The primary grow area is suppose to be 3'x3' with the supplemental area 5x5. You are going to want about 25,000 lux (~2325 foot-candles) at the top of the plant if you plan to get fruit.

Mike

Is it reasonable to expect two tomato plants to grow in the 'primary' and some lettuce in the supplemental? or is that asking two much?

Maby sneak a pepper plant or two in there?

It better be "reasonable" to expect two tomato plants - I plan on six! But I am using a HPS bulb, not MH which puts out less light.

I'm doing an experiment now, though it is still in a "seedling" stage. I have six tomato plants, getting larger under a 14 watt, all-blue, LED panel. (Four varieties: Goliath, Celebrity, First Prize and Better Boy) In about 10 days, maybe 17, depending on how fast they grow, I will transplant them into seven gallon containers, which go in an area I built just for them. For the most part, I plan to grow them organically, except when it comes time for fruiting/blooming watering time. Then I will probably use the nuits I have in the water at least once. But organically almost means giving them a good dose of compost tea every other watering until they start flowering and adding a CO2 generator in the chamber.

I did use a light meter to check the intensity, not completely at the edges of the containers - they are 14" wide so that's a bit more than 3' but close to it. I was able to get enough lumens that I should only need to run the light 15 hours a day. But again, that was an HPS bulb.

Good luck with your endeavor and do keep us informed!

Mike

My plan is to chart their growth and production over the next five months or until they quit producing fruit - whichever comes last.

Thanks Word. That's good to know! I got into this.. uhh.. A week ago? And it's quite a learning curve!

If you have a regular metal halide bulb, it will be deficient in far red light. In my experience, the growth rate of plants can be more than doubled by adding an equal wattage of incandescent light (a rich source of far red) to regular metal halide. It is easy enough for you to verify this by shining an incandescent floodlight on one plant for comparison.

A more efficient source of far red light than incandescent is Philips White Son®. Look at the spectral distribution chart:

The part on the right that would be between 700 and 800 nm is far red light. I have no experience with Philips White Son®, but, theoretically, supplementing a regular 400 watt metal halide bulb with a 100 watt Philips White Son® bulb, should more than double the growth rate of plants.

Ok, the White Son is a HPS bulb, so it's going to need another ballast, and reflector assembly, yes? I may look into it, but at the moment, the budget doesn't really allow for it. I got my metal halide assembly with bulb for $40, and the 50 watt Philips White Son is more then that!

What about adding a some 2700k florescent lights? Would that add enough far red to be interesting? Also: is there a decent place to get HPS fixtures for something like 100 watts?

Thanks,
Steve

Ok, the White Son is a HPS bulb, so it's going to need another ballast, and reflector assembly, yes?

Yes.

What about adding a some 2700k florescent lights? Would that add enough far red to be interesting?

No. First, test supplementing your MH with a regular incandescent light bulb to see if it improves growth. Only if it makes a big improvement should you think of investing into more efficient far red supplementation. Also, there are special MH bulbs with adequate far red. For all we know, you already have one.

The cost of the bulbs, ballasts and fixtures should be amortized over their lifetimes and compared with the cost of electricity for those times.

Ok, will do! I'm gonna hit a pepper plant with a 100w incandescent and see it there is any difference. The bulb came with the MH, and I have no idea as to it's specs. I'm haven't looked at it for any model information.

It better be "reasonable" to expect two tomato plants - I plan on six! But I am using a HPS bulb, not MH which puts out less light.

I'm doing an experiment now, though it is still in a "seedling" stage. I have six tomato plants, getting larger under a 14 watt, all-blue, LED panel. (Four varieties: Goliath, Celebrity, First Prize and Better Boy) In about 10 days, maybe 17, depending on how fast they grow, I will transplant them into seven gallon containers, which go in an area I built just for them. For the most part, I plan to grow them organically, except when it comes time for fruiting/blooming watering time. Then I will probably use the nuits I have in the water at least once. But organically almost means giving them a good dose of compost tea every other watering until they start flowering and adding a CO2 generator in the chamber.

