I raised pepper seedlings under LED light, and they *loved* it. After my squash/melons, they grew the most under it. I'm now in the process of trying to raise one of them to fruiting under LED light (I just put the others in the ground today).

Penetration can be improved via reflection. That's my approach, at least.

MH and HPS are, at present, the most efficient light sources.

This may change as LED lamps evolve.......

MH and HPS are, at present, the most efficient light sources.

Absolutely not. Look, NASA doesn't use LEDs for the fun of it when it comes to growing plants in space. You know all that heat that MH and HPS put out? That's wasted power. A lot of it.

Blue and red LEDs not only have nearly three times the quantum efficiency of MH and HPS, but they're also the ideal spectrum for plants to convert light into energy. LEDs aren't great for room lighting because they're poor at producing green and near-green colors like yellow, which our eyes are most sensitive to; however, plants are least sensitive to green (they reflect most of it, which is why they look green), and are most sensitive to red and blue, which is what LEDs do best. *And*, MH and HPS ballasts often have low power factors. A low power factor doesn't mean you have to pay more for power, but it does mean that the grid has to generate more. Some ballasts have power factors in the 0.5 range; that means that the grid is having to generate *double* the power you're billed for to account for the ballasts throwing the AC out of sync. LEDs generally have power factors of over 90%.

Basically, to sum up, you're absolutely wrong.

Actually karen, he is not totally wrong. If by "efficient" he means power efficient, then yes he is wrong. But, the best growth is done under sunlight naturally, since they have evolved under it. Since plants evolved under sunlight, they adapted to certain spectrums other than just red and blue, what LEDs emit (very little of actually). For this reason HID lights (Metal Halide/HPS) are much more efficient for plant growth. For one to get as good results as HID lights with LEDs, they would have to have a very extensive LED setup.

Sorry i did not explain more in my last post, i was in class and the bell rang (Yes, i am still in high school...). But as in my last post it sounded like i was saying LEDs do not produce enough red and blue spectrum, it is actually the total opposite. The lack of other spectrums present in red/blue LEDs result in not as strong, mighty growth, but more of a leggier/lankier plant. The one other problem that LEDs have when growing plants is the lack of light penetration. Have you ever put LED grow lights under a grow light meter? The penetration is extremely low. I actually have what a website said to be an amazing LED setup, being used as supplementary light to my 400w MH/HPS lamp. I gotta say, they really do make a difference as supplemental light, but as the main source of light will not produce results as good as HIDs.

That's not true, either. Doing a random google image search, here's what someone's MH peppers look like after 27 days (left hand row):

Here's what my LED peppers looked like after 29 days -- and note that these peppers were not directly under the light:

{{gwi:1005694}}

Whose look bigger? Oh, and on the right of their photo, see their pattypan squash (next to the beans... note that I didn't grow any beans, so I don't have a comparison)? Well, here's my pumpkin (on the far side of the chamber) at day 32:

{{gwi:1005696}}

Does that look "leggy/lanky" to you? I mean, it was freaking blooming there -- see any blooms on their pattypan? It was photosynthesizing so fast that it was burning through the water in that pot every two days (a similar sized pot with only tiny plants would take 1-2 weeks in the low-heat environment of the LED light); it actually caught me offguard at one point, and I lost some leaves because I wasn't watering it often enough. I also had a Ronde de Nice zucchini bloom in there shortly afterwards. All of these plants are now outside and transplanted excellently.

As stated earlier, penetration is solved via reflection.

Again, NASA doesn't use LEDs for the fun of it. Plants absolutely, positively do *not* need full spectrum to grow properly. That's like saying that humans need to eat every element in order to be healthy -- not only are many elements not useful, but some are outright harmful. Most of that "full spectrum" is wasted/used inefficiently, and some is even damaging (UV, for obvious reasons; deep red and near-IR also, as they just waste water and cause undesirable hormonal effects without contributing to growth. Even yellow can cause negative effects in some plants.). I got this growth out of a 90W UFO in a 2'x8' reflector chamber -- how many watts are you burning on your MH/HPS? 400, you say? I could have 4 1/2 times as many UFOs running for that much billed power -- and assuming a 0.5 power factor, 8 times as many for the amount of generated power. And you're going to claim that somehow MHs are more "efficient"? Come on.

Have you ever put LED grow lights under a grow light meter?

Grow light meters generally measure light in foot-candles -- and if you knew anything about PUR, you'd know that the candela/lumen scale is based on the sensitivity of the human eye, which is precisely the opposite as the sensitivity of photosynthesis. Here's the luminosity curve, used to measure lumens and candela:

The photosynthesis curve varies from plant to plant (and also by how you measure it), but is in general just the opposite -- peaks at red and blue and is lowest at green.

Update: I just found some more 1-month MH pepper pictures:

Hi karenrei,
I am also following you LED adventure over on Growing Under Lights forum.
? Have you concluded that the "UFO" light arrangement is the better option vs. blue/red Xmas LED's ?
You seem to have made a distinction on what does better with which lighting. A conclusion that leafy vegetables, like lettuce, are less suited to blue/red LEDs appears counter-intuitive.

