What are Enhanced Spectrum Grow Lights?








Q: What are Enhanced Spectrum Lights?

A: The High Intensity Discharge Light manufacturers have been responding to the needs of plant growers by coming out with new bulbs that shine the colors that plants use the most.

Early attempts used a High Pressure Sodium bulb that was modified with a little bit of blue light. These "Son Agro" bulbs were manufatured by Phillips. They worked especially well in greenhouses or supplementing Natural Light on Blooming plants. Now, in the 21st century, some Metal Halide Lights have been modified to provide a more complete light for plants. The best of these so far has been the "Clean-Ace" bulb developed in Japan especially for plants. The "Clean-Ace" Metal Halide bulb comes in 250 Watt size and 400 Watt size and will burn in any standard Metal Halide fixture of the same size. It costs more than a standard or Super Metal Halide Bulb, but can be a good compromise for those on a budget.

A large benefit of the Clean Ace bulb is that its color spectrum helps indoor plants stay compact with tight spaces between branches and leaves. This can be especially important if you are trying to grow tomato plants in a bush shape rather than as a vine. Often the varieties of plants which have a natural tendency to grow into a bush shape are called "determinate"; seeds which have a natural tendency to grow as vines are called "indeterminate". The added blue light of the Clean Ace helps keep the bushes compact, especially when grown near a window.


Q: What else have you got?

A: Sunlight Supply has come out with a "Switchable Ballast". It comes in two sizes 400 WATT and 1000 WATT. This jasper is the latest in technology and allows the ballast to run either a Metal Halide Lamp or a High Pressure Sodium Lamp by flipping a selector switch. One note here: if you buy this light system, you will need two separate bulbs. Make sure you check the fine print on other websites or stores to see if two bulbs will cost extra or if shipping will be an add-on as well as the price of the system itself. Look at your total cost, 3R Lighting gives you excellent value.

Q: What is this Kelvin temperature? What does it have to do with color?

A: The Kelvin temperature scale was created by an Englishman, Lord Kelvin. He was royalty, so he named it after himself. The Kelvin temperature scale is just the centigrade or (Celsius) scale, but the bottom point or zero is placed in a different place. On the Kelvin scale, there can be no numbers below zero. On the centigrade scale, zero is set at the point where water freezes--what we know as 32 degrees. The Kelvin scale starts out at 273.18 degrees below zero measured on the centigrade scale. This is a pretty cold 524 degrees below zero in standard measurements.

Q: So, what does this have to do with the color of lights?

Lights shine with different colors, the plants can use these different colors to do different things. The Kelvin temperature is just one way to compare the colors between different lights.

Back in the 19th Century, on Broadway, in New York City, some theaters had the idea that if you took natural gas and heated limestone very hot, it would start to glow. They placed these limestone heaters spaced around the foot of the stage with reflectors to keep the light from blinding the audience. The limestone glowed green--but a very bright green. This let them hold plays at night instead of only in the afternoon. Needless to say, the theater owners and producers made a whole lot more money with evening shows than with just matinees.

Q: Were they nuts? That sounds dangerous as all get out!

A: Yes it was. Theater curtains and ladies hoop skirts could really go up in flames, but the actors all enjoyed "being in the limelight."

Q: What does this have to do with 21st Century growlights?
A: Some people figured out that if you heat some black material it will glow with light. As you heat it, the color changes. The temperature where the color changed was measured. So red was in the 1500 to 2000 degree range, morning sun was in about the 4,000 degree range, light blue at about 4,500 to 5,000, dark blue 5,500 to 6,500, and an average blue sky with natural sunlight compares to about 16,000 degrees Kelvin.

Get this part straight, though--all light bulbs or tubes shine with a range of colors--not just one color. The Kelvin temperature rating is based on the color where the highest output comes out. Kelvin rating says nothing about how wide the color range is or how powerful the light is, it is only a guide for comparison.

For example, moonlight is often rated at 4,000 degrees Kelvin, but I wouldn't try to grow plants with only moonlight.



























© 2002-2004 K.Kelly and 3R Lighting