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T5 vs. T8 Grow Lights – The Light Guide for Indoor Gardening

When growing indoors, you have a lot to consider. There’s humidity, temperature, soil, etc. – and this can be even more complicated if you’re working with hydroponics. One of the most significant considerations is your grow light, and indoor growers always ask about T5 vs. T8 lighting. In this article, we’re looking at the differences between these two options, so you can decide what’s best for your indoor garden.

Choosing the right indoor lighting source can mean the difference between a thriving garden and a disappointing one. A grow light is a multi-purpose light bulb that mimics the energy and influence of UV rays or sunlight exposure on plants at all stages of their development. This light allows users to cultivate plants indoors or in regions with unideal weather.

While most artificial alternatives to sunlight are not prohibitively expensive, choosing the incorrect one could waste time and effort for indoor growing. Accordingly, it’s critical to compare the T5 and T8 grow lights to determine which is best for you.

So, what are the most significant differences between these two technologies? Which one is better for your garden? We’ll consider some of the most crucial factors and differences between these options to make an informed decision on which one to buy.

Factors To Consider When Purchasing A Grow Light

There is a wide range of light qualities out there. Below are the primary considerations for indoor growing.

  • Initial Cost – the cost of the bulb, the fixture, the setup, and accessories
  • Longevity – how long the bulb lasts
  • Life-Time Cost – the overall cost of purchasing and running bulbs, longevity, and quality of light
  • Energy Efficiency – the amount of energy used to run the fixture and light
  • Color Temperature – whether blue light, red light, or anything else on the spectrum
  • Light Output – the amount of light produced
  • Light Received – the amount of light that the plant can absorb
LED grow lights

Why Is Comparing Grow Lights Difficult?

Grow light companies and distributors use a lot of fluffy language to market their products. You’ll see words like lumens and light intensity used, as well as acronyms like PAR, PPF, and PPFD.

Here’s what some of these definitions and acronyms mean:

PAR Vs. Lumens

It’s easy to overlook the fact that plants and humans have incredibly different perceptions of light. Humans use photopic vision to sense color, which is measured in lumens. Photosynthetic active radiation (PAR) is the light wavelengths that drive photosynthesis in plants.

PPF: Intensity Of Light

PPF (Photosynthetic Photon Flux) refers to the total amount of light produced per second by an LED, T5 bulb, or other light sources. This is what we refer to as the intensity of the grow light. The unit of measurement is micromoles per second (umol/s).

PPFD: Measurement Of Light Received

The photosynthetic photon flux density (PPFD) is used to measure the quantity of PAR that travels from your fixture to your plants. In other words, this is a measurement of the PAR emitted by the lighting fixture at the plant.

What Are The Different Types Of Light Available?

There are several grow lighting options, but they are typically divided into a few different categories.

Ceramic Metal Halide Lights

This option is under the high-intensity discharge umbrella and creates light when an electric current passes through metal halide gas and mercury. It is known for having a high-quality light emission 3-5 times more efficient than incandescent lights. That said, they take a long time to heat up, meaning you won’t have your light immediately, as in the case of options like LEDs.

High-Pressure Sodium Lights

HPS systems were the industry standard for a long time because they were cheaper, had a higher intensity, and produced a lot of red light.

They also emit a lot of yellow light, which is why they’re widely used for street and security lighting. For many years, HPS lights were preferred by indoor and greenhouse growers because of their large outputs and broad color spectrum.

Incandescent Lights

This is the old-timey option that requires electricity to run through a filament, heat it, and produce light. This is the one you can thank Edison and Swan for making.

For anyone reading at home, you probably don’t need an incandescent grow light. There’s still plenty of healthy debate between which lighting is best for indoor growing, but I don’t know of anyone who still thinks incandescent lights are a viable option. And while products under the LED umbrella improve every year, the incandescent light is just flickering into obscurity.

Fluorescent Grow Lights

Fluorescent lighting is an umbrella category over CFLs, linear fluorescent tubes, T5 bulbs, T8 bulbs, standard T12 bulbs, etc. This versatile lighting option is used in stores, schools, offices – and sometimes indoor gardens. To produce light, electricity enters the fluorescent fixtures through a ballast, feeding into the metal pins on both ends of the fixture. As the electricity flows through the tube, the gasses react and produce light visible to the human eye. Fluorescent tube lights are cheap to purchase, pretty compact, and more efficient than incandescent bulbs. T5s are specifically known for seed starting.

Also read: 59 AeroGarden Tips and Reviews For Instant Success

LED Grow Lights

LEDs are the up-and-coming stars of the grow light world. They’re practical, energy-efficient, and becoming more affordable by the year. LED lights are made up of two semiconductor materials, one charged positively (protons) and the other negatively (holes) (electrons). When these two particles collide, energy in the form of a photon is emitted. The quantity of energy released determines the color of the light. After that, the light is focused and cast in a specific direction. LEDs are known for producing a lot of light, specifically full-spectrum light.

Want to see how LEDs compare? Check out our LED Grow Lights Vs. HPS article here.

