Ask Erik

Fredo,

I always do my best to help keep the readership informed and up-to-date on the many new technologies that are emerging for indoor growers. It takes a while to draw accurate conclusions about new technologies, and often while we are trialing the latest and greatest, the technologies being tested are advancing. So, sometimes our data becomes obsolete due to improvements or changes in the technologies being tested.

I expect to see lots of advances in LED (light emitting diode) lighting for horticultural crops in the next while. This may lead to some major changes in the way people grow indoors, and the number of people that grow indoors; possibly paving the way to a horticultural renaissance of sorts.

My conclusions regarding LEDs are only as up-to-date as the time of this writing. By the time you read this in print, there will likely be more advances in the way of LEDs.

At present, high output LEDs, which typically range from 0.3 watts up to 3.0 watts (per diode) are capable of producing very healthy plant growth. The higher the wattage of the diode, the more light they can emit; resulting in better cropping potential.

Firstly, power consumption for lighting is drastically reduced, typically by up to six to 10 times! Now factor in that the diodes and fixtures emit negligible amounts of heat, and you further reduce your electrical consumption that is associated with keeping temperatures in the optimal range with exhaust systems or air-conditioning. The initial cost of an LED fixture is quickly offset with the savings in electricity, and the fact that cooling equipment purchases and power consumption are greatly reduced or eliminated.

So far it has been found that using one of the higher end high-output LED plant lighting systems comprised of one watt or greater per diode for a total of near 100 watts total can help to give results comparable to a 250 watt or even 400 watt HPS lamp. While the electrical savings is very significant, the fact that the lighting does not heat up the growing area allows for very efficient use of supplemental carbon dioxide; offering the potential to increase yields.

Because they are so cool running and the fixture requires very little space, you can set-up an LED lit garden in just about any space that is tall enough for your desired crop. Best of all, your garden can run near silent, as minimal air movement and exchanges will be required. Lots of growers find that using LEDs help to reduce their watering requirements also.

However, while it has been noted that LEDs emit only light wavelengths that the plants need, making them very efficient, it seems that there is the need for further development on just what it is the plants need in terms of light wavelengths exactly, and how this changes through the various growth phases. Many growers report that they can significantly increase their growth rates and yields by coupling a small amount of fluorescent lighting with their cool running LED systems. The extra “warm” and visible light wavelengths emitted by the fluorescents seem to give flowering plants that little something extra to produce better versus just blue and red LEDs alone.

LED manufacturers are refining their diode color ratios to help create the ideal spectrum for plant growth. Interestingly, the pioneers of LED light growing are learning that different plants seem to have different needs in this regard, and further to that, these needs change through the various growth phases.

So for the space allotted here, I will say that a high quality and high output fixture, coupled with a minimal amount of supplemental fluorescent lighting can produce some nice results that should satisfy the hobbyist looking to produce a small crop for their own well being. Larger scale HID gardeners should watch this technology closely, as it seems more and more likely that LEDs may have the potential to replace their HIDs in the not too distant future.

Greenhouse growers, wishing to supplement lighting levels or increase day lengths may find high-output LEDs especially attractive.

Look for more research and information from myself and in the many pages of this magazine for further developments in this exciting growth technology.

Cheers, Erik Biksa