The UFO does better than the Xmas lights. The Xmas lights weren't able to sustain lettuce without it going leggy. The UFO was, except on one far edge of the chamber, 3-4 feet away from the light. Same with brassicas. Peppers, tomatoes, eggplant, squash, and melons did fine in every position in the chamber.

If only i had a picture of when my peppers were under my MH :(

Many of you're points are what most of the LED propaganda out there has to say. Also, NASA only EXPERIMENTED with them because of the low power usage, not because they are the best lights to grow plants with.
Four and a half UFOs? I could get better results running a 600w MH/HPS for a whole year, and even including my billing price for it, it would not even come close to the price of 4/5 UFOs. Also, the light meter i am talking about is measuring the penetration of the light, i was not talking about measuring foot candles, some meters have many other measurements besides foot candles to choose from. Are you sure those peppers are one month under the MH? Jesus those are tiny.

And this may not be accurate as i do not know the specific strain the peppers under the MH, but the peppers under your LEDs are indeed a wee bit lanky (not very lanky, but much lankier than the ones under the MH).

I have used both, seen both results (more than once) and HIDs/Fluorescents grow better plants. LEDs are GREAT supplemental lights for HIDs/Fluorescents and i would highly recommend it.

Members of the nightshade family need some orange light for certain phytochemical processes. MH is a poor choice, HPS would have worked much better. Red-dominant LED arrays work great as well.

As a side note, T5HO lamps are great. They even make primary-color (red and blue only) T5HO lamps, so you can do an LED-like grow. They cover a little more of red and blue (not as targeted and narrow like LED, but as noted the PAR/PUR curve shifts depending upon plant cultivar, so a wider range helps make a better general-purpose light,) but they waste practically nil energy producing green or yellow light.

UV in tiny doses is great for most nightshades related to tomatoes and peppers. It encourages more aromatic oil production and leads to greater flavor.

Many of you're points are what most of the LED propaganda out there has to say

In your world, peer reviewed research is "LED Propaganda".

Also, NASA only EXPERIMENTED with them because of the low power usage

Amount of growth per unit power is otherwise known as efficiency.

Name a single NASA flight experiment that's used HID.

Four and a half UFOs? I could get better results running a 600w MH/HPS for a whole year

Wrong. 4 1/2 UFOs is what you're billed for a *400W* MH. 8 UFOs is what could be supported by the grid for every one 400W MH with a 0.5PF. If you want to go up to 600W, that's fine, but then the UFO count goes up to ~7 and 12 UFOs, respectively.

and even including my billing price for it, it would not even come close to the price of 4/5 UFOs.

Oh, you want to talk TCO? UFOs are available for Buy It Now on Ebay for $225. Your average bidding on one ends at about $175. If you watch carefully, you can get them for $140 or so. But let's go with $180. Let's just pretend that your ballast and bulbs and fixture for your HID setup is 100% free. That's nonsense, of course, but hey. You said, what, 600W? 0.6kW * 24h/day / 0.95 (let's say a very high efficiency electronic ballast just to keep favoring HID all the more) * 365.24 days/year * $0.10/kWh ~= $550 per year. That ideal HID setup is burning enough money worth of power per year to buy three UFOs per year.

The cost for a real grow operation is not in capital costs. It's in power costs. And LEDs use a tiny fraction as much power per unit growth, period.

Also, the light meter i am talking about is measuring the penetration of the light, i was not talking about measuring foot candles, some meters have many other measurements besides foot candles to choose from.

And you were measuring PUR, right? The proper measurement, right? I bet dollars to doughnuts you weren't. And what sort of reflector setup were you using? I use a fully enclosed reflector chamber.

Are you sure those peppers are one month under the MH? Jesus those are tiny.

Which peppers? I posted three pics. The first and third pics were the first two I found searching for "peppers", "1 month", and "HID", if I recall the search terms correctly, and all were labeled as such on their respective web pages. The second pic (the pinkish one) is my one-month peppers under LEDs.

And this may not be accurate as i do not know the specific strain the peppers under the MH, but the peppers under your LEDs are indeed a wee bit lanky (not very lanky, but much lankier than the ones under the MH).

Oh come on, those peppers are healthy as a horse, and way bigger than the MH peppers that I found in a quick google search. And they're not even directly under the light. The light was about two feet above the ground, pointing down, and these peppers were about two to three feet to the right of it.

I have used both, seen both results (more than once) and HIDs/Fluorescents grow better plants.