LED Best Seller List By Value

T5 vs. T8 – The Best Grow Light for Indoor Gardening

T5 and T8 lamps can be the primary illumination source for your plants or merely as supplemental options. Both lights have advantages and disadvantages, making it challenging to determine which is best for your situation. Before you choose, make sure you know what you want and need.

T5 vs. T8 – What’s the Difference?

For starters, T8 bulbs have a diameter of eight-eighths of an inch (equivalent to 1 inch). The is what the “8” in its name means.  T5 bulbs, as you might have guessed, are five-eighths of an inch thick, making them the thinner option. Because the two tubes are not interchangeable, this is a crucial consideration when looking at the fixture you want over your garden.

T5 and T8 tubes are available in various color temperatures and lumen outputs. Suppose you’re looking for fluorescent tubes to use in an office devoid of natural light, for example. In that case, you’ll want to choose one with a lower lumen output, a warmer color temperature, or both, depending on the environment. Excessive light output or a color temperature that’s too cool can harm your plants and limit their growth.

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T5 or T8 Grow Lights: Which Is Better?

T8 grow lamps are preferred by many indoor gardeners because they provide more overall lumens, have a longer life, and are more efficient than standard fluorescent bulbs. However, T5 high-output bulbs have an even more significant advantage in being roughly 9% more efficient than T8 bulbs, allowing them to generate more light in a smaller space while using less wattage (75 to 90 lumens per watt). T5 also has a high color rendering index (CRI), making them more visually appealing.

Light Spectrum & Wavelengths

While many of the best grow lights give off the full spectrum, others primarily produce a blue or red spectrum light. The ranges of the T5 and T8s are relatively similar to one another and are equally customizable. T5 and T8 have nearly identical color rendering, which means they have very similar spectrums. However, because the T5 is brighter than the T8, the extent to which the plants can receive the entire light spectrum may vary.

Bulb Quality & Intensity

The T5 has a better lumen-to-watt ratio than the T8, implying that its output is more efficient and brighter per watt of energy used. Another feature that makes the T5 the ideal light for performance is that the illumination is more focused and concentrated in a single spot due to its smaller diameter. While T5 lights are brighter and more potent than T8s, they can cause significant glare while over-stimulating the plants.

Heat Output & Temperature

Because the heat emits from a broader area, the T8 grow light is cooler and safer to touch than the narrower T5 grow light. Accordingly, plants are more likely to be damaged if they touch a T5 bulb than a T8 bulb. When it comes to temperature, keep in mind that T8 performs best at 28°C (82°F), while T5 performs best at 35°C (95°F).

t5 light with plants

Fixture Lifespan & Efficiency

The T5 generally has a longer lifespan and experiences less deterioration than the T8, which is more sensitive to frequent on and off switching. However, if you leave the grow lights on all the time–– which we don’t recommend–– both should last the same amount of time. They’ll both last roughly 36,000 hours if you use the 12/12 light cycle (12 hours on, 12 hours off). The T5 also has a better lumen-to-watt ratio than the T8, meaning its output is more efficient and brighter per watt of energy used. 

T5 Grow Lights may be found at most hardware and specialized stores like Home Depot, as well as nurseries, and can cost anywhere from $10.00 to $200.00. In terms of life expectancy and wattage, the higher-end models appear to have more favorable consumer evaluations, while the lower-cost models are more budget-friendly for new gardeners.

Size Options & Customization 

T5 lights have a diameter of five-eighths of an inch. T8 light bulbs are 40 percent larger, with a diameter of one inch– or eight-eights. A T8 grow lamp is about the same size as a nickel, while a T5 model is around the size of a dime. The T5 then is more compact than the T8. Regardless of size, the ranges of the T5 and T8s are relatively similar to one another and are equally customizable. 

Price Considerations & Limitations

Generally, T8s are a little less expensive than T5s. Because of the T8’s shorter lifespan caused by frequent on and off switching, you’ll have to replace it more frequently and, in turn, spend more money. Over time, T8s will become more expensive than T5. Note that if you plan to install the T8 in a location that demands light 24 hours a day, it will be cheaper in that it will last about as long as the T5.

T5 vs. T8 Grow Lights Guide

Whether you’re a novice or a seasoned grower, a grow light can provide numerous benefits to you and your garden. With its rays and warmth, a grow light will assist your plants in flourishing from average to excellent quality and higher yields. T5 and T8 grow lights will help you reduce the chances of losing a plant to poor weather conditions while also improving your garden’s durability.

What’s the T?

Fluorescent lights, also known as fluorescent linear tubes, are classified based on their wattage, shape, and diameter. The “T” in T5 signifies that the bulb is tubular, and the “5” indicates that it is 5/8 inch in diameter. The larger T8 (eight-eights, one-inch) tubes are also popular. The T is simply a code that indicates the bulb’s shape and output. It specifies the level of energy efficiency as well as the diameter of the lamp tube.

How Much Light Do T5 & T8 Lights Put Out?

