T5 Fluorescents...Over 75% Green Spectrum?

[jawnroot]

I'm looking into buying a few high output 3000K T5's to mount on the wall as supplemental bloom lighting. I've heard some reports that these output as much as 75% of their light in the green spectrum. In other words, although they're rated at 2000 lumens per bulb, each bulb is only putting out about 500 lumens of light that is usable to plants...at least according to the somewhat dubious theories I've heard.

I've perused a few spectrum charts, and from what I can see the 3000K bulbs have minimal output in the green band. However, the same people that said they put out a majority of green also said spectrum charts can be misleading.

I suppose the bottom line is that I don't want to be spending a decent chunk of change on T5's if they are going to do little or nothing for me. I would just use low wattage HPS bulbs in their place, but with the space I'm working with, T5's (or some other fluorescent tube) would be about the only practical option.

Just to give you a general idea of the setup: I plan on mounting a 150 watt ceramic MH vertically in between two relatively small plants. This would pretty much leave the outside edges of both plants unlit. I had intended to mount the T5's vertically on the far walls, so that those sides of the plants would be lit.

 

[ProGroWannabe]

Sounds good to me. I just so happen to have started a log a few minutes ago in the Grow Diaries section using an 8-bulb T5 Sunleaves unit. I've grown with it before and had good results. I've also grown with 400-800 watts of HPS. The difference that everyone speaks of concerning yield is a real difference when both systems are compared growing plants in a natural vertical fashion. However, your not using them as a stand-alone lighting source, but instead as side-lighting, so I say hell yeah man! Fluoros are great for supplemental light. I say go for it, you'll get your money's worth. Especially since the same basic amount of heat is produced both ways, but with the floros, the heat is spread evenly along the length of each bulb. To me, it makes the plants a little less succeptable to heat stress.

As far as people spouting off about floros producing most of their light in the green section of the color spectrum.....I say they are either hating on floros or used inferior bulbs. My Vitalume tubes are 12USD each....cheap enough, yet still name brand tubes.

Let us know what you decide to do.

 

[Dr. Katz]

I use a T5 for my veg room and am very happy with it, though it's the blue spectrum, not the 3000K. I have also smoked buds that were flowered under an 8-bulb (four foot bulbs) T5, that had 6 orange bulbs and 2 blue ones. If my buddy didn't tell me, I wouldn't have known that they weren't from an HPS. I say go for it, especially if you grow tall plants that don't get too much light on the lower buds.

 

[jawnroot]

Excellent. I'm pretty much locked in on the T5's, as they seem about perfect for the supplemental lighting I need. One question...how close can the plants get to the tubes? With the way they'll be mounted, some leaves might get pretty darn close.

Also, do you think a small T5 fixture with the grow bulbs (probably a 24" fixture with two HO bulbs) would be enough to take a seedling from start to around about 6"? Perhaps supplemented with a few small T8s on the side?

 

[ProGroWannabe]

Q#1...As long as the leaves don't literally touch the bulbs, you shouldn't have any issues. In my 8-tube, I can't run em quite that close when they're young, because I can't get the fan underneath the unit since the space is so small. So I run mine as low as I can get it with the fan underneath it. With "Grow" tubes maybe Dr.Katz can give better advice as all I've ran in mine are the "Bloom" tubes.

Q#2...In my opinion, it would definitely be enough. Your on the right track though, much taller than 6 inches and you'll need more intensity than the two bulb will afford....again, just my opinion.

 

[jawnroot]

ProGro: Thanks for the help, much appreciated. Originally, I was just going to veg them with the 150 HPS, with a few small T8's as supplemental, but after I thought about it, I figured the T5 would be far superior to a vert HPS for veg, green spectrum or not.

These are going to be 12/12 from seed, so they're only staying under the veg light until they sex (2-3 weeks), after which time they'll probably be about 6 inches, maybe less.

From your post, it seems like you use the "bloom" bulbs for young plants. How did this work for you? Get any appreciable stretch? Given that these are going 12/12 from seed, it might be beneficial for me to stick them directly under the bloom bulbs, and maybe have 5500K or so T8's along the side for the supplemental blue. Any thoughts on this?

What would you say is a good distance to mount the light above seedlings? I've heard anywhere from 2" to 8", and everything in between.

Thanks in advance, and sorry for all the questions.

 

[Dr. Katz]

The leaves can be within an inch or two of the T5's without getting burnt in my experience. Even once they're touching the bulb, it takes 2 or 3 days to actually see any burn marks. As far as I know, the main disadvantage of the T5's is that the light intensity goes down more as you get farther from the light, when compared to an hps. So to take advantage of what you've got, get your plant tops as close to the light as possible, leaving maybe 2 inches so they have a little room to grow. As far as using the smaller T5 grow bulbs for vegging small plants, that should be fine. Just remember that the area that will get good light is pretty much the same size as the fixture, so I would say that the 2 foot, 4 bulb setup would be good to veg at least 6-8 seedlings in 16 oz beer cups, maybe up to 12 if you pack them in.

 

[jawnroot]

Dr. Katz, many thanks. I intend to veg only 8 of them until sex, as I'm looking for just two good females for my space. Once they show sex, I'm going to introduce the HPS, then (within a week or so) choose the best looking two to finish out.

 

[spinkus]

Jawnroot I use a 400w T-5 for veg and love it I get just as many cuttings, if not more than my MH and it keeps the height managable and the heat down. Just for a idea on what Dr. katz was talking about with the leaves touching here my T-5 in veg.