Nutrition in plants grown under lights vs sunlight

[James Keller]

I've got a friend who has a growing business making blended green drinks and selling them to health food junkies, hippies, people on cleanses, etc.  The drinks are mainly based on romaine lettuce.  Since my system runs cold water for my trout, I am mostly growing leafy greens and lots of romaine.  So I decided to offer to sell her some of my romaine this winter to put in her drinks.  She likes the idea, but the one question she raised is whether the lettuce grown under lights are less energy/nutrient dense than those that she currently gets from traditional farms grown in sunlight.  

I've searched the forums here and have not seemed to find anything relating to this issue.  Does anyone have a place to look for research on this issue? 

Thanks!

James

[Michael J. Tompkins]

wow..... good luck with that! Can't wait to hear the results if you find out...

Michael

[Roger]

James - I work in a hydroponic shop and have never heard people concerned with the nutritional content of the food they are growing.  The nutritional density of veggies/fruit is determined by the quality of the plant food used and how well the plant is taken care of while growing (ie stressed plants will exert more energy at maintaining life).  

Lighting can effect how quickly a plant grows and if it is a flowering vegetable how many fruits/veggies it will set.  Since you are growing romaine you won't need any expensive HID lighting.  High intensity T-5 fluorescent lights will do a great job on leafy greens such as romaine.  Feel free to research if you are skeptical, but plants require a certain light.  Whether they are getting that light from the sun or from artificial lighting doesn't matter.  Lumen output does matter, that is the intensity of the light.  High output T5s will do the job.  You can get an 8 bulb fixture that is 4 feet long for about $200 dollars.  Of course there are smaller fixtures, but this will maximize your growing area.

[Carey Ma]

I concur with what Roger said. Nutrient density has more to do with what your plants are fed than source of lighting. If your plants are green and healthy looking, they are probably getting enough light. Make sure your system is properly stocked and wait until it is mature before you start growing and you should be fine.

Here we grow 365 but do not use supplemental lighting.

@ Roger; plant lighting is actually measured in PAR (photo reactive radiation) rather than Lumen.

[Vlad Jovanovic]

Hi Roger...How is a $200 8 bulb T-5 fixture cheaper than a 400Watt HID fixture that will cover the same 4'x4' area (yeah, I'm aware of what the "charts" and hydro sales people say...but the man is talking lettuce not MJ)? Both in initial cost as well as cost to maintain has consistently been cheaper with HID's...I'm mostly thinking of having to change out the tubes every 6-7 months because PAR... Photosynthetically Active Radiation does noticeably decrease after such a time, and if I don't change out the tubes my plants tend to languish until I do.

HID lighting is hands down still the cheapest and most hassle free (no height adjusting tubes to within a couple inches of plant tops...sometimes daily) lighting option for anything but the smallest, tiniest home system.

No toxic mercury spewing into your system water should a tube decide to blow out...necessitating a complete 'start over'.

I like the old style Phillips brand magnetic HID ballasts, sure they are not dimmable, they don't have crazy spaceship aluminum cooling fins or lights and diodes that blip and glow like the new digital ones...but they are total workhorses and very, very reliable... and can be had for much, much less than the digital ballasts...

IMO, in the flouro realm the only way that you will get off any cheaper and still have a decent amount of light to grow with is if you wire up T-8's ODNO (OverDriveNormalOperation) style. It's a very easy modification, you hardly need to be an electrician or anything). Of all the flouro tubes out there T-8's are the 'sweet spot' for this mod. It's a good way to get a lot more light out of them for cheap. Especially if you pick up a bunch of fixtures on craigslist or from an office building that is being renovated. If someone goes that route...know that you can only do this modification with magnetic T-8 ballasts and not the digital T-8 ballasts...which is great because those are even cheaper. There are many good tutorials on  the web...but basically you are just running an extra lead into the tube...that's it. To a degree, the High output T-5's come ODNO'd right out of the factory...

As to nutritional value...I agree with most of what was said...although there have been studies done by some Chinese researchers that showed UV light had a positive impact on the nutritional content of lettuce in the experiment that they conducted. This is easily be accommodation by using CMH (Ceramic Metal Halide) bulbs, since they are full spectrum...UV included...  

[Jon Parr]

CMH bulbs...better, cheaper, longer lasting, better for the environment, more like the sun than any bulb I've seen.

