Grow Lights

[zendog]

By the way, these are the one’s I’m putting in. I had previously used frosted casings on the ones I used on the fish tanks, but for the plants I went with clear to hopefully get the most light to the plants. We’ll see how it works.

Barrina T8 T10 T12 LED Light Tube, 4FT, 22W, 6000K (Super Bright White), 2600 Lumens, Dual-End Powered, Clear Cover, T8 T10 T12 Fluorescent Light Bulbs Replacement, 8-Pack - - Amazon.com

[aap]

I don’t use my lights for growing, just keeping my tree’s alive during the colder days. My citrus and subtropicals have all led’s shoplights bought from Sam’s club.
So far they like them just as well as the t-8’s. Bought these guys on sale for $24.00. Room temps stays at 65*.

[forestandfarm]

Zendog, That is what I was the information I was looking for. And thanks for posting that link for the bulbs you are using as well.

Derek, No, Lumens/Watt is a measure of power efficiency. No doubt LEDs are more power efficient. I was looking for how much heat is produced by the unit and received at the plant.

The amount of light energy the plant has to use is a function of intensity and duration of light received by the plant. I can’t duplicate the intensity of the summer sun, but I can run long days. My trees do need a rest period and I’ve found 15 hour days give them enough dark rest period. The more intensity of light received at the tree, the more that can be converted into plant energy. This also means I don’t have to acclimate them to the sun quite as slowly. Since the light energy diminishes with the distance from the plants squared, I want the lights positioned as close to the trees as possible without the heat from the bulb/fixture having a negative impact on the tree.

[forestandfarm]

Another thing I think I like about those bulbs over fluorescent is that it appears from looking at your link, all of the light is produced on the under side of the bulb. Fluorescents produce the light in 360 degrees so half of it needs to be reflected by the fixture which significantly reduces intensity.

Am I looking at those pictures correctly?

[zendog]

Am I looking at those pictures correctly?

Yes, that is correct.

If I hadn’t already bought the replacement bulb types, I actually might consider getting something like these instead:

Brillihood T5 Integrated LED Single Light Fixture, 4FT, 2200lm, 6000K (Bright White) Clear Cover, 20W Utility Shop Light, Kitchen, Ceiling and Under Cabinet Light Tube with ON/Off Switch (10-Pack) - - Amazon.com

With these single strip LED fixtures, I could space them out evenly across my growing area. Using my existing 2-bulb shop lights mean that the bulbs will be together in pairs, instead of spread out evenly, so I suspect the lighting will be less even since the LEDs will be more directional than the diffuse light of the fluorescents.

[forestandfarm]

I’m using very inexpensive fixtures so they don’t have a wide reflector. I hang them close enough to each other that there is not a huge difference in bulb spacing. The reason I like the replacement bulbs verses the strips is for rigging. Those strips are daisy chained with short cords. It sort of makes them in to a single fixture because of the interconnection.

My current fixtures are on cords attached by prussic knots that I can slide easily to reposition each fixture. My rootmaker Express tray 18s let me reorganize cells. I organize 3 rows across two trays (about 4’) from tall to short. I can then angle a single fixture accordingly. I then do the same with the next 3 rows for the next fixture.

With the first link you posted, I can keep my existing rigging that works well for me and save time. However, I can certainly understand how folks with somewhat different applications that I have may benefit from the strips in the second link.

[TheDerek]

indoors 100% off the electricity used by lights is turned into heat. some lights produce heat directly as essentially a waste product, others produce more radiation (light) which doesn’t turn into heat until it hits something. 600w of led produces as much heat as a 600w traditional bulb would, it just produces a lot more light in the process.

[forestandfarm]

Ok, but…once again you are addressing only the transmitter, not the receiver, and not all heat is the same. My primary concern is not how much of the power consumed is turned into heat. My concern is how much of the energy transmitted by the light is used by the plant for photosynthesis. Photosynthesis is the process of converting radiant energy into chemical energy for use in the plant.

This radiant energy diminishes by the distance squared. When a light emits a lot of convective heat, it needs to be kept far enough from the pant that the convective heat does not have a negative impact on the plant. Humidity and other things come into play, but in general, if you put a light that produces a lot of convective heat too close to a seedling, it will dry out and die.

So, when zendog does the “touch test”, it is a good proxy for the amount of convective heat that is produced (even though he is actually estimating conduction). It is good enough for my purposes so that I know I’ll be able to hang the lights with similar proximity.

Since we all know that LED lights are generally more power efficient (more lumens/watt), we get the side benefit of lower energy consumption over all, meaning less total heat (energy), with roughly the same lumens produced. I simply wanted to verify that these tubes would not need to be kept further away. I know when I replaced some can flood lights with LEDs, while they were not even close to the heat of the incandescent floods, when unscrewing an LED that had been on for a while, I was surprised how warm the unit was. I presume it was an inefficiency in the conversion in those early lights.

Not disagreeing with your statement, simply trying to make clear for folks what is important in my application and why I was asking.

[TheDerek]

ok i get what u r saying. strip led light will run cooler than fluorescents usually. the ones i use for growing are hardly warm to the touch. you’ll have issues sooner with to much light for your plants than to much heat. i would look for some that are daylight or warm white instead of cool if thats possible to find.

