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Anyone familiar with grow lights???  RSS feed

 
Matthew Steffen
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In my potting shed where i grow all my starts i have been using 6 bulb T5 florescent fixures in 4100K rating and i am thinking about switching to LED's. Anyone know what K rating i should go with in an LED or better yet a spacific bulb to use? I realize i will have to take the ballasts out which is no big deal. Any help would be appreciated.....
 
Andrew Jackman
Posts: 28
Location: Salt Lake City, UT
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I'm not an expert, but I use Mars Hydro lights from eBay. They're cheap, durable, and effective. There might be better lights, but my plants are doing great.
 
John Weiland
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Location: RRV of da Nort
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Matthew,

Sometimes some of the LED tubes out there do not require you to by-pass the ballast, so something to keep in mind. As for the color temperature, I would go with whatever stimulates vegetative growth, but that's just a guess:

"Colors above 5000K are known as cool colors (blue) and closely resemble natural sunlight. Colors below 3,000K are known an warm colors (red). The spectrum of light is important to horticulture because each spectrum triggers different responses from the plants—**blue light induces vegetative growth**, red light induces flowering. This in turn plays into which type of lighting rig you'll use and when—some types specialize in certain parts of the spectrum while others can span multiple wavelengths."

--http://gizmodo.com/5903134/better-know-a-grow-light
 
David Spohn
Posts: 20
Location: Alberta, Canada
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I've been using LED grow lights of various kinds for over 5 years now, and they are revolutionizing artificial light for plants. One reason for this is that LEDs can focus specifically on the colours of light the plants need, and not waste power on other colours.

Colour temperature (measured in Kelvin) is less relevant to the discussion in the case of grow LEDs, because it applies mostly to hues of white light, akin to the sun. But photosynthesis doesn't use the whole spectrum (at least, not equally). It uses mostly red light, and some blue, and not much if any of the other colours, although I don't doubt that there's still some debate about the perfect combination, and that may also vary from one type of plant to the next. So, most LED grow lights appear red when you turn them on, and the vast majority use both red and blue LEDs, usually at a ratio of about 4 or 5 red for each blue. A light for vegetative growth typically has a higher ratio of blue than a flowering light, but it will still be mostly red. You can buy pure red and pure blue lamps, but they're intended to be used as supplementary lighting. Some companies are now putting a small amount of infra red, ultraviolet, or white into the mix, but I don't know if there's any science to justify it or whether it's just a gimmick.

What I've found is that lights with fewer, higher-powered LEDs are better than lights with more, lower-powered LEDs. That is, one 3W LED will serve you better than three 1W LEDs. This is especially true when it comes to lights made with individual LEDs that are less than 1W each, which, although they "work," seem to have relatively poor penetration.

I've never tried an LED replacement bulb in a T5 fixture, but I'd start by comparing the price of 6 LED bulbs with that of a new fixture. I've had pretty good luck ordering the stuff from China through eBay, as it all seems to come from there anyway, and there's very little available locally.
 
Matthew Steffen
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David Spohn wrote:I've been using LED grow lights of various kinds for over 5 years now, and they are revolutionizing artificial light for plants. One reason for this is that LEDs can focus specifically on the colours of light the plants need, and not waste power on other colours.

Colour temperature (measured in Kelvin) is less relevant to the discussion in the case of grow LEDs, because it applies mostly to hues of white light, akin to the sun. But photosynthesis doesn't use the whole spectrum (at least, not equally). It uses mostly red light, and some blue, and not much if any of the other colours, although I don't doubt that there's still some debate about the perfect combination, and that may also vary from one type of plant to the next. So, most LED grow lights appear red when you turn them on, and the vast majority use both red and blue LEDs, usually at a ratio of about 4 or 5 red for each blue. A light for vegetative growth typically has a higher ratio of blue than a flowering light, but it will still be mostly red. You can buy pure red and pure blue lamps, but they're intended to be used as supplementary lighting. Some companies are now putting a small amount of infra red, ultraviolet, or white into the mix, but I don't know if there's any science to justify it or whether it's just a gimmick.

What I've found is that lights with fewer, higher-powered LEDs are better than lights with more, lower-powered LEDs. That is, one 3W LED will serve you better than three 1W LEDs. This is especially true when it comes to lights made with individual LEDs that are less than 1W each, which, although they "work," seem to have relatively poor penetration.

I've never tried an LED replacement bulb in a T5 fixture, but I'd start by comparing the price of 6 LED bulbs with that of a new fixture. I've had pretty good luck ordering the stuff from China through eBay, as it all seems to come from there anyway, and there's very little available locally.



David, What ratio do you suggest for seed starting?
 
David Spohn
Posts: 20
Location: Alberta, Canada
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David, What ratio do you suggest for seed starting?


I'm sort of experimenting with some small lamps I found that are 2 red for each blue, but that's probably more blue than you need. I'd guess a 3 to 1 or even 4 to 1 ratio would work just as well, if not better. So a lamp designed for vegetative growth should do the trick. The tech is changing pretty fast, and some lamps now even have switches for vegetative and flowering modes.
 
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