I have to disagree that lighting and light source are less important than available nutrients, regarding nutritional content of finished lettuce. Lighting is paramount. In fact, low light levels cause high nitrate levels in lettuce, and such lettuce is converted to carcinogens after injestion. That's right! Not only is low light lettuce less nutritious, it's carcinogenic. This was news to me, but I recently learned this from Jesse Hull at an AP workshop. This article backs it up, and will be a good read for you James:

http://www.benthamscience.com/cnf/sample/cnf5-4/D0003NF.pdf

Lettuce is a low nutrient feeder, and a low nutrient yielded, basically green fluff. Ironic that it is the base for the nutritional drink in the OP. Better romaine than iceberg, I suppose. But seriously, don't go spending money on nutrients in lieu of lights thinking you will get a more nutritious product. Sunlight is best, no denying it, but adequate artificial light will be just as nutritious, if not more so. Why? Because artificial light can be maintained at adequate levels, where winter sun and cloudy days may be inadequate. Interesting to note also in the above link is that nutritional content of lettuce was markedly improved by the addition of seawater. Hmmm

[Vlad Jovanovic]

Nice find Jon.

Guess the key phrase is for the OP is "adequate lighting". 

[James Keller]

Thank you all for your insights, I'm taking all this into account and may have a good case to make :)

[Roger]

Vlad - I wasn't suggesting James had to necessarily stick with a 8 bulb T-5 fixture I suggested.  Generally a 400 watt HID light system, from my experience, is going to have an initial investment of $400 dollars.  I own both type of systems and only replace bulbs in both systems once a year.  Granted my PAR and/or lumen output drop throughout the course of the year, but it does not significantly decrease plant development as long as I replace the bulbs (both fluorescents and HIDs) once a year.  As stated originally, I only suggested the T5 fixture because from my experience it is cheaper than a HID system.

I also have no experience with growing MJ and would never suggest a lighting system based on who the hydro industry caters to.  I'm simply giving advice based on my personal experience.  Also, I'd like to state that metal halide bulbs to contain mercury much like fluorescents.  Both bulbs can break and leak mercury into your system.  This of course is alleviated in a HID system as long as you have a reflector with a lens; however, I've witnessed many people using HID lighting that have a open reflector.  Last, lighting can be measured in either lumen output or PAR output.  From what I understand PAR output is a better judgement of how effective you lighting is.  Lumen output actually just measures the intensity of the light being discharged from the bulb; whereas, PAR measures the light's ability to reach through the canopy of the plant towards the base of the plant.  

Good luck with whatever light system you decide on James!

Vlad Jovanovic said:

Hi Roger...How is a $200 8 bulb T-5 fixture cheaper than a 400Watt HID fixture that will cover the same 4'x4' area (yeah, I'm aware of what the "charts" and hydro sales people say...but the man is talking lettuce not MJ)? Both in initial cost as well as cost to maintain has consistently been cheaper with HID's...I'm mostly thinking of having to change out the tubes every 6-7 months because PAR... Photosynthetically Active Radiation does noticeably decrease after such a time, and if I don't change out the tubes my plants tend to languish until I do.

HID lighting is hands down still the cheapest and most hassle free (no height adjusting tubes to within a couple inches of plant tops...sometimes daily) lighting option for anything but the smallest, tiniest home system.

No toxic mercury spewing into your system water should a tube decide to blow out...necessitating a complete 'start over'.

I like the old style Phillips brand magnetic HID ballasts, sure they are not dimmable, they don't have crazy spaceship aluminum cooling fins or lights and diodes that blip and glow like the new digital ones...but they are total workhorses and very, very reliable... and can be had for much, much less than the digital ballasts...

IMO, in the flouro realm the only way that you will get off any cheaper and still have a decent amount of light to grow with is if you wire up T-8's ODNO (OverDriveNormalOperation) style. It's a very easy modification, you hardly need to be an electrician or anything). Of all the flouro tubes out there T-8's are the 'sweet spot' for this mod. It's a good way to get a lot more light out of them for cheap. Especially if you pick up a bunch of fixtures on craigslist or from an office building that is being renovated. If someone goes that route...know that you can only do this modification with magnetic T-8 ballasts and not the digital T-8 ballasts...which is great because those are even cheaper. There are many good tutorials on  the web...but basically you are just running an extra lead into the tube...that's it. To a degree, the High output T-5's come ODNO'd right out of the factory...

As to nutritional value...I agree with most of what was said...although there have been studies done by some Chinese researchers that showed UV light had a positive impact on the nutritional content of lettuce in the experiment that they conducted. This is easily be accommodation by using CMH (Ceramic Metal Halide) bulbs, since they are full spectrum...UV included...  

[Jon Parr]

Roger, brother, if you stick your neck out there you gotta expect a swing of the axe, eh? You work in a hydro store, give it to us straight...