And my experience is opposite yours. And I'm betting it has to do with your setup. And this is with a mere 90W, at probably nearly twice the power factor of your lights.

what needs to be done with respect to LEDs is a common means of evaluating light received by the plants needs to be developed.
Though many different scales are used in light meters, they do in fact all (at least the common ones) measure the same spectrum of light. this, as karenrei pointed out, is not the spectrum that LEDS work most efficiently at. you can not use a light meter on LEDS and get any reasonable comparison to traditional lighting.
I personally applaud her (assumption here with karen in your S/N) efforts. I am interested in LEDS but without some means to judge how much of what is needed, we need folkz to actually run LEDS through the hole plant cycle to develop such standards.
I have noticed in karenrei's posts, she mentioned two times having moved plants outside at some point. Why? It leads the mind to speculate that maybe they don't produce enough photosynthetic power for larger plants. the lack of explanation leaves a lot to be desired (note: I am not saying anything negative about your experiment, just that lack of data can lead to misunderstandings) but maybe your experiment is really about plant propagation and early life cycle growth.
I still find in fascinating and am glad you're doing it.
Ps: one other note; NASA, at least in space, most likely uses natural lighting for there plants. I can't imagine there an artificial light out there better than opening the blinds.

I have noticed in karenrei's posts, she mentioned two times having moved plants outside at some point.

FYI: I moved my plants outside because they overgrew my grow chamber. I was using the grow chamber to start plants for my garden.

I agree that I could probably do a better job with the experiment. I'm quite welcome to ideas for new experiments, if anyone has any ideas. Summer is the ideal time to experiment, as my chambers aren't crowded with winter seedlings. I'm doing my first fruiting test right now -- I put one of my peppers and eggplants back in the chamber (I had been planning to plant them all, but someone recommended otherwise), and I'll report on how they do. I picked the least healthy of each type of plant -- the eggplant was one of my smallest and the pepper had become somewhat limp from its brief exposure to the cold (it's perked back up already).

Ps: one other note; NASA, at least in space, most likely uses natural lighting for there plants. I can't imagine there an artificial light out there better than opening the blinds.

NASA experiments are generally self-contained little boxes that get shipped up in cargo and do most or all of the process by themselves. It'd cost way too much and be way too much effort and weight to try to rig it to the viewports (or even worse, outside) -- and light in orbit is kind of funky anyway (rapid day/night cycle, no atmospheric radiation filtering, etc). Even plant experiments not designed by NASA themselves essentially always use LED light -- for example, the famous microgravity dwarf wheat experiments on Mir:

I don't believe a plant could survive direct solar exposure outside of our atmosphere.

I want to see LED ideas applied to other lighting technologies.

I particularly liked the post where a random picture from a google search was used as "proof" that seedlings grow faster under LED than MH.

We don't know how long those seedlings were actually growing. We don't know when the "clock" was started (planting? germination? first appearance of seedling?). We don't know what the humidity, temperature, or any other relevant factor in the growth of those plants.

To point to that picture and then to another picture of completely different plants grown under completely different conditions and say "aha! proof!" is absolutely ridiculous.

Nutrition alone could account for a far larger difference in growth. As could genetics - there's nothing to suggest the plants are even from the same strain.

And the "NASA uses it" argument. That's rich. NASA is researching methods to grow plants in space. I don't want to grow plants in space. The ISS may make enough electricity to power 42 homes but I'm guessing they've still got a pretty tight budget for grow light power - not to mention heat. The average terrestrial grower has less issue dissipating waste heat and therefore can afford to make more of it if that means easier access to more light.

Just look at the guys growing the naughty plants. There aren't any big grows under LED power and it sure as hell isn't cause those guys can't afford the lights. If anything the reduced electrical demands and heat output would be a boon to them. They don't use LED's for anything more than supplemental side lighting simply because the HID lights do a better job in every possible category of actual plant performance.

But simply put, NASA's priorities don't jive with what 99% of the hobbyists out there are trying to do. I could care less about low-G plant growth. I'm not worried about how to dissipate waste heat into the near-vacuum of orbital space.

Besides, NASA considers LED's to be low-tech now anyway. They're playing with "brighter than the sun" toys now. I forget what they're called.

I particularly liked the post where a random picture from a google search was used as "proof" that seedlings grow faster under LED than MH.

You have a better comparison point?

I didn't think so. I pulled up two google pics of peppers whose owners labeled them at about a month and as having been grown under HID. Don't like it? Then you do better. I can't magically conjure up perfect arbitrary comparison photos to meet your whims.

but I'm guessing they've still got a pretty tight budget for grow light power

Gee, you think? They need to conserve power, you don't say? To get as much growth as possible from as few watts as possible? And NASA chose LEDs for that role? Hmm, I wonder what that means....

Just look at the guys growing the naughty plants. There aren't any big grows under LED power

Oh come on -- a good chunk of the UFO auctions on Ebay specify things like "minimum heat signature" or "comes in plain brown box for privacy" or things of that nature. You think it's people growing lettuce that are worried about heat signatures or people knowing that they're buying grow lights?

Besides, NASA considers LED's to be low-tech now anyway. They're playing with "brighter than the sun" toys now. I forget what they're called.

Sulfur lamps, and no -- NASA is using both of them, but has so far only used sulfur lamps in ground experiments. Sulfur lamps have lower PUR but higher luminous efficiency. But, most importantly, they're an incredibly dense light source. A single small, lightweight bulb can light up a mall.

Karenrei,
could you post links to some research that validates the value of LEDs? and not produced by the LED guys either. I believe its called peer reviewed.
Thanks.

