LED fixture ?
 

I am liking to replace some of my 4 foot Fluorescent fixtures with LEDs. My primary reason is heat. I built several 48”x 18” racks six feet high for my seed starting, so I need to replace the fluorescent fixtures with something similar.

What I am looking for specifically is a LED fixture whose coverage is an area of approximately 18”x 48” and something like 10,000 lumens. These hang about 4-6” above the seedlings so The 10,000 lumens is the area I need.

Most of the LED fixtures seem to be much more powerful and are designed to hang much higher than 4-6”. I do not have the airspace to hang the fixtures much higher than I already do. What type of fixtures am I looking for?

LED Grow Lights
 

I have had good success with these using 2x per 48" rack in multiple tiers. Easy to adjust height but the transformer gets quite warm. No problems after one season of use when on 14 hours per day, 7 days a week.

LED Grow Light for Indoor Plants,YGROW Upgraded 75W Growing Lamp Light Bulbs with Exclusive Full Spectrum for Greenhouse Vegetables Plants from Seeding to Harvest.

[url]https://www.amazon.com/gp/product/B07CYXT8R1/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1[/url]

walmart has the replacement led grow light bulbs that go into the old t8 fixtures.

Thank for the info. I am a little concerned that the light you posted a link for says the recommended height is 11 to 23 inches. I am looking for something that can be hung more like 4-8” above the seedlings, just like fluorescent fixtures. I don’t have the vertical space for 11-23”.

Billim: I have mine set up so that initially the fixtures are ~2" - 3" above the seedlings and progressively raise the fixture as the seedlings grow keeping it 4" - 5" above the plants when they are 4" tall as I prune them back. Hope this helps. BTW, the fixtures/LEDs are not hot so no chance of burning the plants. I use them for all of my seedlings (peppers, tomatoes, okra, squash, cukes, etc.)

Take a look at these. I just purchased my second set of these for this years season. I have used a set for the past two years and have great results with pepper and tomato seedlings. I too just built a rack and now have two shelves for seedlings to grow on. That is why I know have two sets of lights.

I keep them within a couple inches of my plants.

[url]https://www.amazon.com/gp/product/B07XQDP5X9/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1[/url]

Glad you posted this, because it got me browsing for what is now available - since I last looked, the 'sunlike' full spectrum has become a happening thing, and nice price for packs of four X 42 watt 4 ft fixtures.
I reckon if the wattage is the same and the spectrum is balanced it should make a perfect replacement for the old fluorescents on the same sized shelf. Don't know if higher wattage means you should keep them further from the plants - there are 64W 4 fts available too, but they are pricier and sold by each. I seem to remember the fluorescents were 32 or 42 watts? And that was enough for the seedlings to do fine...

Anyway this will be my next light purchase. I can't look at the pink ones they are nauseating to me and I don't get jazzed by the looks of the plants under them either.
[URL]https://www.amazon.com/dp/B07ZYTBQ15/ref=twister_B08354RRNP?_encoding=UTF8&psc=1[/URL]


Just wanted to add that I am not 100% happy with the LED shoplights in a single frequency 6500 K. Had some strange seedling reactions to them, although brassicas and lettuce seem fine, tomato and pepper seedlings didn't do well under them.

[QUOTE=bower;753043]Glad you posted this, because it got me browsing for what is now available - since I last looked, the 'sunlike' full spectrum has become a happening thing, and nice price for packs of four X 42 watt 4 ft fixtures.
I reckon if the wattage is the same and the spectrum is balanced it should make a perfect replacement for the old fluorescents on the same sized shelf. Don't know if higher wattage means you should keep them further from the plants - there are 64W 4 fts available too, but they are pricier and sold by each. I seem to remember the fluorescents were 32 or 42 watts? And that was enough for the seedlings to do fine...

Anyway this will be my next light purchase. I can't look at the pink ones they are nauseating to me and I don't get jazzed by the looks of the plants under them either.
[URL]https://www.amazon.com/dp/B07ZYTBQ15/ref=twister_B08354RRNP?_encoding=UTF8&psc=1[/URL]


Just wanted to add that I am not 100% happy with the LED shoplights in a single frequency 6500 K. Had some strange seedling reactions to them, although brassicas and lettuce seem fine, tomato and pepper seedlings didn't do well under them.[/QUOTE]
What kinda problems did you have with the shop lights?

[QUOTE=biscuitridge;753047]What kinda problems did you have with the shop lights?[/QUOTE]


Tomatoes turned purple and got edema. Peppers were just stunted.
There's another thread here where I did some searches about that problem, and the science described the same thing and explained it. Absence of far red and blue frequencies can have weird effects on tomatoes.


Here I found it. Good discussion involving people trying out different lights. I was pretty happy with the greens under 4000K LED shoplight earlier in the thread.. Then I put tomato seedlings under them:
[url]http://www.tomatoville.com/showthread.php?t=46760&page=4[/url]
Not all of the old links work, but basic info about "intumescence" (same as edema but different cause) "[I]While edema is considered to be the result of an imbalance in water relations within a plant, intumescence is associated with low ultraviolet-B (UVB) radiation[/I]."
[url]https://ag.umass.edu/greenhouse-floriculture/fact-sheets/edema-intumescence[/url]
And this research:
"https://www.canr.msu.edu/news/does_light_quality_impact_the_development_of_edema"


Note that my shoplight is 4000K, others had good results with LED 6500 K. The safe way to go is to get a light designed to provide broader spectrum. But blue light/UV end is most important (afaict more important than the far red) for tomatoes and other plants sensitive to lack of the blues.

Phillips has LED Instafit bulbs for both T8 and T12 fixtures. Maybe they would be a possible option.

[QUOTE=Billm302;749568]I am liking to replace some of my 4 foot Fluorescent fixtures with LEDs. My primary reason is heat. I built several 48”x 18” racks six feet high for my seed starting, so I need to replace the fluorescent fixtures with something similar.

What I am looking for specifically is a LED fixture whose coverage is an area of approximately 18”x 48” and something like 10,000 lumens. These hang about 4-6” above the seedlings so The 10,000 lumens is the area I need.

Most of the LED fixtures seem to be much more powerful and are designed to hang much higher than 4-6”. I do not have the airspace to hang the fixtures much higher than I already do. What type of fixtures am I looking for?[/QUOTE]

Do you want to use it to start seedling and get them ready to plant outside or take plants all the way through maturity. I have had good luck with some inexpensive LED shop lights. I started with the 4' LED shop lights from Costco, but found some cheaper and much better on Amazon. They put out much more light than those from Costco. Three of the fixtures cost $60 and put out 14,400 lumens at 5000k. (They actually sell 6 for $120) I don't know what type of life they have or how long they will maintain their brightness. Mine are about a year old now and doing fine. [url]https://www.amazon.com/gp/product/B0789HRZR9/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&psc=1[/url]

I put three fixtures across a 4' shelf. I can get three rows of lights on a single 72" X 48" X 18" shelf. You might be able to get away with two per shelf for starting seedlings. The lights sit on top of the edge shelf brackets and the two middle shelves I set on top of the three lights below.That leaves about 15-20" or so between the shelf and the light above. I use pieces of foam board under the trays of light to keep the plants 1-3" below the lights themselves. The closer to the light you can keep them the better. They are cool enough that even if the plants grow to touch the lights, for a short time it doesn't damage them.

I take micros from start to finish under the lights and they do fine.

I hadn't looked through all the links mentioned above. Perhaps the actual grow lights mentioned above may do better. I'm not sure. Perhaps I'll try some to see. The shop lights have worked well for me.