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Oggy
Stranger Danger


Registered: 12/05/14
Posts: 1,276
Loc: Planet Remulak
Last seen: 6 months, 29 days
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*Almost* Everything you ever wanted to know about lighting! 1
#22218766 - 09/10/15 09:01 PM (8 years, 4 months ago) |
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I've seen this question posted a lot, "what is the best light to use for my indoor plants?". I've even had that same question myself. Which led to me amassing a lot of(possibly wrong) information on the subject.
I have researched a lot over this topic and have come up with my own theories. This is going to be somewhat lengthy, but hopefully it will answer any questions that anyone may have. But keep in mind, I am not an expert in any relating physics fields. I simply had these questions myself and researched many topics and subjects to put together my hypothesis and experiments. I will be paraphrasing on my own theories. This would be an incredibly huge post if I referenced everything and went into more detail over the things I have read.
Let me begin by saying a typical plant sucks at absorbing light. They are not very efficient at it. Even from our very own sun a plant has a photosynthetic efficiency of around 0.1-10%, largely depending on the species. This is due to a number of things. Wavelengths that they can't absorb, conversion losses, not absorbing photons completely, etc. It's a very long list. This is all pretty sad given the fact that they're better at it than we are.
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Wattage and Lumen: Watts and lumens(to an extent) play no direct role in plant growth. Lumen is a unit for measuring the brightness and total amount of visible light that you see. Wattage is a measurement of electricity usage in an electronic such as a light.
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Color Temperature: [edit]*gone to the library* I stand by what I said about it being a horrible way to measuring temperature through color, though.
left in for record: Color temperature is a horrible way of measuring how a color can look warm or cold to our eyes even if it's an inanimate object, picture/painting or anything else we can observe with our eyes. For example when you look at a picture of a sunset. It has no observable temperature it just looks warm. Another example would be if you observe a sunset in the dead of winter buried under 30 feet of snow, the sky would still look warm and inviting even though you're freezing to death. Again, this is not important to a plant. They don't have eyes. What effects them is the wavelength these lights produce.
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Wavelength: This is the most important aspect of growing a plant under artificial light. Wavelength(also the color you see) is absorbed by Chlorophyll A and B, as well as many carotenoids. Chlorophyll A and B are usually green pigments. Carotenoids normally aren't. You only notice them around fall however they are always present. There job is to assist in light absorption when chlorophyll 'a' and 'b' aren't as abundant later in the season.
Wavelength efficiency is a strange concept to me. But the way I understand it, the plant has more dominant pigments of chloroplast, some pigments are more abundant than others which results in certain wavelengths being absorbed more. This, unfortunately, also means that wavelength peaks will always be unique to the plant. When we talk about lighting efficiency we really mean any light that is not green would be cost efficient. If you see green, you're wasting money.
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Now the part that you probably want: which wavelengths are more efficient than others? Because it will depend uniquely on the plant, I can only give you 6 numbers for average efficiency. The wavelengths that would mimic spring and summer are around 430nm for chlorophyll a, 453nm for chlorophyll b and 448nm for carotenoids. The wavelengths for mimicking fall are 662nm for chlorophyll a, 642nm for chlorophyll b and 612nm for carotenoids.
Of course, the more wavelengths that you can target that are not in the green spectrum the better. But this is not likely to happen for indoor gardening because you would need hundreds of individual lights that could output specific wavelengths. White light contains every wavelength. Since a plant can't use a very large portion of that light then it's not efficient. But a white light from most bulbs you buy will let you target all peak wavelengths that would be unique to the plant. The plant wouldn't absorb the light as efficiently as it would if it had no green though.
Now, LEDs are a completely different beast. LEDs emit only one wavelength. They will never emit two different wavelengths at once. But, this also comes at an unfortunate price. You will never have an LED that emits the exact wavelength you want due to a number of reasons. Circuit resistance, electromagnetic interference, heat, age, etc. This does have a fortunate side though. You will inadvertently output wavelengths of different, but very close ranges to whatever the spec sheet of the LED says. If the LED says it outputs 430nm, it will most likely output anything between the ranges of 420nm and 440nm. To get as close to 430nm as possible you would need to use a lot of the same LEDs. Say around 20 LEDs of each wavelength would a safe estimate. There would be a chance none of them would be outputting 430nm though. But thankfully the plant can still use them for energy regardless. So you're looking at around 60 LEDs per array(20 for chlorophyll a, 20 for b and 20 for carotenoids) for each season.
And I'm done.
I will revise this later, with references and sources. I also want to hear any clarifications and corrections. We can use this page for a group discussion. And if anyone has any questions please feel free to ask them. I will enjoy researching any interesting questions to pass along theories and hypothesize over.
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Edited by Oggy (09/13/15 07:53 PM)
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cowsRmeat
Don't step on the MomeRaths