Sure. How about this one? If you want to skip to the results, jump p. 35, Sec. 4.1.3 and 4.1.4, then p. 40, Sec 4.2.2, 4.2.3, and 4.2.4. You may also be interested in "Concluding remarks and future aspects", p.49.

I do take issue with their cost analysis. They're using rather inefficient LEDs that are passively cooled, not actively cooled (hence shorter lifespans and even less efficiency), and their prices (from early 2008) are already well out of date because LED prices have been falling so quickly while the efficiencies have been improving. Also, their numbers are for large installations, which benefits HID more (ballast costs don't scale linearly with output, while LED output scales near linearly). Lastly their environmental summary doesn't even mention the power factor issue, which biases that comparison even more in favor of LEDs. Even despite all that, their environmental results still strongly favor LEDs.

One of the more interesting conclusions of the study, IMHO, was that lettuce grown under LEDs has improved nutritional quality than under lights designed specifically for plant growth.

cool. thanks.
In checking out the pot sites, I've seen a lot of the same conclusions.
I don't care for that stuff anymore, but I've found some, much more useful information on their sites. The reality is potheads had a big head start in hydroponic culture versus vegetable growers. They've been doing it for years, they run several life cycles a year, and they're more than willing to share the knowledge with each other in hopes to promote their cause. It's just a shame they don't have sections on their forums for growing ordinary (or legal, at least) plants.

You have a better comparison point?

No, but I'm not trying to prove any point beyond the point that you're not successfully proving a point.

I can't magically conjure up perfect arbitrary comparison photos to meet your whims.

No, but we've established that you can invent them to meet yours.

They need to conserve power, you don't say? To get as much growth as possible from as few watts as possible? And NASA chose LEDs for that role? Hmm, I wonder what that means....

That means that if you're trying to grow plants in space you should TOTALLY follow NASA's example. If you're not, then no, they don't automatically use the best method.

Say you want to read a book in the woods. Do you bring a 110VAC table lamp or a flashlight? Change the goal to reading a book in your home - which is the better choice there?

Total power use isn't completely unimportant on terra firma, but it's not the overwhelming concern it is when you're absolutely dependent on solar panels and batteries the way you are in space.

Oh come on -- a good chunk of the UFO auctions on Ebay specify things like "minimum heat signature" or "comes in plain brown box for privacy" or things of that nature. You think it's people growing lettuce that are worried about heat signatures or people knowing that they're buying grow lights?

Do you believe that everything sold is automatically the best product for the job?

Yes, people growing weed sometimes buy UFOs. You know what happens next? Those people very quickly go back to the HPS light they thought it would replace.

The people growing weed are - like grizzman said - way ahead of the curve on this. They don't grow with LEDs. Just because there's a product using LEDs targeted to them doesn't make that the best choice. If it was, they'd be using nothing else.

But in actuality they consider LED lights a novelty. HPS is the end-all-be-all of growing according to every pot grower.

Karenrei:

It's important to point out here that the inability to disprove is not the same as proof.

It's important to point out here that the inability to disprove is not the same as proof.

Why is the standard for the side claiming LEDs are better "proof" and the standard for the site claiming HID is better "inability to disprove"?

And how about the scientific research I posted above? Is that not good enough? I can cite a dozen more where that came from. Full spectrum is absolutely not a requirement. And in some cases, it's outright detrimental (such as yellow's hindrance of lettuce growth)

Total power use isn't completely unimportant on terra firma, but it's not the overwhelming concern it is when you're absolutely dependent on solar panels and batteries the way you are in space.

1) The argument was made that growing under HID was more *efficient*. That's simply wrong, and since efficiency is exactly what NASA needs and has extensively researched, their use of it demonstrates the point.

2) Power costs *are* the big cost for a home grow operation. Do I need to repeat the above calculations again? A 600W MH on 24/0 with $0.10/kWh power burns through enough power to buy *three* UFOs *per year*.

Do you believe that everything sold is automatically the best product for the job?

Once again, you're making a claim, I counter that claim, and then you're changing the subject. You made the claim that pot growers aren't using LED. I countered by showing that the sellers on EBay seem to recognize that pot growers are their primary market. And then you change the subject, as though the question was whether LEDs are the best product to grow pot. That's not what was being discussed; what was being discussed was whether or not they're being used, and that's the prime area where they're being used. But if you want *that* question answered, see the bottom of this post.

You know what happens next? Those people very quickly go back to the HPS light they thought it would replace.

I'd point to random cases on a google search that readily counter that assertion, but judging from your past history, you wouldn't accept that. So how do you expect me to counter that claim -- want me to hire a polling agency to prove you wrong?

They don't grow with LEDs.

They're the prime buyers of LED grow systems.

HPS is the end-all-be-all of growing according to every pot grower.

Ooh, you used the word "every"! Now *that* I can counter with a google search ;) First hit.

That's usually what happens whenever anyone mentions LEDs on one of those pot-growing forums (I have to agree with grizzman -- those are some folk who really know what they're doing). A small argument breaks out, between the folks who insist that it's worthless and those who insist that it's great. But there are usually more people on the "great" side. And this is for pot, a plant with a very dense canopy.

