T8 vs T5 HO vs (maybe) LED?

[bower]

LED's are way lighter than T8's too FWIW. Much easier for me to move them around from one setup to another. They are light and have a low profile - the T8 fluorescent has that big ballast hidden in the hood.
IMO though the plants really love that 6500 K wavelength even though they are okay with the 4000K LED I got.... I will be more patient next time and find an LED with the 6500 K which I believe is best for what I'm doing - greens and seedlings.

[Ricky Shaw]

If you already have T-8 fixtures. These would also help those with issues of trying to keep temps lower when cold treating seedlings. Still, I'd like to see the price come down even if they do last 45 years.


Home Depot

Philips
4 ft. T8 22.5-Watt Daylight (6500K) Linear LED Light Bulb

https://www.homedepot.com/p/Philips-...7211/204677351

[FourOaks]

Originally Posted by bower

LED's are way lighter than T8's too FWIW. Much easier for me to move them around from one setup to another. They are light and have a low profile - the T8 fluorescent has that big ballast hidden in the hood.
IMO though the plants really love that 6500 K wavelength even though they are okay with the 4000K LED I got.... I will be more patient next time and find an LED with the 6500 K which I believe is best for what I'm doing - greens and seedlings.

The pictures you posted are proof positive, thats for sure.

Originally Posted by Ricky Shaw

If you already have T-8 fixtures. These would also help those with issues of trying to keep temps lower when cold treating seedlings. Still, I'd like to see the price come down even if they do last 45 years.


Home Depot

Philips
4 ft. T8 22.5-Watt Daylight (6500K) Linear LED Light Bulb

https://www.homedepot.com/p/Philips-...7211/204677351

$70 per bulb. Ouch..

[Tiny Tim]

FourOak, 1000 watt draw at the wall LED will likely out preform any 1000 watt HID with the exception of maybe a Ceramic Metal Halide. I will be experimenting with a small 315 watt CMH next myself. Every manufacture wants our money and many are willing to twist the truth a bit to get it. I'll trust doing actual side by side comparisons myself. Remember the larger LED will weigh more than a hood and bulb of your HID lighting. Unless your running a one piece ballast/hood combination. Like most CMH are set up. Most digital ballast and old reliable magnetic ballasts are remote from your hood.

[bower]

Originally Posted by decherdt

I missed out on the whole T12 - T8 generation.
I've used a Kill-a-watt and a photometer app on my Pixel to check what systems I have. T5 and LED floods. <--these LED are not what I hoped. d'oh.
I prefer the results of the 12000 lux T5 over the 35000 lux LED flood.


Left
T5 12000 lux

Right
LED Flood 35000 lux

I just went back and took a second look at this... thanks for posting the pic!
Some of my tomato seedlings got switched to the LED after potting up.. and some of those are looking very distressed. None of the seedlings under T8 are showing the same stress. So I am having second thoughts about whether a simple LED shoplight is fine for tomatoes. Maybe just the combination of transplant stress + ??? I could say higher lumens but the light is raised higher to compensate for that. Hard to tease the causes apart, they would be colder because less heat from the lights, spectrum at 4000 K is different, add water to that.. etc.

[FourOaks]

Originally Posted by bower

I just went back and took a second look at this... thanks for posting the pic!
Some of my tomato seedlings got switched to the LED after potting up.. and some of those are looking very distressed. None of the seedlings under T8 are showing the same stress. So I am having second thoughts about whether a simple LED shoplight is fine for tomatoes. Maybe just the combination of transplant stress + ??? I could say higher lumens but the light is raised higher to compensate for that. Hard to tease the causes apart, they would be colder because less heat from the lights, spectrum at 4000 K is different, add water to that.. etc.

Im just guessing that the wave length is incorrect. Im thinking that to get in LEDs, you have to bite the bullet and spend the moolah to get the real deal.

[bower]

Originally Posted by FourOaks

Im just guessing that the wave length is incorrect. Im thinking that to get in LEDs, you have to bite the bullet and spend the moolah to get the real deal.