I did use a light meter to check the intensity, not completely at the edges of the containers - they are 14" wide so that's a bit more than 3' but close to it. I was able to get enough lumens that I should only need to run the light 15 hours a day. But again, that was an HPS bulb.

Good luck with your endeavor and do keep us informed!

Mike

My plan is to chart their growth and production over the next five months or until they quit producing fruit - whichever comes last.

>> Ok, will do! I'm gonna hit a pepper plant with a 100w incandescent and see it there is any difference. More than likely, it will - you will get leggy plants. The higher the far-red to red ratio your plants get, the more the stems will grow. Leaves do not use far-red light, only the stems.

Mike

Leaves do not use far-red light, only the stems.

That is untrue.

Far red combined with other wavelengths of light increases photosynthesis via the Emerson Enhancement Effect, and the resulting sugar feeds all plant parts. Here is a paper on the Emerson Enhancement Effect:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC550018/pdf/plntphys00410-0010.pdf

Look at this figure,

in particular, the curve with the writing, "with supplementary light." That represents the increment in photosynthesis rate produced by adding monochromatic to white light. The authors poorly word the graph descriptions so to properly interpret these curves you have to check the equation representing the "enhancement" curve,

(R(far red + supplementary lights) - R(supplementary light))/R(far red light)

to see that the "enhancement" curve is obtained by dividing the "with supplementary light" curve by the "without supplementary light curve" which implies that the "with supplementary light" curve represents

R(far red + supplementary lights) - R(supplementary light)

and NOT R(far red + supplementary lights), as might, otherwise, be interpreted.

Note that the additional amount of photosynthesis produced by adding monochromatic light levels out for far red between 720 and 740 nm and there is no indication that the curve wouldn't continue to be level well past 740.

Furthermore, there is some evidence elsewhere that something like the Emerson Enhancement Effect occurs near the violet end of the spectrum. Metal halide light is typically very rich in violet light. The reason that white clothes glow unusually bright under MH is that laundry detergents contain fluorescent bluing that is activated by violet and ultraviolet light.

okay.. so.. is my MH bulb gonna work out okay then?? or..?

Now i'm somewhat overwhelmed with info. Do i need far red light supplementation?

One study does not a fact make. A high far-red/red ratio increases stem growth. It does this because the plant thinks it is shaded and thus if the soil's moisture content is normal, as is the light intensity, the plant responds by trying to grow taller in order to receive more light. Photosynthesis can be enhanced but it is directed toward growth in height, not growth in biomass. If incandescent bulbs offered increased production, greenhouse growers would be using them, or using bulbs that offer more far-red light.

Mike

One study does not a fact make.

Neither do the unsubstantiated statements, shamelessly made with great conviction, of one person, such as yourself. If you Google "Emerson Enhancement Effect", you get 2,790 hits. If you restrict this to PDF files, you get 83 hits. That is not one study.

Here is a relevant abstract in which "Emerson" is not even mentioned, http://aob.oxfordjournals.org/cgi/content/abstract/38/3/613

A high far-red/red ratio increases stem growth.

True, see http://www.mobot.org/jwcross/duckweed/phytochrome.htm#tetrapyrrole but

1. Depending on the plant species blue light can shorten stems. For tomato, see http://www.actahort.org/members/showpdf?booknrarnr=305_14. MH has much more blue light than HPS.

2. The far-red/red ratio of an appropriate MH incandescent combo is less than that of direct sunlight which is 1/1.2 = 0.83.

3. The ratio is measured at peak phytochrome sensitivities at 730 and 666 nm. The absorption spectra of phytochrome is

See that minor Pr peak at 400 nm? As I previously said, MH has a huge amount of violet light around 400 nm. I expect violet light would cause a phytochrome response similar to a FR:R ratio of 1.

In contrast, the peak increase in photosynthesis due to Emerson Enhancement in that paper was between 680 and 695 nm.

4. Stems can be shortened in other ways, e.g., (I read somewhere) growing plants at a higher dark period than light period temperature.

