T8 vs T5 HO vs (maybe) LED?

[FourOaks]

What kind of radius do the leds cover?


This topic has got me really considering leds to some degree. We have had so many gray days that my plants are really starting to suffer out in the greenhouses. Im thinking some kind of supplemental lighting in the future might be necessary.

[Tiny Tim]

Al@NC I do run larger LED's. My Mars 300 watt I keep 12" from tops. My Mars II 400 watt I keep at about 24 inches for seedlings. It's the light spectrum that burns the plant not the heat with LED's. I've just never run this low watt strip type of LED. Thanks bower. this is a 5000k. I have it at about 8" and it has burnt the tips of my onions Other then that, the tomato's, peppers and eggplants look ok.

[Al@NC]

Originally Posted by Tiny Tim

It's the light spectrum that burns the plant not the heat with LED's. I've just never run this low watt strip type of LED.

Yeah, the LED I have doesn't put off any heat hardly, I was thinking the same thing..

Al

[oakley]

Originally Posted by bower

4500 lumens is a lot compared to the typical fluorescent, iirc my 6500 k comes in at 3750 lumens for the pair. The LED lights I bought this year are 4000 lumens. I did have some ?? scorchy leaves ?? on certain brassicas under the LED but don't know for sure if that was the cause.

If it was me, I think I'd set up at least 8 inches to a foot above the seedlings, and wait to see the effects. If they're stretching to get closer, bring it down. But I'm only guessing.

Not a bad guess. I'm thinking some minor scorching is what happened here. Not on
the thick rugosas micro toms, but some of my micro sunflowers jumped up a bit
beyond micro and have some burn. I'm keeping all starts at 5-7inch, not 2-4.

[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

[FourOaks]

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

Very interesting data you have there, with pics to back up. Thanks for posting. Im curious, did you take measurements of how close the lights were to the flats? Or could you take a guess as to the distance?

[decherdt]

Originally Posted by FourOaks

....did you take measurements of how close the lights were to the flats? Or could you take a guess as to the distance?

About 1 to 2 inches above the plants. Maybe too close for the flood light.
Had seen this http://www.tomatoville.com/showthrea...758#post534758 and got a few to fiddle with, but I may be done with flood light, no real need to reinvent the LED

[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.

[Ricky Shaw]

Unless the warmth of HPS benefits you, or you're trying to cover a large area, they're overkill. Seedlings just don't require that much light. T12's in simple daylight bulbs (6500k) have turned out beautiful trays of seedlings for years.

[FourOaks]

Originally Posted by Tiny Tim

FourOaks, as Bower mentioned LED won't take extreme heat. Most folks that have diodes burn out don't run an air exchange system. That's why I always run cool air intake and exhaust in my situation. I know the manufacture I use will send you free diodes if you have any burn out. I'm going on 2 years and not one bad diode yet. HID, HPS and MH are old school lighting. They do work. But, you'll pay to run them. I run a cheap batwing hood because I just wanted to run a 1 plant comparison. The light will be gifted to a friend soon.

Have you looked into CMH by any chance. It may give you the best of both worlds for your greenhouse.

Happy gardening..

Tim... do you know of any comparison charts that involve LED vs. HID lighting? I havent looked that hard. But I do know that no matter what, 1000 watts is 1000 watts.

Never heard of CMH.

Originally Posted by Ricky Shaw

Unless the warmth of HPS benefits you, or you're trying to cover a large area, they're overkill. Seedlings just don't require that much light. T12's in simple daylight bulbs (6500k) have turned out beautiful trays of seedlings for years.

Ricky... in this case yes.

You may have missed whats going on. My seedling operation is expanding, and im combating cold gray days out in the greenhouses. So, in this instance, the heat and power of HID lighting would be beneficial.

I currently use T8s, am at the point to switch to T5s, LED, or HID.


And Greatgardens, once again, sorry to highjack your thread. You havent chimed in, so it would be interesting to see what your opinion is.

[Ricky Shaw]

Yes I kind of picked up it was of benefit to you Four Oaks, sorry I should have been more specific. AKmark and Cole Robbie use them in much the same way, for warmth and to cover larger areas than a grower at home in heated spaces. More of just a general comment that in a lot of cases, unnecessary.

[FourOaks]

Originally Posted by Ricky Shaw

Yes I kind of picked up it was of benefit to you Four Oaks, sorry I should have been more specific. AKmark and Cole Robbie use them in much the same way, for warmth and to cover larger areas than a grower at home in heated spaces. More of just a general comment that in a lot of cases, unnecessary.

Its all good, friend.


I didnt intend to hijack this thread, but see it as pointless to start a new thread, with virtually the same discussion. And your right, for most folks at home, t12s thru t8 do just dandy. Years ago I started with t12s. In 2015 upgraded to t8s. Now its time for another upgrade. And choices, choices, galore.


And honestly, I really dont know which direction to go.

[bower]

This thread is really interesting even if it went a bit further than the original topic. The OP can always chime in again, if we've totally missed the point.
Speaking of point, there's one more difference I noticed and should mention: length of warranty on the lights. I know my original T8 fixtures had only a one year warranty. Yes they were bottom of the line, basic shoplight, with some defects I had to take care of myself when I figured it out (Those pull-down configured sockets suck, for not holding your tubes snugly and firmly in place). But I think 1-2 years is a typical warranty for fluorescent fixtures. The LED fixtures OTOH nearly all come with a five year warranty. That is pretty good for fixture plus lights included.