Seriously, what's the real complaint here? That a 90W UFO is really more the equivalent of ~200W-ish of HID than a 400W HID? Well, to quote Garfield, big fat hairy deal. They still give an amazing amount of growth per unit power, and that unit power is where the real costs in indoor growing are. And you don't have to deal with ballasts, heat, or burned-out bulbs.

FYI: I just won a second UFO for $125 (incl. shipping). Yeay!

Karen, from my perspective the research PDF link you posted helped you win the argument hands down provided you cater the type of LEDs to the plant you're growing.

From the abstract: "The results of the growth tests showed that the usage of SSL [solid state lighting - IOW, LEDs] in plant growth offers an unprecedented possibility to optimise the morphogenesis, the photosynthesis and the nutritional quality of crops. This can be done by controlling the quantity and the spectral composition of the radiation provided, areas where LED-based luminaires excel."

Regarding spindliness: "The smaller hypocotyl sizes, higher number of leaves and larger leaf areas of plants grown under LED1 and LED2 treatments in comparison to control plants resulted in more compact foliages and improved morphology."

The paper states that "Growth tests T1 and T2 showed that the bi-spectral component light provided by red-orange and blue LEDs is at least equally effective for biomass accumulation in lettuce plants as high-pressure sodium lamps." - and that answers the questions that I had anyhow.

Other relevant quotes from the paper:
"The utilization of yellow with red-orange and blue spectral components provided by LEDs showed a higher fresh weight, dry weight and leafexpansion rate and the highest number of leaves while maintaining a balanced morphogenesis in the growth test T1."

"HPS-grown plants in comparison with LED-grown plants were delicate and spindly in result of the larger leaf areas, longer hypocotyls and longer leaf lengths."

"Lettuce plants grown under LEDs in phytotron conditions showed sturdier growth indicating improved nutritional quality in terms of carbohydrates and lower nitrate contents than plants grown under specially developed fluorescent lamps for plant growth. The high nutritional value, low contents of nitrates and improved morphogenesis of LED grown crops are promising indicators, which may respond to the demand for high-quality products by consumers."

"The energy efficiency potential offered by LED technology may further reduce the economic and environment burden due to lighting and increase yields, resulting in improved production efficiency."

Comparing plants grown under LEDs with those grown under "special fluorescent lamps spectrally tailored for plant growth": "in spite of the special fluorescent lamp used, the sturdiest growth was obtained under red and blue LED treatment"

Their concluding sentence: "The utilization of LEDs may contribute to the improvement of production efficiency and it will also have its effects on the preservation of the natural environment. However, further studies have to be performed in order to clearly verify and quantify the benefits attained on the preservation of nature by producing quality vegetables and ornamental plants locally and year-round."

I think LEDs are not only a viable option for growing plants, but since you can apparently tweak the spectrum depending on your plant needs, their more efficient use of energy, the resulting decrease in CO2 emissions, and the higher nutritional content of the plants will result in future growers looking back on the use of HPS and MH lamps in the same way we look now look at CRT computer screens.

Here is a link that might be useful: USAGE AND CONTROL OF SOLID-STATE LIGHTING FOR PLANT GROWTH

Oh, and for what it matters, my indoor pepper plant is fruiting now. Although it was set back by a pest infestation -- some sort of white bug (not fungus gnats) in the soil eating the roots (and then somehow -- beats me how it got indoors all the way to my grow room -- a tiny caterpillar in the leaves.) I had to pyrethrin the soil and hand-pick the caterpillar. So my plant lost its lower leaves, and it has a couple minor holes in its upper canopy. But given how fast it was growing before that, I imagine it'll be just fine.

My indoor eggplant is still beautiful, and is about to flower. I'm so used to my outdoor eggplants which get all bugridden and stunted, so I'm impressed by how lovely plants they can be when that doesn't happen.

My rooting experiments have been mixed, but mostly successful. My okra is well rooted and is about to flower; it's doing better than the outdoor okra plant that *wasn't* chopped down by a cutworm! My corn that got cutwormed and my muskmelon that was brought in almost dead after wind damage, however, never put out roots; I don't know why. My geraniums and rubber trees seem to be doing fine, although I haven't yet seen the kind of growth that would make me feel comfortable taking either of them out of the rooting bath (both have their humidity bags off, however). I started rooting some tomatoes recently, but that's a nothing task -- tomatoes root if you look at them funny ;)

First, I agree with hooked_on_ponics. Especially on the goals issue.

Second, NASA is a good source for horticulture? They denied global warming for years despite real scientific data to appease neo con politicians and you expect us to find them reliable? They screw up so much compared to private companies and only still exist because of the legal issues holding private companies back. If they weren't government, they wouldn't still be around. Their success rate is seriously lacking. That is one reason why there is the ongoing debate for shutting them down.