If incandescent bulbs offered increased production, greenhouse growers would be using them, or using bulbs that offer more far-red light.

If the supplemental greenhouse lighting is during the day, there is already a surplus of far red from daylight, even when the sky is heavily overcast. Thusly, incandescent supplementation would be pointless during the day.

Do i need far red light supplementation?

No, but it helps.

It's not just me - hundreds of researchers agree. If you Google stem elongation red far-red ratio artificial lighting you get over 5,000 hits.

http://www.freepatentsonline.com/5269093.html
(an excerpt) The stem length was increased significantly with the FR irradiation for 3 days after planting in the treatments C and D. The longer the treatments, the greater became the differences between the different treatments. With the treatment by FR irradiation for 8 days after planting, the stem length extended 3.8 times more in the treatment D than in the treatment A, and the leaf/stem dry weight ratio was 2.7 in D and 5.8 in A.
As the FR irradiation increases in treatment, the stem length and the internode length were extended. So, the plant height was increased and the leaf area became larger. Since the photosynthesis caused by FR irradiation can be ignored, the increase in dry weight was considered to be caused by an increase in the photosynthesis that was possibly caused by the shortened distance between the luminaires and the plants.
It might also be caused by the elongated internode length which resulted in decreased mutual-shading and an increase of the leaf area, enabling to accept more photons.

Even more telling is this one:
http://ncr101.montana.edu/ceug/pr-pot.pdf Be sure to look at Page 9.

Mike

It's not just me - hundreds of researchers agree.

I never disputed that far red increases stem length. What part of "True" didn't you understand in,

"A high far-red/red ratio increases stem growth.

True, see http://www.mobot.org/jwcross/duckweed/phytochrome.htm#tetrapyrrole but"?

Your statement, "Leaves do not use far-red light, only the stems." is false. At best, it is a big lie that you tell yourself.

>> "Leaves do not use far-red light, only the stems." is false. At best, it is a big lie that you tell yourself. If they do not absorb it and let it pass through, how do they use it?

http://www.actahort.org/books/711/711_24.htm
Plant leaves filter light. Specifically, leaves allow more far red light (720Â740 nm) to pass through than red light (660Â680 nm), thus altering the red:far red ratio below them. By altering light quality, plants perceive canopy shading via alterations in phytochrome photoequilibria that can result in increased stem elongation and reduced branching among other responses.

Seriously, you are welcome to add all the incandescent bulbs you want - your energy supplier will send you a Christmas Card for being such a great customer. And if you want tall plants, even more reason. Of course, it might mean you will have to raise your lights significantly higher, meaning less penetration, but that's your choice. It doesn't make any difference to me.

All I try to do is use what growers who have studied how to best raise plants under artificial or supplemental light to improve my production, then pass this on to others. In no way did I try to incur your ire but at the same time, I would be remiss not to point out that raising the far-red/red ratio is normally not a good idea.

Happy trails,

Mike

I've got to say. Compact definitely sounds like more of what i'm going for. I've got limited room under my lights if i want to keep stuff alive. I may add far-red for flowering, but at this point, i'm thinking probably not.

Also: You guys are hard core. For srs.

If they do not absorb it and let it pass through, how do they use it?

http://www.actahort.org/books/711/711_24.htm
Plant leaves filter light. Specifically, leaves allow more far red light (720Â740 nm) to pass through than red light (660Â680 nm), thus altering the red:far red ratio below them.

It says "more" not "all" far red light passes through the leaves. Do you know the difference between "more" and "all"? A portion of the far red light that does not pass through the leaves is used for photosynthesis.

Geez,

What part of "Plants use light in the 400-700 nm range for photosynthesis" don't you understand? Does it say 400-740 range?

Go ahead, increase the far-red/red ratio to your heart's content. It's your plants and you can and should do as you think best.

I don't, and neither do most people, want plants with elongated stems and a wider internodal distance. If you like yours that way, fine. My aim is not to convince you to change, it is to let people know what effects will occur from the suggestions you make. That's all.

