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T5 lighting experts needed

Posted by yucatan (My Page) on
Sun, Mar 28, 10 at 18:03

I'm a fairly new indoor gardener. Despite lacking years of experience growing plants indoors, I have read plenty of articles, books and experiments so I am familiar with much more than your typical indoor gardener. But I still have some questions...
First, some background:
I am growing tomatoes and chiles strictly under a 4-ft. High-Output T5 Fluorescent unit that has 2 bulbs (6500 K and 3000 K) at 92.5 lumens per watt to equal 10,000 lumens. My grow area is 2 x 4 ft. and covered in Mylar. In the seedling and vegetative stage, my plants were strong and healthy. In the flowering stage, my plants were less than satisfactory and my yields were very low.
I realize that most indoor lighting research deals with HPS/MH systems and this information does not necessarily apply to my situation. Therefore, I was wondering if I could receive some veteran advice here:
1- Please explain the required mols/day and daily light integral (DLI) for attaining optimal results for tomatoes and chiles grown in a 2x4-ft. area if using HO-T5's, possibly with CFL supplementation.
2- What is the best ratio of cool white 6500k to warm white 3000k bulbs for my goal, and will the ratio change depending on the plant's life stages?
3- If I were to fruit under HO-T5's, maybe with some CFL supplementation, how many bulbs are needed to have satisfactory yields? I'm okay with buying more HO-T5 units, but HPS/MH systems rack up too much intial costs and electricity costs for my budget.
4- I read that long-day and day-neutral plants perform best with 18 hours of light/day during the vegetative stage and 12 hours of light/day during the fruiting stage. But this information assumes that the grower is using HPS/MH lights. Does the same concept apply if using HO-T5's?


Follow-Up Postings:

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RE: T5 lighting experts needed

I am no expert but for flowering you should use mainly the 3000k as it is closer to red in the visible light spectrum. Not saying that you shouldn't use the 6000k but the fruiting process calls for more 3000k so if you want to have more successful yields then I would suggest a higher ratio of 6000k to 3000k. I would do a 1:3 ratio between the 6000k and the 3000k respectively. Using 4 of those T5's will be a decent amount of lumens (with your calculations, approximately 40,000) but considering my 400watt HPS bulb emits (38,000 lumens) then you should be just fine.

Also, what kind of lighting cycle did you use?? I will assume you know a decent amount about lighting for indoor plants after reading your post, but did you do the 12/12 cycle? Also, what kind of fertilizers are you using?? Did you change fertilizers during the flowering phase? Oh and one more thing, what was your temp and humidity for day and night during your fruiting (if you remember)?


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RE: T5 lighting experts needed

Hi ethnobotany,

Thanks for your advice. I have successfully grown outdoors in the past, but the problem I am encountering now are with insufficient lighting. Nevertheless, to answer your questions:

I used 18/6 during the vegetative stage and 12/12 during the flowering stage, upon which I boosted phosphorous and lowered nitrogen. I'm also supplementing magnesium and calcium and supplying a fair amount of potassium. I'm using organic fertilizers for my container plants. Now, I know after reading several articles here that my choice of fertilizer may receive a lot of speculation, but I find that building an organic, nutrient rich soil makes plants happy regardless of their growing environment. The soil feeds my plants evenly over time, not frequent applications of quick release fertilizer which can cause chemical burn.

My temperatures range from 70 to 78 degrees and the humidity averages around 38%. I know the ideal humidity is more like 55%, but that's not realistic in a small apartment without C02 supplementation or many plants growing close together.

Regards,

Robert


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RE: T5 lighting experts needed

What's up yucatan. I'll try to help you out as best I can.

1- "Please explain the required mols/day and daily light integral (DLI) for attaining optimal results for tomatoes and chiles grown in a 2x4-ft. area if using HO-T5's, possibly with CFL supplementation."

I don't know about the technical math on lighting, but I do know that for an 8 square foot area, you need at least 400 watts of high intensity light, to produce some good veggies. Like ethnobotany said, somewhere around 35,000-40,000 lumens. Since your using fluorescent light instead of MH/HPS light, I would up the lumens to 50,000. You should get plenty light penetration, with that number.

2- "What is the best ratio of cool white 6500k to warm white 3000k bulbs for my goal, and will the ratio change depending on the plant's life stages?"

I would use an even mix for vegetative growth and supplement with 3,000k CFL's during flowering.

3- "If I were to fruit under HO-T5's, maybe with some CFL supplementation, how many bulbs are needed to have satisfactory yields? I'm okay with buying more HO-T5 units, but HPS/MH systems rack up too much intial costs and electricity costs for my budget."

I think we've already been through this, but each 4' tube is 5,000 lumens, so you're wanting to reach at least 40,000 lumens. You can mix and match however you want, to get to that number. Whether it be 8- 4' tubes or 6- 4' tubes and 10,000 lumens of CFL. Whatever works best for your grow area.

4- "I read that long-day and day-neutral plants perform best with 18 hours of light/day during the vegetative stage and 12 hours of light/day during the fruiting stage. But this information assumes that the grower is using HPS/MH lights. Does the same concept apply if using HO-T5's?"