Third, the experiment was on plants that grow well in partial sunlight!!! Radishes? You can grow radishes longer by shading them from sunlight under peppers or tomatoes. That should show you right there that they don't have the same needs. It would ONLY be applicable if it were on a plant that came close to the needs of peppers. Something that required more light penetration for example (as the teenager pointed out) or had as large of leaf surface area. Or a fruiting crop rather than a root crop. The Helsinki study isn't even relevant to the thread or the argument. So, you said you can cite a dozen more. . . let's have it. Seriously. I really am interested in LED tech and these studies seem a little hard for me to find.

Fourth, I don't deny the possibility that LED could or does provide better lighting. I don't know. I do know that someone who becomes hostile when their opinion is questioned proves themselves to be a very biased source of info and it is best to get your info elsewhere. They tend to associate their opinions, no matter how supported or unsupported, as extensions of themselves and when you challenge the opinion you are challenging them personally. That leaves no room for objectivity and arguing with them is useless.

As a beginner, original poster, then you may want to go with the tried and true. Experiments are for after you have a baseline of experience for comparison or for those with lots of money and room. Or just wait until more research proves or disproves the value of these LED's.

They denied global warming for years despite real scientific data to appease neo con politicians and you expect us to find them reliable?

If you recall, it was the NASA scientists who came forward with the allegations that the government was trying to force them to soften their (harsh) conclusions about AGW. One of the fiercest proponents of AGW on the international stage is James Hansen, the head of NASA Goddard Institute for Space Studies.

They screw up so much compared to private companies and only still exist because of the legal issues holding private companies back.

What "legal issues" are preventing private industry from building their own orbital spacecraft? None, that's what. Quite to the contrary, NASA holds their hand and tries to baby them along -- with funding -- to help them get into orbit, and they still have trouble making it. Look at the COTS program.

Third, the experiment was on plants that grow well in partial sunlight!!!

Which experiment? I've linked to about a dozen, covering lettuce, peppers, radishes, tomatoes, and all sorts of other crops. The most famous space LED growth experiments were on dwarf wheat. But while we're on the subject of radishes -- since when are radishes not full-sun crops? Bulb size in radishes is dependent on how much sun they get. They'll survive in shade but won't put on much bulb mass. People put shade cloth over them in the summer to stop them from bolting.

By the way -- notice all of those exclamation points... and then the poster actually has the gall to say, "I do know that someone who becomes hostile when their opinion is questioned proves themselves to be a very biased source of info"? I found that rather funny.

The Helsinki study isn't even relevant to the thread or the argument

A detailed study on LED growth isn't relevant to the subject of LED growth? Now you're just going off the deep end there. Or did you simply skim the header and decide that the paper only covers radishes? It also cites studies on lettuce, spinach, peppers, clover, onions, cucumber, and tomato, and they experiment on both lettuce and radish.

You'd do better to actually read research before you argue about it.

If you have a problem with peer review, just state as much.

Wow, you really are twisted. Since you throw the COTS program out there, take a look at it yourself. It is the government exercising control and shifting the technological innovation to the private companies. Duh. Why? Because NASA couldn't cut it and now admits the private sector can do better if properly funded (that little legal issue I mentioned is the basis for COTS). So they now have to hand over some control to commercial entities that have proven superior in tech advances, but COTS is in place so that the government maintains some control without the responsibility of the brainpower.

Which experiment am I referring to? The one you linked and I specifically mentioned as the Helsinki study. You are obviously highly delusional if you see above where you linked over a dozen of anything. You link one. The Helsinki one. The one on dwarf wheat wasn't about LED's at all. Maybe YOU should read the research. . . Straight from the link you provided: "The purpose of the experiment was to study the effects of microgravity on the reproductive physiology of higher plants." Where is there a mention of it being about lighting?

Are you a pro linker or a gardener. Many experienced gardeners that grows radishes knows you can grow radishes just as I said. They turn out sweeter and less spicy. The partial shade still allows enough light in for the radishes to accomplish photosynthesis. Growing in the shade of other plants makes it possible to extend the season. Oh, and guess what? Lettuce is commonly grown the same way to extend it's season beyond late spring or to get an early start in late summer. So yippee, the study covered lettuce, too. Still irrelevant to this thread. Just so you know, my radishes (under the protection of peppers) have nice bulbs to them. Links don't hold a candle to reality, Karen. I can't eat fresh links in the heat of summer, but I can my radishes.

You want to rethink your statement about the topic of the thread? It's about peppers that get 4+ feet and conditions for them. Read the original post. A study done on radishes or lettuces will not answer this post. If you think 4+ foot pepper plants are comparable to lettuce and radish or even to wheat then you need to do a little more research on plants instead of trying to pretend all plants are equal and thrive under the same conditions.

As far as your "peer review". . . What, because it was posted by you that a university I have never heard of had a student that submitted a dissertation TO THE ELECTRONICS DEPARTMENT I should accept it as gospel? I mean, seriously. Do you expect us to follow every one of those sources the guy cites? If the science is so definitive, surely you could find a study from somewhere that we've heard of. Peer reviewed doesn't mean the results are fact. It means the study was done properly according to colleagues known to be experts in the same field. And in this case, it was electronics. Not horticulture. It has nothing to do with verifying results, either. I don't have a problem with peer review. I just understand what it means. Apparently you misunderstand it to mean "fact" or even "verified results".

