The use of grow lights as a substitute for sunlight to improve plant growth and yields goes back many years. But quite recently LED technology spilled over into this field causing no end of a stir. So let’s examine what all the fuss is about and sift reality from opinion.

One thing that LED lighting technology can lay undisputed claim to is being the most effective means ever devised for converting electricity into light. Unlike high intensity discharge (or HID) lamps which create considerably more heat than light per watt of electricity, LED lights waste very little and thus also run cool to the touch.

The second key difference between LED and HID lamps is that the former can be made to target very specific parts of the spectrum whereas the latter emit light broadly across most of the visible spectrum. Since plants absorb most of the light they need for photosynthesis from just two narrow zones in the spectrum, HIDs not only waste energy creating heat, they also waste it creating useless (to plants) light.

It’s these twin features of very low energy consumption and precise spectral wavelengths that needless to say gained LED grow lights much attention. The ability to provide just the type of light that plants require plus low running costs and no need for expensive climate control systems is obviously an attractive proposition.

Growers were also quick to realize that since LED grow lights run cool it is possible to position them much closer to the plants without causing harm to foliage. This is turn also exploits the way the inverse square law applies to light, in that every time the distance is reduced by half, the amount of light delivered increases fourfold.

Among other advantages is the ability to seamlessly vary the blue:red light ratio to suit different phases during plant growth. HID lights rely instead on physically switching between sets of metal halide and high pressure sodium lamps. Then there are the much reduced maintenance requirements, since LEDs can remain in constant use for a decade, while HIDs demand regular bulb replacements.

So why is there even a debate about LED grow lights? The technology delivers on its claims and modern, well made LED grow lights are a match for any comparable HID unit in terms of performance and outclass them in all other aspects. The problem seems to be that there is a lot on the market that is neither modern nor well made.

It’s not uncommon to see grow light panels containing 225 LEDs being touted as using only 14 watts of electricity. Do the math – that works out at 0.06 of a watt per LED. It’s completely hopeless. To be at all effective each LED needs to be above 1 watt and even then you’ll need a unit containing about 100 of them to match a 500 watt HID. But it only takes a few bad apples for the bad press to take hold and presto, there’s your controversy.

If you found this interesting then be sure to check out these additional articles to find out much more information about LED grow lights and LED grow lights vs HID.

Tags: gardening, grow lights, growing plants, HID grow lights, led grow lights, LED lights, plants, propagation

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This entry was posted on Thursday, July 15th, 2010 at 10:33 am and is filed under gardening, indoor gardening. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.