There's something not right about it, for sure. We saw the scorching before on brassicas, but they were great once they got used to it. But different plants have different sensitivities and needs. Would like to see how others have done with tomato seedlings under a shop-light type LED.

[Tiny Tim]

bower, I'm seeing the same poor results with my new shop light LED. It's NOT the same as my full spectrum LED's. Maybe the plants just need more time to adjust, or I'm expecting to much from a 40 watt fixture.Like you mentioned, mine is also in a cooler room and it puts out very little heat.

[Greatgardens]

Originally Posted by Ricky Shaw

If you already have T-8 fixtures. These would also help those with issues of trying to keep temps lower when cold treating seedlings. Still, I'd like to see the price come down even if they do last 45 years.


Home Depot

Philips
4 ft. T8 22.5-Watt Daylight (6500K) Linear LED Light Bulb

https://www.homedepot.com/p/Philips-...7211/204677351

I was intrigued by this link. I was in HD last week, looking at their selection of LED's. They had in-stock Philips led replacement tubes for T8 and T12 fixtures. They were apx. $7.50 each. The only hiccup was that these were designed to use the existing ballasts, and only were listed to work with certain ballasts. Everyone goes into the HD store and knows their ballast number, right? ,

I'm not certain if the other details, but certainly not $68 -EACH-.

GG

Edit: I think this is what I saw from Philips at HD:
https://www.prolighting.com/ph-45657...RoCsXcQAvD_BwE

That's quite a link...

[FourOaks]

Maybe an interesting experiment.


Because the "shop leds" are so dang expensive, theres another route. Perhaps the ""screw-in" type flood light? I have glanced at those on Amazon. Something like this:


https://www.amazon.com/Morsen-Greenh...led+grow+light


So maybe a side by side with one of those, and a plain led spotlight. I happen to have one on the side of my house. Its crazy bright, I dont know the specifics, but it could be the placebo.

[oakley]

I'm not having the issues some are having. Certainly not like some of the youTube
videos. Most are just not doing precise 'controls'. Not good enough for me any who.

I had a bit of burn under the full spectrum but those three plants are dwarf project
plants at about 2 ft tall now, not starts. (they also spent a few days in a sunny window)
NOT a controlled study.

Under my LED shop lights....top pic end of January, and last week some of the micros
potted up.

[oakley]

And micro greens I've been growing all winter. I grow much longer and more
into the baby green stage.

[FourOaks]

Oakley.. would you care to share the exact lights that you are using? If you already pointed this out, I missed it.

[bower]

Originally Posted by Tiny Tim

bower, I'm seeing the same poor results with my new shop light LED. It's NOT the same as my full spectrum LED's. Maybe the plants just need more time to adjust, or I'm expecting to much from a 40 watt fixture.Like you mentioned, mine is also in a cooler room and it puts out very little heat.

Well this morning I decided to get to the bottom of it. Took pics, took off leaves checked undersides, didn't find an insect cause so I did a google for tomato leaf edema (the term "intumescence" is also applied to this physiological condition) and guess what. Light spectrum issues came up right away.

https://ag.umass.edu/greenhouse-flor...-intumescences

"..Recent research indicates that light quality, specifically ultraviolet-B (UVB) radiation is directly related to preventing or minimizing intumescence symptoms on ornamental sweet potato and tomato,.."

http://hortsci.ashspublications.org/...6/712.abstract
Far-red and Blue Light Synergistically Mitigate Intumescence Injury of Tomato Plants Grown Under Ultraviolet-deficit Light Environment
Yes, the text refers specifically to LEDs

Attached below, a graphic of research results from:
http://msue.anr.msu.edu/news/does_li...pment_of_edema

And pics of the edema on my tomato leaves. One interesting thing, they say susceptibility varies by cultivar and for me, there were more-less-and not affected plants in each group of F3, F4 etc so I could make this a point to select away from that susceptibility.
I'm satisfied that the LED shoplights are good enough for greens. I could probably make them usable for tomatoes by hanging the light in one of my window spaces, so they get natural light as well. Will have to look at my plant shuffle options and decide what to do...

[Greatgardens]

Really interesting links!
GG