LED Grow Light Guide (Part One)


LED Grow Lights

Whether you grow eggplant or herbs, if you want year round harvests then you will have to bring your plants inside. But once inside, you’ve lost a powerful growth variable: natural sunlight.

You probably already know that LED grow lights emit less heat, have lower energy usage and last a very long time when compared to other lighting systems.

Another advantage is the element of control. Basically, you want an LED grow light that best imitates natural light while still allowing you control over light quality.

What to look for when buying LED lights?

LED Grow Lights

Watts and Lumens and PAR

There are gardeners out there who strongly believe that LED manufacturers lie. This isn’t  true. Some of the specs may seem misleading, but if you understand how LEDs work then you will understand what you are getting.

Each bulb pulls energy to create light. The amount of energy pulled is measured in wattages  or W. Wattage doesn’t have all that much to do with light intensity. And this is where people get confused.

Watts measure the amount of energy used to power the bulb. Watts do not measure light intensity. Light intensity, or luminosity, is measured in lumens.

Watts and light intensity are not equivalent. Replacing an incandescent bulb with an LED panel of the same wattage will not give your garden similar outcomes.

If you are looking for an LED panel that doesn’t use much energy then look at lower wattages. If you are looking for an LED panel that has high intensity light, then look at lumens. Most growers look for panels with low wattage (low energy consumption) and high lumens (light intensity), but this strategy is a bit flawed.

The problem here is that lumens are measured by the amount of light visible to the human eye. This doesn’t have much to do with what plants need for growth. Plants utilize different portions of the light spectrum. Because of this, you will want to look for high rates of photosynthetically available radiation (PAR).

Where do you look? Most LED manufacturers list the amount of watts, and that’s great to determine the amount of energy you will use. To determine light intensity available to plants (PAR) you will have to look at wavelengths, also called bands. The more bands, the more intensity. But more doesn’t always mean better.


Full spectrum white light is the closest you can get to natural light. Most LED light panels feature 3 to 8 bands of visible light. These panels are not full spectrum but they still have positive results. They are also cheaper than full spectrum LED panels.

If you really want full spectrum light without paying for a full spectrum LED panel, there are web sources that explain how to mix a variety of LED bands to create full spectrum white light. That’s a bit too intense to cover here, and may be a bit too intense for anyone. But, many growers agree that the most important bands are red and  blue, if you have these two covered then you should have happy plants.

You’ll notice that many LED panels mix shades of blue and red. Plants grown in these conditions will be even happier. Some commonly found LED panels mix blues and reds to create orange and purple lights.  Orange light helps plants flower. Purple light emits low heat and penetrates beneath canopies.

Some LED systems also include ultra-violet and infra-red light. These invisible rays aid in cell division, plant growth and decrease the amount of bacteria on leaves. All three are important for indoor growers.

Coverage AreaLeD-Grow-Lights

LEDs have a bad reputation when it comes to coverage area. Some growers claim the lights don’t cover a wide enough area for large grows and don’t uniformly penetrate tall plant’s lower leaves. However, manufacturers have designed around the issue.

LED systems with dual focusing lights allow the grower to adjust the angles of light so that more areas of the plant receive uniform light. This is especially helpful during the vegetative stage.

Reflectors and reflective fixture housings also increase coverage area. Some growers recommend purchasing two or more 125W panels and placing them together to increase light. However, growers using single 240W and 450W panels also report good results.

Overall, most growers suggest that LED panels work best for small plants and small growing areas. LED light systems are also praised for growing high quality plants.

Go to LED Grow Light Guide (Part Two)


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