Happy Trails,

Mike

Gentlemen, You've both stated your case, You've both provided a not insignificant amount of information to review. At this point anyone reading the thread can make the decision for themselves. Let's not let this get personal.

-Steve

Works for me! I really do believe everyone needs to find the method that works best for them and not rely solely on reading posts.

Mike

What part of "Plants use light in the 400-700 nm range for photosynthesis" don't you understand?

You are hallucinating the word "only" in that sentence. It doesn't say "only in the 400-700 nm range". If it did, it would be a lie.

Works for me! I really do believe everyone needs to find the method that works best for them and not rely solely on reading posts.

That's a hypocritical statement coming from you, since my advice to the OP was to TEST supplemental incandescent light on one plant and most of your efforts seem to be directed against him even trying it.

You say tomato, I say tomato. Wow, I'm worn out after reading all that BS. Anyway, Steve to answer you questions:

1.I like your idea of the plant setup. What about putting the taller plants(tomato) at the back of the grow area and put your shorter plants up front. That way when your tomato plants get tall, the lettuce and peppers still get sufficient light and are easier to work with. Another idea to conserve light would be hanging white shower curtains, as false walls, with black poly sheeting taped to the outside. That will really hold in the light and up your light efficiency.
2. A 400 watt Metal Halide needs to be around 12" from the tops of your tallest plants. It If it's air cooled, you might be able to lower it to 8". Like Mike said, a 3'x3' area is what a 400 watt covers.
3. To all those red light lovers and haters, you only need the red spectrum for flowering/fruiting, if that. You can totally fruit a tomato plant under a metal halide. Go to my website to see the pics. I'm doing an experiment with two tomato plants, one under a HPS and the other under a MH. The one under the metal halide actually has twice as many tomatoes. If you want to add more colors to your setup, you can invest in a HPS conversion lamp, which operates on a metal halide ballast. It will add a redder spectrum and add 6,000-9,000 more lumens. The light bulb costs $120.

Hope this helps. Erich

Here is a link that might be useful: Urban Garden

Erich,

Actually, a MH bulb provides more PAR light per lumen of foot candle than an HPS bulb does. The downside is that an HPS provides more PAR light per watt.

Rather than spending $120 on a HPS conversion bulb that will operate in a MH ballast, the better idea is to buy a system that will support both. Then a MH conversion bulb (400 watt) is less than $50.

Mike

I have been messing around with both MH and HPS for decades and I have had tremendous success using Metal Halide by itself, although I do use both types. I am of the opinion, from experience, that pumping up the red for fruiting/flowering is highly overrated, but not entirely bogus. I do remember once reading some biology course material which did associate the chlorophyll reactions under the red wavelengths(as opposed to blue) with directly assimilating phosphorous in the Calvin/Krebs cycle - if I remember correctly. Extra phosphorous is also traditionally boosted during fruting /flowering as you "pro-reds" surely know.

About 20 years ago I visited what was then our town's main, hip hydroponics/gro-shop, located on the slope of a small hill. They kept bragging about how well their tomato plants did under HPS alone. I did not bother to point out to them that ALL of their plants with HPS setups were placed next to their 12' high total glass outer wall with a completely unobstucted view of the blue, blue sky. They hardly even need to add the grow lights! Needless to say, I didn't take much of their advice.

Zink

>> Actually, a MH bulb provides more PAR light per lumen of foot candle That should be OR not of.

Mike

I have been messing around with both MH and HPS for decades and I have had tremendous success using Metal Halide by itself

In all those decades, did you ever test adding incandescent to regular MH?

My experience was that growth using only Sylvania Metal Arc light was poor, but that was the only MH I ever used.

I believe the Sylvania Metal Arc is in fact the bulb i'm using. However, seeing as so far i've killed all my seedlings, I haven't had much of an issue with grow lights yet! Haha.

Thanks for all the advice everyone! Gonna stick with the MH Bulb for now. If my Tomatoes don't fruit properly, I will look into far red.

Far red will NOT stimulate fruiting - red will.

Mike