T5 Lighting Guide: Tips on How to Use Large T5 Grow Light Fixtures Effectively

T5 grow lights are a top pick among growers in 2020, and it’s been this way for decades. This fluorescent tube lighting is efficient, budget-friendly, and easy to use, so it makes sense that many growers are still opting for T5s over the more expensive LED and HPS systems.

Before you start using T5 fixtures in your grow room, there are a few things you should know so that you can use them as effectively as possible. Sure, fluorescent lights are efficient and affordable, but any light system can go wrong if executed without doing the right research. Start here in this guide to T5 lighting.

What Is T5 Lighting?

T5 grow lights are a type of fixture that uses fluorescent bulbs. The ‘T’ represents the shape of the bulb, which is tubular, and the ‘5’ represents the size, which is ⅝-inch in diameter. Although many growers are now utilizing other types of bulbs, like LEDs, T5 lighting is still considered the industry standard for the early stages of plant development.

How Do T5s Compare to Other Fluorescent Lights?

In this article on the best T5 grow lights available, Cannabis Growing Canada says that “there are other types of fluorescent grow lights, like T8 and T12 bulbs, but T5 bulbs are the go-to since they’re the most efficient and the cheapest grow lights to run. The others have basically become obsolete because there’s really no comparison between the other guys and T5s.”

In terms of sizing, any type of fluorescent lighting, whether it’s T5, T8, or T12, can come in different lengths. The standard length options for indoor gardens are 2 feet and 4 feet, but no matter which size you go with, T5s are the most efficient while also producing the least amount of heat.

Benefits of T5 Lights for the Development of Indoor Plants

Efficiency is the #1 reason for growers to utilize T5 lighting in a grow room setup. These energy-efficient light bulbs “typically use about 25%-80% less energy than traditional incandescents, saving you money” (according to Energy.gov) and they have a lifespan that’s 3 to 25 times longer than incandescents.

On top of that, T5 lighting is affordable. Unlike LEDs, which are also insanely efficient, a large T5 light fixture won’t break the bank. Similar to LESs, T5 grow lights don’t give off too much heat, which is an added benefit for grow rooms with low ceilings and fewer ventilation options.

Flaws of T5 Lighting

No type of grow room lighting is perfect, and with all the pros come a few cons. The first drawback of T5 grow lights is that the light they produce isn’t far-reaching. This means that you have to hang the lights very close to the plants in order for it to penetrate the canopy. The good news is that the low heat output of T5 allows you to do this without burning the plants.

The light from T5s isn’t known to emit outwards (only downwards) so you’ll definitely want a fixture that’s built with quality reflectors. That’s not a huge deal, though, since it’s a good idea to have quality reflectors no matter the lighting you choose.

When to Use T5 Grow Lights

One thing that is important to realize about fluorescent lighting like T5s is that they’re not generally used for an entire grow op. Although a complete beginner or a grower with 2 plants in a closet grow room might use T5s all the way through, a commercial or more advanced grow system would probably use a mixture of T5s and another higher-output system, like HPS lights.

Although it is definitely possible to use T5 lighting through flower and get pretty decent yields, the better option is to make the switch from T5 lighting to something strong once the plants reach a maximum of 24 inches in height. That way, the crop will get an extra boost during the flowering stage, which will likely result in denser, bigger buds.

Helpful Tips for Using Large T5 Grow Light Fixtures

No matter the type of lighting you go with, the most helpful tip to remember is that it’s all about the layout. Before you start growing, draw a layout of the grow room based on square footage and the number of plants you plan on growing within the room or tent. Then you can choose the right T5 lights based on their wattage.

Hanging Distance

In terms of hanging distance from the plant canopy, try to hang your T5s as close as possible to the plants without burning them. While other lights have to be hung farther away as to not singe the plants, fluorescent lighting is only useful within about a foot. If any part of a plant is further than 12 inches from the light, chances are it will suffer.

Consider Using HO T5s

High output T5 lighting is more effective for delivering photosynthetically active radiation to a plant (PAR). We won’t get into all the science of it, but PAR is specific wavelengths of light that are best utilized by plants for photosynthesis. High output T5s are better at delivering these wavelengths than standard T5s, so look for the letters “H-O” on a fixture before buying it.

Don’t Assume that Heat Isn’t An Issue

One of the biggest benefits of T5 lighting is the low heat output, but that doesn’t mean you can assume they give off no heat whatsoever. All lights give off heat, and even though T5 lighting runs cooler than other types of lights, every grower still needs to be concerned with light temperature.

You could argue that monitoring heat is even more important with T5 lighting since these fixtures need to hang close to the canopy. Even though plants don’t usually die-off from heat, they can still be negatively affected by poor temperature control, so keep a close eye on this (even with T5s).

All in all, T5 lighting is a great addition to any grow room. These fixtures may not be quite as powerful as high-intensity lights and they may not be as efficient as LEDs, but T5s still have a lot going for them.