by Angela Lundmark

Determining the Mounting Height for LEDs

Through experience we have developed general guidelines to follow when hanging LEDs. For instance, a single LGM5 should be mounted 28-18" from the top or sides of your plants. One of the few common characteristics of traditional lighting and LED lighting is that they both follow the Inverse Square law for light intensity. The light intensity decreases as the square of the distance from the light. For example, an LGM5 hung at 36" will have approximately 1/4 of the intensity of the LGM5 at 18". This is a large range of light intensity that enables growers to adjust for the needs of different plants.

Because 100% of the light emitted is being used by your plants (as opposed to 10% of the light from traditional lighting) there is a danger of giving your plants too much light. Hanging the bar further away will increase your coverage area but decrease the intensity. Hanging the bar closer will decrease your coverage area but increase your light intensity. The exact mounting height that will satisfy your plant's light requirements can only be judged by observing your plants reaction to the light, and of course, good old fashioned common sense.

Changes in light intensity should be gradual. A plant that naturally grows in the deep shade of the rainforest will likely suffer if an LGM5 is placed at 20 inches over the plant. A plant that naturally grows in the bright sunlight may thrive at 20 inches. Like all light sources, the bars will need to be raised to maintain this distance from the plant.

Remember that plants will generally survive a period of low light but too much light may permanently damage them. This is why we recommend that you start your bars off close to the maximum distance recommended and then watch for signs to determine if the bars should be lowered. If you have a nearby window and you see your plants leaning toward the window you may want to lower the bar. If there is not another light source and the plants are leaning away from the LEDs it could be a sign that they are getting too much light. Not enough light will cause leaves to turn yellow but too much light will bleach the leaves. If the bar needs to be closer you may see reduced leaf size and longer internodal lengths. If upward growth stops- the lights should likely be raised.

Once you have determined a distance that is promoting the vigorous growth you are looking for you can assume that this is the optimal mounting height. Different plants have diverse needs and there are many environmental factors that can also cause the symptoms listed above.

Angela Lundmark, CEO of LED Grow Master Global. She may be contacted by calling 866.414.7244 or visiting www.led-grow-master.com.