It makes sense to me that if your using fluorescent light to grow your plants, the more light the better. Tomatoes and peppers need at least 4 hours of darkness per day for sufficient flowering. That doesn't mean you have to give them 20 hours of light. I would give them at least 15 hours of light per day. That's what I had my light's on for my peppers and they grew just fine. Hope this helps.


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RE: T5 lighting experts needed

Thanks urban...So you're saying that 40,000 lumens worth of HO-T5 light won't penetrate as deeply as 40,000 lumens worth of MH light, and therefore it's best to have a little more?


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RE: T5 lighting experts needed

It's hard to say for certain. Maybe not. I just found this article from prolighting's website. Pretty interesting, if it's true? From what I've seen in my grows, with HO T-5's, I'm a believer:~)

-(HO) T-5 lighting:
The secret to these fixtures performance lies in the multi-faceted, enhanced aluminum reflectors that encase each lamp and focuses the output for maximum intensity. Coupled with the excellent color rendering, lumen maintenance, and energy efficiency of today's fluorescents, fluorescent high bay fixtures can be used in applications normally reserved for HID's.

Standard 400-watt metal halide fixtures rated for 36,000 initial lumens lose up to 45% of their lighting ability through depreciation and fixture inefficiencies. When compared to only a 6% loss of the T5HO Fluorescent High Bay rated for 20,000 initial lumens, the maintained lumen output is virtually the same.

A four-light 54-watt HO T5 high bay requires only 239 watts as compared to the metal halide which consumes 454 watts, a dramatic 50% savings in energy usage. In addition, the fluorescent high bay produces brighter, more even illumination with features like instant on, built-in switching and low-temperature operation.


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RE: T5 lighting experts needed

Yes. I'm aware of all of that, along with a few more advantages. That is why I'm surprised more people aren't using HO-T5's to fruit plants indoors. 99.9% of the books, experiments and articles that I encounter fruit plants strictly using HPS/MH units. Someone needs to write a manual or do an experiment so that HO-T5 growers can have some sort of foundation.


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RE: T5 lighting experts needed

" That is why I'm surprised more people aren't using HO-T5's to fruit plants indoors "

Most people fruit plants outside where the light is FREE

" Someone needs to write a manual or do an experiment so that HO-T5 growers can have some sort of foundation "

Why not YOU?


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RE: T5 lighting experts needed

I think the reason you don't see many arcticles about HO T-5's is because it's new technology. They've only been out for a couple years. Technology keeps growing exponentially every year. Next thing you know, we'll be using plasma lights to grow plants. Seriously, check out this link.

Here is a link that might be useful: Plasma grow lights


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RE: T5 lighting experts needed

DLI needed for good production of tomatoes and peppers: >20 mols per day. I've posted this in another thread you started.

Mike


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RE: T5 lighting experts needed

Mike I'm surprised you even replied here. I wouldn't be surprised if this wasn't the last thread on the same subject. The OP will probably continue until he/she hears what they want to hear.

There are no experts on T5s and growing plants. Fluorescents are fluorescents are fluorescents. My T12s put out 5,000 lumens ea. I can grow tomatoes and peppers to maturity under them but I'm not going to pay the electric co. to do it when the sun is free. You need at least one more set of lights of the same caliber. 3/1 3000k/6500k. It is that simple and no scientists needed...


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RERE: T5 lighting experts needed

Oh! and 14-16 hours light regardless of the stage the plant is in.


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RE: T5 lighting experts needed

@taz: My original concerns either go unanswered or get lost in conversation about other topics. I don't know enough about this to write a guide, but I also don't think anyone here can write one either.

T5 Fluorescents at 5000 lumens cost me $3/month in electricity so I don't know why you're saying it's too expensive. Also, I am aware the sun is free but my high rise apartment has no access to enough sunlight to accomplish this with good results. So please stop telling me the sun is free. I know this, and it will still be irrelevant to my situation.

@wordwhiz: Eric Runkle's research says that a minimum of 15 mols of light per day will get the job done. How many T5 bulbs at 5000 lumens a piece will accomplish this in a 2x4 grow area less than 12 inches from the plant tops? Sorry but I forgot the equation.


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RE: T5 lighting experts needed

" My original concerns either go unanswered or get lost in conversation about other topics "

Your questions have been answered, It's not our fault you cannot see.

" I don't know why you're saying it's too expensive "

You're putting words in my mouth.

You are going to do what you want no matter what answers you get. Just do as you wish and quit asking the same questions over and over. I and I'm sure others are growing weary of your posts. You continue to disregard the info given so please go elsewhere to get it. DG maybe? Good luck!


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RE: T5 lighting experts needed

@taz: there was no reason for that comeback. you said the sun is free and that im basically dumb for growing the way i am. Despite what you think, you have not really answered my original concerns. Prove that you have and you will win.


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RE: T5 lighting experts needed

I never said you were dumb, but if you insist! I can only tell you what I know and I have answered to the best of my knowledge. I can offer no scientific evidence, only what I have learned from experience and I grow much much more than just toms and peppers. I don't need to prove myself to some stranger on the WWW but don't mind sharing my experiences with deserving individuals. BTW what's the prize?


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RE: T5 lighting experts needed

Your advice is appreciated, but hardly in need of being deserved. If you cannot provide any answers, that's fine, but I was looking for more than personal opinion. I can tell you how I enjoy my steak, but that's based on personal opinion. Do you understand the difference?


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