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T5 Vs T8 – The Best Grow Light for Indoor Gardening

Two fluorescent lights grow on the market

When looking for indoor fluorescent lights, you may have heard that T8 fluorescent lamps are more efficient than the T12 standard. You may also have heard a buzz about other new fluorescent lights, the T5 High Output (HO). So what are the pros and cons of these two different technologies? How do they compare and which is the best for your garden?

The difference

The fundamental difference between these two fluorescent bulbs is reflected in their names. T8 bulbs have a diameter of eight eighths of an inch (equivalent to 1 inch thick). T5 bulbs are thinner at 5/8 of 1 inch thick.

Many indoor gardeners prefer T8 grow lamps over T12 because they produce more overall lumens than regular T12 fluorescent lamps, have a longer lifespan and are more efficient.

The advantage of high power T5 bulbs is that they are still around 9% more efficient than T8, they can produce more light in a smaller amount of space and use less power (75 to 90 lumens per watt). T5 HO also has high color rendering properties (CRI), which means that they are visually more appealing. (The color rendering index is only important when you worry about how light looks to the human eye, but not necessarily important for plants.)

However, despite higher efficiency, T5 bulbs require more expensive different devices. Another downside is that they tend to have a life of about 10,000 hours less than the average 20,000 hours of T12 and 30,000 hours of T8 tubes.

If you look well enough, you can find T5 bulbs with a longer lifespan, so be sure to check this specification before purchasing.


Both T5 and T8 bulbs can actually be used as the main lighting , as well as additional lighting for your indoor garden.

T5 bulbs emit more lumens and send more heat than other fluorescent lamps, so you may need to use a small fan to keep plants cool when they are under these bulbs.

So with all this comparative information, the clear winner would be …

Hold down the Print button!

Before you go out and buy your new more efficient T5 grow light, there is another, even newer, option that you will want to consider!

The latter fluorescent light technology is called “Super T8”, and is actually a high-performance T8 bulb that competes with the efficiency of T5 HO bulbs and has some more advantages, such as longer lifespan.

Before going out and buying any other high-performance light bulbs, you will definitely want to learn more about the Super T8 bulb to see if it could be the right indoor grow light for you.

by Becky Sheldon

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