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Name: Yardenman
Maryland (Zone 7a)
Feb 10, 2021 12:58 AM CST
Years ago, I bought a 4'x2' steel 4-shelve stand and added fluorescent fixtures and added 4 bulb T-8 fixtures (I regret that because they are narrow) and dual 2 bulb T-12 (better because they are further apart). But the bulbs only last a year at 14 hours a day for a few months in spite of the promises of "20,000 hour" lifespan.

I'm SO tired of finding a bulb burned out and needs replacement every week or so. I'm curious about LEDs and I DON'T mean the weaker tube types. I'm curious about real multi-Led fixtures. I would be happy to remove all the shelves and change fixtures.

So, I'm thinking of changing to LED fixtures, but am not sure what to get. I can understand lumens, K, and watts. I think want about 2800 lumens, 4500-6000K, and I understand that LED watts are not the same as fluorescent watts. My 3 14 W LEDs in the ceiling lamp produce more lumens than 3 60 W incandescents for example and I understand why. I'm good with that.

What I can't seem to find about the LEDs is the color temperature/spectrum/K and how many I need per fixture. Can you tell me the equivalent number of some wattage LED 5000K bulb fixture that is like my existing 4 40 watt tube 5,000K T-12s? Or give a link to a technical site? I can't seem to find one.

This isn't a cost or "what lighting you prefer" question. It's a "what technically equals what I have" question. Though "better" would be OK... ;)
Name: Big Bill
Livonia, Michigan (Zone 6a)
Professional Geezer
Region: United States of America Critters Allowed Growing under artificial light Echinacea Hostas Region: Michigan
Butterflies Lover of wildlife (Raccoon badge) Orchids Cat Lover Birds Bee Lover
Feb 10, 2021 5:46 AM CST
I am using T-5's, I believe they are 6,500k and they are doing wonderfully well after 28 months now.
According to my light meter and the response seen by my orchids, they have maintained the same intensity with very little reduction.
They are cheap to run and I have 12 tubes going. I estimate my monthly cost per bulb is less then a dollar!
Rodney Wilcox Jones, my idol!
Businessman, Orchid grower, hybridizer, lived to 107!
Lockhart, Texas (Zone 8b)
Hydroponics Greenhouse Region: Texas
Feb 10, 2021 9:05 AM CST
Forget lumens. It's a human vision reference and not of much use with plants. But the actual useful measure for growing is not something you can directly measure without quite expensive equipment. However, the is a rough rule for LED grow lights. That is about 32 watts per square foot of plant area.

Now that sounds simple, but there are some things you have to know to avoid wasting money. One is the makers are fond of displaying their "watts" in large print, when what they mean is some imagined equivalent to incandescent lights. The rule above refers to actual LED consumption. Often in ads, that number isn't even given. It's the rating that appears on the plate on power products. There can be a 10X difference between the two. Grows lights is right up there with honey and olive oil on my list of most crooked selling. You want to look at actual consumed watts.

The bottom line on that is that there are no great bargains. You get what you pay for. If you think you're getting 150 watts for $30, you're being tricked, and you are actually getting more like 20 or 30 watts. If you think you get 300 watts for $60, look at this product.

300 Watts in the description. But look way down in the specs, and see that it's really 65 watts. That's a big difference in coverage. Some ads at least show the lights being reasonable used. In that one, they do show it lighting a 10'"x20" tray. Two square feet. That's about right at low mounting height. It won't do the eight or ten square feet you'd expect from 300 watts. Not even close.

You will also see that the light itself is about two square feet. But the beam width is not given. But from the design, it's apparent that a lot of the light falls outside the two square feet. That's not fatal, but it does waste power.

You will see "full spectrum" touted. Who knows what that means? Maybe they mean it's like sunlight. Or a light may have a mix of blue and purple LEDs (blurple). Don't worry about that stuff right now. There's a lot of baloney in the ads that they can arm wave away. But there's no real great virtue in emulating sunlight. Plants have very limited use for a lot of the natural sunlight spectrum, so some part of the power is going down the drain.

Let's say you will grow in the one foot wide strip down the middle of each of your 2'x4' shelves. Four square feet. You want 120 to 150 actual consumed watts of LED lights. You could just get my with two of those products above. $130 per shelf for lights. And that's not bad for appropriate lighting. I fully lit three 2'x4' shelves with commercial LED strip grow lights from Illumitex. They were about $1,000 new and were about 170 watts per shelf. Four shelves, fully lit, will run $600 to $1,000, and you're not going to do it right for much less. LED's are a world commodity, so every maker pays market prices.

It's useful, too, to use a configuration that lets you easily raise and lower the lights. When you're working close to the lower limit of adequate light, you need to start low and raise the lights as the plant grows. It's easier to do with some than others.

You can consider fluorescent grow lights, but remember that the rule then becomes about 100 watts per square foot. (That's how the LED seller trick you, by quoting you the equivalent for fluorescent and hoping you won't notice.) A four-foot T5 fluorescent grow light tube will consume about 54 watts. Four of them will light you shelf.
Name: Steve
Port Orchard, WA (Zone 8b)
Feb 10, 2021 1:33 PM CST
IntheHotofTexas, agree with most of your post. But fluorescent bulbs and other lights use more current during start up that when on. Fluorescent bulbs need power to initially ironize the bulb.
I use 2 LED bulbs that replaced 60 watt incandescent bulbs, for my overwintering grow station.
BigBill, I do not grow orchids anymore, but realize they are fussy (only grew cymbidiums successfully).
Yardenman, I agree with Gerald that you should raise and lower LED lights as needed.
Name: Valerie
Ontario, Canada (Zone 4b)
Region: Canadian Seller of Garden Stuff Peonies Hybridizer Irises Daylilies
Plant and/or Seed Trader
Feb 19, 2021 12:59 PM CST
Ignoring the technical jargon - there was a small study done by the RHS many years ago that showed there was very little advantage in buying any type of bulb designed for plants. I still use ordinary 4 foot fluorescent tubes in my Light Garden (two for each of the 3 shelves) and while they do consume more hydro than the T8's etc they also put out heat, which I take advantage of by putting seed trays on top of the light canopies for seeds that need bottom heat to germinate. We have time-of-use hydro rates so at night (cheapest) I have the lights on and during the day they are off and benefit a little from daylight.
Name: Yardenman
Maryland (Zone 7a)
Feb 23, 2021 7:01 AM CST
First, I'm looking for a simple plug-in ceiling-type fixture that will accept 6-10 screw-in bulbs.

Second, I don't lower the lights. I built "glued and screwed" plywood platforms of varying heights to raise and lower the plant trays as needed. I also have the light stand shelves set at 8", 12", and 16" which offers a variety of heights.

Third, what LED screw-in bulbs meet 5000-6500 Kelvin?

[Last edited by Yardenman - Feb 23, 2021 7:03 AM (+)]
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Name: Steve
Port Orchard, WA (Zone 8b)
Feb 23, 2021 7:18 PM CST
Yardenman, I googled "kelvin light spectrum" . It appears to answer your question in the post "understanding kelvin and LED light color temperatures--posted by LED light expert. Appears you are looking for a Cool White or 5700 K LED. As far as your question on how many to replace existing bulbs, my GUESS is having a string of LEDs equal to the length of your 3 T12s--just a guess.
Hope this helps you.
[Last edited by BrooklynStart - Feb 23, 2021 7:33 PM (+)]
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