As far as you commenting on exclamation points. Yep. I exclaimed. Didn't belittle, though I am now since you make yourself hard to resist. Of course, you missed the point. I didn't belittle because my opinion is challenged. You did. Exclamation points aren't indicative of hostility. They are exclamatory. Get a dictionary lady. Or I'm sure you can link one. Of course, you will interpret it to mean whatever you want or you will just settle on one definition that suits your argument, right? You set the mood for hostility here first with Willard and then with Jeremy. Neither of whom were hostile toward you. Then hooked_on_ponics appears to have felt the need to give you a taste of your own rude medicine. And rightly so. From there, you hijacked this thread and even you admit it became about LED's rather than about "My hot pepper situation" that simply mentions LED's. Unfortunately, some of us got sucked in by you. Sorry original poster.

Wow, you really are twisted. Since you throw the COTS program out there, take a look at it yourself. It is the government exercising control and shifting the technological innovation to the private companies. Duh. Why? Because NASA couldn't cut it and now admits the private sector can do better if properly funded

I see you've abandoned your line of argument that there are some sort of relevant "legal barriers" preventing private companies from launching their own spacecraft. Quite to the contrary, they've been trying since the inception of modern rocketry; their failures litter the landscape. Getting out of this gravity well is just incredibly difficult.

Secondly, "the government" did not create COTS. COTS was the creation of NASA administrator Michael Griffin. Its origins date back to a 1990 *internal* NASA study called "Alt Access". And it's not because NASA "couldn't cut it". The whole point is to prop up private industry despite the fact that it has repeatedly not been able to "cut it", because if they can succeed in getting private craft to orbit, part of the development costs will be subsidized by the marketplace. I.e., NASA gets access for cheaper.

But really, why are you dragging this conversation to this complete tangent? A silly attempt to try to discount NASA research via guilt-by-association? So what, on all of NASA's peer-reviewed papers, did they pay off the reviewers, too? How deep does this evil NASA conspiracy to promote LEDs go?

You are obviously highly delusional if you see above where you linked over a dozen of anything. You link one

I linked to a study showing the negative effects of yellow light on lettuce, the microgravity dwarf wheat experiments, and there are a ton of studies covered in the Helsinki paper which I didn't feel the need to re-link on my own but were mentioned in one of my links.

Straight from the link you provided: "The purpose of the experiment was to study the effects of microgravity on the reproductive physiology of higher plants." Where is there a mention of it being about lighting?

Just two lines later: "This research was designed to further evaluate the technology used to support food production by crews on long duration space flights"

Is this Gardenweb School for the Blind or something?

Many experienced gardeners that grows radishes knows you can grow radishes just as I said.

Give me a break. Search for "sun" and "radish". Radishes grow optimally under two key conditions: cool and very sunny. Too hot and they bolt. Too little sun and they don't put on bulb mass. These are facts.

Just so you know, my radishes (under the protection of peppers) have nice bulbs to them.

You're still growing radishes in June? Mine are all full sized and out of the ground by May. You know, you might want to consider giving them more sunlight if you want to grow them faster. ;) Or is *your* goal to grow crops slowly? Well, if that's your standard, then by all means, my LED grow room is an abject failure! ;)

So yippee, the study covered lettuce, too.

Good to see that discovering your mistakes makes you happy. Judging from this thread, you'll probably live a very happy life.

Lettuce is commonly grown the same way to extend it's season beyond late spring

Like radishes, lettuce gets shaded to *slow it down* in the summer heat to stop it from bolting. This is really basic gardening here.

or even to wheat

Ha! That's really funny. Close-packed wheat pretty much defines a dense canopy. Peppers can't hold a candle to grains in terms of shading. Peppers even have a pretty spare canopy compared to lettuce and radishes. Come to think of it... I'm having trouble coming up with garden crops that have a *less* dense canopy than peppers generally do. Tomatoes? Nope. Eggplant? Maybe, but not usually. Mint? Nope. Etc. I suppose basil might be considered on-par with peppers.

a university I have never heard of

Oh! Well, that seals it right there! Everybody, Joe has never heard of Helsinki University of Technology; therefore, I'm wrong!

FYI: Helsinki University of Technology is Finland's top tech college, and is one of the top 100 schools in the world for degrees in technology-related fields (according to QS's rankings of the world's universities.).

TO THE ELECTRONICS DEPARTMENT

Good point. After all, LEDs are handled by the Underwater Basketweaving Department.

Do you expect us to follow every one of those sources the guy cites?

If you care about peer review? Yeah, I do. The fact that you're basically saying "I haven't read it, but they must be wrong!" really shows how much you think of peer-reviewed scientific research.

Exclamation points aren't indicative of hostility. They are exclamatory. Get a dictionary lady.

"The act of exclaiming; outcry; loud complaint or protest: The speech was continually interrupted by rude exclamations."

So, you were exclaiming, outcrying, offering loud complaint or protest... but in a kind, non-hostile manner, right? ;)

Of course, you will interpret it to mean whatever you want or you will just settle on one definition that suits your argument, right?

