Top left: quantum boards.
Top right: DIY CREE COBs.
Bottom right: eBay 70w led cob panels.
All around 3000k to 4000k colour temperature range.
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I would only recommend white light LED lights in this day and age. My thoughts on colour temperature:
Warm white (3000k) to daylight (6500k) is fine.
3500 to 5000k is great.
4000k is best for leafy greens, in my opinion.
3500k is best all-around compromise (in my humble option) for fruit, flowers, leafy greens and eye pleasing aesthetics.
3000k in the lowest CRI is probably the most efficient.
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A great pre-made growlight is in the $150 ballpark. "You get what you pay for" and "buy it right or buy it twice" is like death and taxes, you just can't avoid them. That doesn't mean there are not options:
High end (there is a range of products here at different price points, check the cheap one also)
Mid level (quantum boards, not polished, but very good)
Entry led shop light
Entry led shop light
Entry led shop light
Basement (add supermarket led globes)
You could defiantly find better prices with some searching. Links are for example only. "Quantum boards" (with LM301B chips) is the rich & educated persons choice.
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So I don't like burple (blue/red) LED lights for reasons (This includes discreet colour emitter arrays. I'm however intrigued by the current trend of white + red and the specialised horticultural burple COBs that are starting to reach the market).
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Primary there is a reason that burple arrays are so cheap, they are bordering on obsolete. One good red or blue discrete LED emitter are around $1 each. So if a burple array has 100 LED's and costs less than $100, there is no way it is using good discrete LED emitters. If it is too good to be true...
So my point here is that no-one asking here is buying anything like current premium horticultural burple lights, and most of those manufactures are talking white lightLEDs now anyway. We are at high risk of being sold cheap last generations (or worse!) surplus discreet colour emitter arrays from predatory marketers taking advantage of us.
There is no real efficiency advantage remaining, for example with Samsung horticulture LED offerings:
red (2.32 μmol/s, 3.12 μmol/J @ 350 mA)
blue (2.80 μmol/s, 2.80 μmol/J @ 350 mA),
white (0.54 μmol/s, 3.03 μmol/J @ 65 mA, 6500K)
white (PPF: 2.32 μmol/s, 2.32 μmol/J @ 350 mA)
The white mid power emitter is more efficient than the blue power emitter and near as efficient as the red emitter (0.09 μmol/Joule advantage for Samsung red over white. or 0.09 μmol/Watt) Just get a more efficient power supply on white array and your already ahead.
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Plants actually use green light quite well. McCree curve, again and again. Most biology text books and wikipedia uses misleading charts (This is not me speaking. I'm standing on the shoulders of giants). This is what I was struggling with a few years ago, I even spent time chasing the magic spectrum.
To quote u/SuperAngryGuy : white LEDs are basically 100% PAR including the blue light (radiation) that excites the phosphor. If you find a chart with a <em>deep dip in the green area</em> then it's for some sort of algae or bacteria, not green terrestrial plants. If you find a chart with a bunch of <em>chlorophyll and other pigment peaks</em> then it's only valid as an extract in vitro (in the test tube or cuvette) and not in vivo (the living leaf itself). The pigment peaks can differ depending on the solvent used and the charts do not tell how much there is of a particular pigment so take them with a grain of salt. They are only valid for the particular set up used. .
Link oh and read SAG lighting guide over at r/HandsOnComplexity.
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The benefit of white over burple
To quote u/timeactor :The best thing: We (My girlfriend and I) always stop on that greenhouse on our way to the fridge or to the bath, and have a looooong look at all the growing stuff. to stare at all the plants, and it takes a 5 minute chunk of your live every time you walk by, staring at the plants. It is so fun, I love it so far. Added bonus: The automatic light timers are set to, that I don't need other lights in my kitchen anymore.
To quote u/haharrison : I take my lightning knowledge from the cannabis group because they take their lights very seriously as it has a much bigger impact on them than it does for us simple houseplant folk.
Would buying a more expensive one benefit my plants more?
More light = more plants under light. More light is better up until a point for better plant growth, less elongation ect.
Look at some good websites for grow lights, they will mention something along the lines of "this massively powerful and expensive light is only good for 2-3 foot square area" or they will lie. See r/SpaceBuckets r/microgrowery for more about cramming high intensity lighting in a small space.
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Since I am name dropping it would be remiss to end without a paraphrased comment from u/canadian1969 : predatory marketers have be taking advantage of [a knowledge vacuum in regard to LED growlights] despite advances in the technology and market growth.
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PS: I'm not trying to sell you anything, indoor gardening under LED's is my hobby. My best advice is just do some of your own research, hydroponics, photosynthesis and LED's are fun topics.
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Edits: My apologies. I intend to update this post and refer people to it. I'm starting to repeat myself, out there, answering the same lighting questions, and I find that boorish.