8 bulb t-5 fixture is more like $250-300, right? Plus bulbs at $50-75, plus tax an shipping, totals more like $400 than $200. Compare:
http://www.plantlightinghydroponics.com/new-wave-4ft-8lamp-40000-lu... now even though it claims 40k lumens for a 4' x 4' pad, we really know that it covers a 2' x 4', maybe 3' at a stretch. But what the hell, call it 4x4.

Now a 400 watt HPS really costs more like $200, right. Be honest. Here's a whole kit including bulb for $155. http://www.plantlightinghydroponics.com/econowing-400w-hps-crop-mas... So, easily under $200. Even the most overpriced, top of the line product will be less than $400. Now that one shows 50k lumens for a 5' x 5' area. Again, what the hell, call it 4'x 4'.

Same wattage, half the initial investment for HID, and I'll bet my right nut (I can't bet my left, as I just wagered it in another thread a few minutes ago) it will out produce the t-5's by double. Oh, and bulbs outlast t-5s in every way, replacement is $20 for HID, at least $50 for t-5's. Now I like t-5's just fine, but you need to back up your claim. You work in a hydro store and don't have any experience growing MJ? If that's true, you should quit. That's like a vegan working at a steak-house. You've never been asked about the nutritional yield in plants grown with artificial light? That's because hydro clients don't expect nutrition from their crop. I get asked that question all the time, probably because I don't work at a hydro store. You wouldn't recommend a light based on the hydro industry's chief client? Why not, they know their stuff.

I'm really not trying to pick a fight, just trying to keep it real. HID is cheaper and better than flouros, period. Let's not forget that flouros must be used as the only source of light as well, because the fixture blocks the entire area of natural light. HID can be used as supplemental light because of its small footprint. A chrome-dome with remote ballast casts almost no shadow.

Lumens are a measure of light visible to the human eye, and because of the particulars of the eye, lumens stack more points in the greens, and taper off markedly on each side, tallying nothing for UV or infrared. Since plants don't use green, and do use UV and far reds, lumens are a piss poor unit for measuring plant light needs. PAR is much much better, but sometimes hard to find a published rating. How deep light penetrates a canopy is dependent on light "intensity". 50k lumens from a pinky-sized arc tube? Very intense, very deep penetration. 40k lumens from 8 sq ft of t-5 tubes? Very weak, very poor penetration. My beloved CMH bulbs only put out like 35k lumens, as opposed to 50-55k for the same wattage HPS, however I have seen better results from CMH. This is because the lumens rating sucks. I've never looked up PAR rating for the two. I'll do that shortly.

[Jon Parr]

Oh yeah, and you're right, all flouro's and HID contain mercury, true. But everyone commonly breaks flouro's, and HID's seldom break (well, maybe MH break often, but I don't use them). In fact, Philips CMH bulb is rated for open fixture, no glass shield. It is damned near impossible to break both the outer glass and the arc tube. The arc tube is wrapped in wire to prevent molten projectiles, and the outer glass is built to withstand internal rupture. Likewise, the arc tube is made to withstand the outer glass failure. Not so with any flouro's.

[Vlad Jovanovic]

No worries Roger. It just seems that our personal experiences vastly differ. I've never even seen an 400Watt HID set-up that was selling for anywhere near $400 let alone bought one. Mine were all much, much less than that.

Jon brought up a number of very good points (not the least of which is that no-one is here to pick a fight :) and not to flog a dead horse, but over the decades I've used T-12's, T-8's, T-5's, PL-L (currently I'm pretty happy with that one...still comes with all the baggage of other flouros but I'm digging the tri-phosphor standard, the CRI is really nice), MH, HPS, the old school first gen CMH's and some new combo HPS/MH HID's (like the Phillips Son-T-Agro Plus') and honestly no matter how I work the numbers HID is cheaper to own/run and grows the most amount of plant mass Watt per Watt. That has just been my experience over the years. Just about every commercial and serious hobby grower I've ever talked with on the subject shares similar conclusions. Now, I'm not saying your experience is not valid, I'm not saying that at all, just that I can't wrap my mind around how flouro's would be cheaper to run (when you look at all things fairly and from a business as well as practical perspective).

Yeah, HID's contain mercury as well of course, but like Jon says, it is contained within the arc tube, many of which are further protected with mesh...and then the arc tube itself  is surrounded by an outer envelope of borosiliacte glass. Flouros are much more fragile in comparison... 

Wasn't trying to pick on you or anything...the whole point was to try and steer James in the direction of thinking things through with his lighting decision...put it down on paper...Watt per Watt, Lumen per Lumen, dollar per dollar... 

[Roger]

Great points both Vlad and Jon!  Thanks for all the information you've shared.