Nah, only Definition #1.

From there, you hijacked this thread

Hey, how's that "NASA sucks and here's why" tangent you dragged this into going?

even you admit it became about LED's rather than about "My hot pepper situation" that simply mentions LED's

You know, I recall the poster devoting a whole paragraph to asking about LED lights. I don't recall them asking about whether the Bush administration tried to pressure NASA scientists to deny global warming (which you brought up in a strange attempt to argue that if an organization does something wrong -- which, funny enough, they did just the opposite of what you insinuated -- then all research conducted by all groups associated with them becomes null and void, even when peer-reviewed.)

Hmm, what's a tangent: discussing peer-reviewed research on LEDs when the original poster asked about LEDs, or smearing NASA? I'll have to think about this one.... ;)

By the way: sorry for the sarcasm, but I really do find your posts amusing, so it's just coming out on its own. I get a kick out of the fact that you don't seem to realize that you're contradicting and damning yourself with every post.

Wow. That was on par with Fox News and MSNBC in the taking snippets and twisting info department. I particularly like where you try to distract anyone from realizing that financial control by government is not a legal issue and that the admin of NASA doesn't work for the government. Well, he doesn't now. But he did when he created COTS for NASA, a government agency.

For anyone interested: Radishes in June mean its the 5th harvest of radishes. It's a strategy gardeners have been using for a lot longer than I've been around in order to keep the veges coming. Of course, real gardeners understand that concept and normally utilize it to maximize yield. People that only pretend to have experience, well, they say what Karen said and reveal they really don't know as much as they think they do. Point is that it's up to anyone reading this thread - and any other thread where someone desperately tries to sound highly educated - to look at these little revealing things to determine the true value of the egomaniac posting. Do you want to garden? Or stroke someones ego? As I understand it, the point of gardenweb is to help people and be open to ideas. Not to mislead to satisfy your ego as the one who knows and not to get rabidly defensive if your idea is challenged. Everyone gets defensive or moody, but this is just nuts. Of course, I'm not much better. I was foolish enough to take up a fool's argument. Guess that makes me the greater fool.

just remember this joe.
never argue with a fool. he'll bring you down to his level and beat you with experience.

Incidentally, here's my logic on nasa vs commercial space development. this is not science, just observation.
go shoot a rocket and say you were trying to put something in space for commercial gain. how do you think uncle sam will react to that? He didn't take it too nicely when North korea did that (or so they claim) and that wasn't even in his air space.

I particularly like where you try to distract anyone from realizing that financial control by government is not a legal issue and that the admin of NASA doesn't work for the government. Well, he doesn't now. But he did when he created COTS for NASA, a government agency.

You do realize the implications of your line of argument, right? You argued that NASA was forced by the government to implement COTS, and when I pointed out that COTS came from within NASA, you argue that NASA is the government. So you're saying that they forced themselves to implement it. That's... rather cute ;)

Of course, real gardeners understand that concept and normally utilize it to maximize yield.

"Real gardeners" understand that the reason that you shade lettuce and radishes in the middle of summer is to discourage them from bolting, not because they somehow grow better in the shade. It's well known that the rate of radish root growth is directly tied to how much sun they get. The same goes for most root crops.

FYI: I'd gladly compare my full-sun radishes to your shade radishes any day. Same with lettuce. Up for some competition once temperatures cool down this fall? Or even better, competition between my LED grown plants and whatever lighting system you use? We could pick some identical growth conditions (fixed size pots, particular seed types, a standard soil, etc) and see how our growth compares.

As I understand it, the point of gardenweb is to help people and be open to ideas.

Which is why you're so open to reading research papers on LEDs, right? Or listening to others who actually have experience growing with them, right?

Not to mislead to satisfy your ego as the one who knows and not to get rabidly defensive if your idea is challenged.

Rabidly defensive -- cute, coming from a person whose posts are littered with exclamation points and words in all caps, against a person whose posts are littered with smiley faces. ;)

how do you think uncle sam will react to that?

By giving them money. That's what COTS is. :)

To launch a rocket to orbit, all you need is to fill out an application FAA waiver, which is pretty trivial for a company big enough to build rockets to do. Much more prohibitive (apart from the rocket itself) is the risk -- people generally don't like exposing themselves to the risk of having a failed launch crash and explode in a subdivision. For example, to avoid this, SpaceX primarily launches from Kwajalein Atoll, straight across the empty Pacific. Orbital launches their Pegasus rockets from aircraft so that they can carry them to non-populated areas. NASA itself avoids the risk by launching straight over the Atlantic from Canaveral.

If either side is very much set in their ways, even if the LED's or HID's blew up and set all the plants alight, they'd still love them. I respect that.
I think on a large scale perhaps HID lighting is better as you can place the lights further away where as with LED's you could only light a smaller area and not grow an entire Hydrofarm of lettuce, well you could but man thats a lot of LED's.
Neverthe less, here is something you could all enjoy.

Bye now

Here is a link that might be useful: Experiments with LED growing