[forestandfarm]

I’d love to have that problem, but I don’t think I can compete with the summer sun in terms of radiant energy. I played with the color rating years ago and it had zero impact on my tree. It is a tiny percentage of their lives spent indoors under lights and a single stage of growth. I found it was much more economical to buy a larger box of 6000K than buy individual bulbs of different color ratings. This may not be true of other indoor growing applications but it certainly is for starting trees in root pruning containers in the winter.

[danzeb]

Use of LED in horticulture is increasing.
https://www.ledsmagazine.com/articles/print/volume-12/issue-3/features/life-science/led-technology-serves-rapidly-growing-horticultural-market.html

[zendog]

Zendog, That is what I was the information I was looking for. And thanks for posting that link for the bulbs you are using as well.

I just wanted to follow up and say that the testing I did was with slightly different bulbs I had purchased and am using over the fish tanks. The one’s I linked to I bought but haven’t begun using yet, so I can’t be sure if they’ll be a little hotter or not, but they are a few more watts (22 I think instead of 20 in the ones I have running now) so they might be a bit hotter. Still, I don’t think it would be enough to have it be a problem.

[TheDerek]

Heres a good DIY guide to build a LED light for those interested…

[forestandfarm]

I really like to inexpensive shop light fixtures for starting trees indoors in the winter in root pruning containers. Using cords and prussic knots I could easily organize my seedlings by height and angle the fixtures individually to keep the cool fluorescent bulbs just a few inches from the seedlings.

I finally ran out of fluorescent bulbs last week and decided to order LED replacement bulbs. After reading this thread and doing some other digging this is what I ended up with: https://www.amazon.com/JESLED-Dual-Row-Fluorescent-Equivalent-Daylight/dp/B079GXFTHQ/ref=sr_1_8?s=hi&ie=UTF8&qid=1550883577&sr=1-8&refinements=p_n_feature_five_browse-bin%3A6104138011%2Cp_n_feature_nineteen_browse-bin%3A9692451011%2Cp_n_feature_eight_browse-bin%3A9692458011%2Cp_n_feature_seventeen_browse-bin%3A9692445011&th=1

It was a very easy conversion. My fixtures had an electronic ballast so a few wirenuts and one short piece of jumper wire (about the length of the ballast) was all that was needed to convert them to ballast bypassed dual end powered.

I’m very happy with the result. The LED bulbs are significantly lighter weight than the fluorescent bulbs. I’d estimate they are about 40% brighter. Some of that comes from the higher lumen rating, but unlike fluorescent bulbs these are directional. Fluorescent bulbs put out the light equally in 360 degrees. This means half of the output must be reflected off the fixture before it hits the plants. That issue is gone with these bulbs.

I still have all the same adjustability of the existing fixtures and the same form factor with more light output and lower long-term operating cost.

[zendog]

Looks like some great bulbs for a good price. Let us know how growth is for you. I’ve been using the replacement bulbs I mentioned above and some other led strips on seedlings this year and I think things look just as good if not a bit better than under the fluorescents, but I’m not 100% sure. I’ve just started the tomato seedlings, so I’ll be watching them closely to see if they get leggy or stay nice and compact. It is just very hard to know with the lower cost LED lights since they’ve often got dips in their spectrums at different light colors so it isn’t necessarily lumens to lumens comparisons since the plants are only using parts of the spectrum.

[TheDerek]

For those interested in spectrum discussion about LED. Ive had good luck with 3500k and 3000k 90cri, Highest Id recommend going is 4000k 80cri probably but 90cri has more photons in the red spectrum which I like, but sometimes are harder to get, especially if you arent building your own fixtures. Essentially what they have found is its more about photons than spectrum. Spectrum effects morphology but growth is driven by photons. Quantities of photons are higher for the energy used when produced in the red spectrum, plants NEED some blue, but most only need 5% or so blue to grow normally. Yellow and green photons are used, but red photons are like the meat and potatoes of lights, they drive more growth for the energy used than any other color. Lumens arent a great measure for effectiveness when it comes to driving plant growth, they are weighted for human vision which is a different animal. Often a light with less lumens, but warmer light (IE more red) will produce more photons and be more effective. Lumens can be effective when trying to determine efficiency of lights of similar spectrums tho. If you have a LED light that is 3000k and produces 180 lumens/watt, it will normally be better than a light thats 3000k and produces 150 lumens/watt… Assuming they are the same CRI rating!

[forestandfarm]

Yes, for applications where plants are under lights for a significant portion of their lives, spectrum matters. For my application, starting seedling trees from nuts/seeds in the winter under lights, it is lumens and how close the bulbs can be to the seedlings that count.

[InfiniteFruit]

I made some update/upgrade to the strawberry project above. replace the relatively inefficient LED grow light panel with quantum board QB-132 v1. Running them with very low voltage. Only running at 22w (rated 75w), it did not get hot at all. We will see how these panels do.

[TheDerek]

hard to go wrong w qb i think…

[moose71]

i have peppers, black goji and 5 cultivars of alpine strawberries under mine. how long did your strawberries take to get full size? mine sprouted within a week but are still only 1/4 to 1/2in after nearly a month. they look healthy other wise. been giving the some fish/ seaweed emulsion at half strength. in comparison my peppers are 2-3in. planted at the same time. even goji is bigger.