can you say there is no evidence when the absorption peak for photosynthesis (well one of them) is centred around 650-660? That is where the best energy efficiency lies and hence why it makes the most sense to have your red leds there.

This has nothing to do with "dope" growing, it has everything to do with simple energy efficiency. I am pretty certain that Osram and Philips Lumileds have not recently released deep red LED with a heavy emphasis on indoor farming purely to support dope growing. Likely also not the reason that GE, Philips, etc. are spending millions on LED grow light research and new 650-660 LEDs are a key part of that.

With the exception of some recent Epistar die (Epistar does not make LEDS), Osram and Philips Lumileds, high efficiency 650-660 has not even been available such that reasonable tests could be done to look at energy efficiency of growth.

I am not saying that 620-630 is not better than white alone, just that you are likely to achieve better energy efficiency versus growth at 650-660nm. 650-660nm LEDs have higher radiometric efficiency than 620-630 and they are also much less sensitive to droop with high temperature further increasing the application based radiometric efficiency.

Keep in mind HPS is used because it has much higher radiometric efficiency versus other traditional sources when it comes to stimulating certain forms of photosynthesis. The fact that there is nothing beyond 620 is a rather mute point. Compared to all other available light sources prior to the new high efficiency 650-660nm LEDs, it was the best at stimulating photosynthesis in the red. Now that there are other options, it will as LED price comes down fall by the wayside.

Semiman


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## ToyTank (May 4, 2012)

Well I guess I'll have to keep buying my weed on Craigslist

Seriously though nice thread I'll be watching. I'd like to supplement natural light with LEDs to get a longer growing season for my vegetable garden next year. I live in the north, bottom of a valley mountains on all sides.


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## eh4 (May 4, 2012)

yeah, interesting thread.
I'd like to be able to enhance sprouts and greens growth during the winter months using led light with very limited wattage, solar and thermo electric being the power supplies.


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## Drumwerx (Nov 16, 2012)

@blasterman I know this is an old thread but because it is related to a thread I started about leafy greens I wanted to find out how your plants were doing with the cool whites and reds.

I have been really researching all of this for awhile and ran across this thread and wanted to hear more on the results. 

I also will be posting some more on my other thread and need your input. I have read a lot on what you are doing and respect what you have to say.


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