Many first time grow light users or those who want to start to dabble into growing their plants under artificial lighting at first are very confused about all the different color temperatures or color spectrums of T5 grow light bulbs, so here is a little guide to help you understand them and to use your lights better and to their full potential.

First off I should explain a bit more about the terms that will be used in this article and that need to be known for you to fully understand grow lights. I previously mentioned a color temperature, and what that means is that the color temperature is the measurement that shows  in what hue your grow light will be, and it is measured in Degrees Kelvin or Kelvins for short. Color spectrum or the visible spectrum is the light that we can see with our eyes, we can differ various colors or hues of the light, but when it comes to be precise then better to stick with the color temperature measurement to ensure that your plants get the light they need in the specific stage of their growth.


6,500 Kelvin bulbs

The most common bulbs sold are ones with the color temperature of 6,500 Kelvins, because usually these types of bulbs come with T5 fixtures and have the biggest selection among different manufacturers. Sometimes there are 6,400 Kelvin or even 6,505 Kelvin bulbs that are essentially the same thing, because all these bulbs will emit light that is similar to the light that we see during daylight hours, it is called a daylight white light and it has blue tinge to it. In fact any bulbs that have the color temperature of 5,000 Kelvins and up will emit daylight white light, it only will slightly differ how cool or blue the light will be.

This type of light is best and most useful for plants that are growing or in their vegetative stages of their growth, because the light is similar to light that they would get if they would grow outside during daylight hours. Also this light is good for seedling and cloning of the plants because of the same daylight reason.


3,000 Kelvin bulbs

The other most common color temperature in T5 bulbs is 3,000 Kelvins. Some manufacturers make bulbs with 2,700 Kelvin or 2,900 Kelvin color temperature, and again they are produced for the same purpose as 3,000 Kelvin bulbs, and the difference in the color temperature really isn’t noticeable, because any bulbs from 2,700 to 3,000 Kelvins are in warm white or bright white color and have more red and orange hues to the light.

And thanks to the fact that these lights have more warmer tones to the emitted light, that simulates the color the daylight would be in sunset hours, which promotes  higher rates of photosynthesis which in return affects plant  flowering and budding and essentially makes the yield of your plants bigger.


4,100 Kelvin bulbs

There are also bulbs that have the color temperature of 4,100 Kelvins, that although aren’t that common, is still useful to the plants and worth looking into. The color temperature from 4,000 to about 5,000 Kelvins creates a neutral weight light, that have balanced level of blue and red/orange tones to it. To the human eye they can seem as they have light blue tinge to them though.

Because the light is neutral, not leaning in favor of red or blue spectrum, it can be described as standard and therefore can promote plant leaf as well as stem growth, but can be also used when the plants are flowering. The only thing is this light won’t have as big of an effect on the plants – their growth or yield – as would two previous color temperatures would, but it still will help the plants especially if they are grown in winter. These bulbs are good for those who don’t want to switch the bulbs or fixtures and use only one type of light and bulbs all around.


10,000 Kelvin bulbs

And you can also find T5 bulbs with the color temperature of 10,000 Kelvins. Most commonly they are used as aquarium lights. The 10,000 Kelvin color temperature means that they are very blue based lights so they can be used as grow lights for extreme plant growth, because of the cool color of them.

But they usually are used for marine aquariums that have reefs and fresh water type of marine life in them, because the color spectrum also is quite similar to the light that could be seen in deep waters or ocean. So for all those who own fresh water aquariums or simply want to experiment with plant growth these bulbs are for you.