Registered: 04/23/14
Posts: 3,153
Loc: Wonderland
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Re: The long overdue "how do I choose the lights to use indoors?!" thread. [Re: Oggy]
#22223999 - 09/11/15 08:10 PM (8 years, 4 months ago) |
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Thanks for the read
-------------------- One day Alice came to a fork in the road and saw a Cheshire cat in a tree. 'Which road do I take?' she asked. 'Where do you want to go?' was his response. 'I don't know', Alice answered. 'Then', said the cat, 'it doesn't matter.'
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Oggy
Stranger Danger


Registered: 12/05/14
Posts: 1,276
Loc: Planet Remulak
Last seen: 6 months, 29 days
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Re: The long overdue "how do I choose the lights to use indoors?!" thread. [Re: cowsRmeat]
#22229044 - 09/12/15 09:09 PM (8 years, 4 months ago) |
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No problem! Happy someone out there read it!
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spaceman101
Friend to all



Registered: 01/18/13
Posts: 11,726
Loc: In heaven bored as hell
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Re: The long overdue "how do I choose the lights to use indoors?!" thread. [Re: Oggy]
#22229211 - 09/12/15 09:54 PM (8 years, 4 months ago) |
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I'm in the process of checking it out too just posting here until I can find some spare time to get through it
BTW I read REALLY FUCKING SLOWLY
-------------------- ------------- Check out my Pollen Trade thread for spreading Good genetics far and wide Great Vendors thread where we can discuss "Non Shroomery" Vendors that sell good products worth checking into A few things I wanna get my hands on check it out and let me know if you have any of these Need help getting started growing mushrooms Here's The Noob Forum
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invitro

Registered: 05/03/13
Posts: 2,529
Last seen: 1 month, 21 days
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Re: The long overdue "how do I choose the lights to use indoors?!" thread. [Re: spaceman101]
#22229601 - 09/13/15 12:10 AM (8 years, 4 months ago) |
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You've completely misunderstood what the term color temperature means, 'temperature' is actually involved in describing color temperature. That bit of science is not something you really need to delve into though.
Color temperature IS however a useful tool to the layman, as it can be used as a broad indicator of color wavelengths in the light, more blues vs. more reds, which is a important distinction to make in many situations regarding horticulture.
A search on wiki would have told you that, you could have done some better fact checking before posting.
Edited by invitro (09/13/15 12:15 AM)
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Oggy
Stranger Danger


Registered: 12/05/14
Posts: 1,276
Loc: Planet Remulak
Last seen: 6 months, 29 days
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Re: The long overdue "how do I choose the lights to use indoors?!" thread. [Re: invitro]
#22233680 - 09/13/15 07:37 PM (8 years, 4 months ago) |
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invitro said: You've completely misunderstood what the term color temperature means, 'temperature' is actually involved in describing color temperature. That bit of science is not something you really need to delve into though.
Color temperature IS however a useful tool to the layman, as it can be used as a broad indicator of color wavelengths in the light, more blues vs. more reds, which is a important distinction to make in many situations regarding horticulture.
A search on wiki would have told you that, you could have done some better fact checking before posting.
Sorry, but I'm a bit confused, you just described color temperature exactly as I did in my original post. You can also look at the wikipedia entry which quotes, "Color temperature is a characteristic of visible light".
[edit] Perhaps I used the wrong words to paraphrase as I did. I should probably not have put so much emphasis on how color temperature matches the intuitive understanding objects and temperatures.
I'll edit that for a while and hit the books on this one to double check I have the definition.
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Edited by Oggy (09/13/15 07:48 PM)
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