The lumen output capabilities of T5 versus T8 bulbs is another feature that distinguishes them. A regular 4′ 54-watt T5HO linear tube, for example, will typically produce around 5000 lumens per tube, whereas a standard 4′ 32-watt T8 light will generally have about 3000 lumens per tube. When weighing the advantages and disadvantages of the two tube options, keep in mind your garden’s lighting requirements. If you don’t need as many lumens, the lower-wattage T8 is a better alternative because it uses fewer lumens and consumes less power. If you need a higher level of illumination, the T5 may be the better choice for you.

How Many Light Fixtures will I Need?

Answering this question is dependent on the amount of space available in your grow area. However, a good rule of thumb is to get T5 or T8 (or both!) fixtures that are the same size as your grow room ceiling height. When you have an 8×8 grow area, you should consider getting two 2×4 fixtures to fill the space. ​

Are T5 Tubes Being Phased Out?

Have no fear – T5 fluorescent tubes are still being produced. That said, because switching to LED lights can lower energy costs while maintaining relative efficiency, it’s not a stretch to think that T5s and other fluorescents could one day be removed from shelves. The UK government, for instance, is planning to remove fluorescent lights from stores in September 2023 to combat climate change.

Can I Replace a T5 with an LED Grow Light?

You can simply switch your T5 fluorescents with LED tubes designed to work in the same system. Doing this can cut your energy prices by as much as 50%.

Do I Need a Grow Room?

Grow tents are a good idea for controlling variables, including light, water, temperature, and humidity. With the reflective material, grow tents can help you maximize the efficiency of your grow lights, as well. While not necessary for everyone, grow rooms or grow tents make an excellent option for indoor growers.

T5 vs. T8 Grow Lights – Everything You Need to Know

The T8 tube, like the T5, uses electrical circuits to produce light and is available in standard 2, 3, 4, and 5-foot lengths. T5 fluorescent lamps, on the other hand, are distinguished from T8 bulbs by their significantly smaller size. T5 tubes are 40% smaller than T8 fixtures, but they can provide just as much, if not more, light in the same amount of space. More T8 fixtures are required to produce the same amount of light as fewer high-output T5 bulbs. T5 lights are more expensive than T8 lights, though they require less maintenance than other fluorescent bulbs. When paired with the T5 bulb’s capacity to deliver more light (lumens) than other bulbs, your garden fixtures will save money in the long run.

Benefits of T5 Grow Lights

T5 lights are efficient, they last a long time, and they don’t produce much heat. More specifically, the T5 grow light takes the lead over the T8 grow-light in terms of efficiency. The T5 has a higher lumen to watt ratio than the T8, which means its output is more powerful and brighter per watt of energy. The T5 is also more efficient because its light concentrates in a single spot because of its smaller diameter–– more watts per cubic centimeter. Its energy efficiency also translates to a longer life-cycle, meaning less maintenance and replacement for you. Lastly, its smaller size and better efficiency result in lower overall temperatures.

There are many T5 options out there, but here are a few options to get you started.

Benefits of T8 Grow Lights

When we consider the actual quality of the light, the T8 is often the superior lamp because it has less glare and is, therefore, more effective in household usage and sometimes similarly for plant growth. The T5 light is brighter and more potent than the T8, though the glare can misdirect its wavelengths. At the very least, the T8 may be the more visually appealing option. T8s also have the slight advantage of a marginally cheaper upfront cost.

Downfalls of T5 Grow Lights

T5 lights, despite their higher efficiency, necessitate more expensive fixtures. Another disadvantage is that those fixtures may have shorter life expectancies to accommodate the higher output, often charting roughly 10,000 hours compared to T8 tubes’ average of 30,000 hours. And, if the lights are hot, the T5 bulb, as opposed to the T8, is more likely to damage your plants if they make contact with each other. Again, because the T8 bulb generally creates less heat wider heat distribution, your plants can be nearer to it and remain comfortable. It’s important to note, though, that the T8 bulb isn’t entirely cool; it’s impossible.

Downfalls of T8 Grow Lights

Depending on the size of your indoor growing project, the cost of energy efficiency (or lack thereof) in utilizing T8 bulbs can rise significantly, so it’s best if you choose more energy-efficient lighting solutions. With that in mind, T8 grow lights are acceptable for the early stages of growth when your setup is relatively small. Their reduced illumination capacity can stifle and inhibit growth during the blooming and vegetable stages of more extensive gardens but are more than sufficient for a plant or two.

When Should I Use T5 Grow Lights?

When it comes time for the vegetative and flowering phases, T5’s are about 12% more efficient.

The best T5 grow lights are generally ideal for plants about to flower since they require more intense light and provide more watts per cubic centimeters. Another argument favoring the T5 for flowering is that since T8 bulbs are less severe, you’ll need to place them closer to your plants to achieve the same results as T5. In this case, T5s are lower-maintenance.

When Should I Use T8 Grow Lights?

For use in cloning, seeding, and rooting, T8s might be your best bet. Gardeners also tend to utilize the T8 for cuttings and seedlings. Apart from horticultural applications, aquarium owners are primary users of the T8 bulb. Regardless of how growers commonly use these lights, they may help stimulate plants in a commercial or domestic setting while giving excellent supplemental lighting in greenhouses.

Types of T5 & T8 Lights


T5 fluorescent lights are worth highlighting mainly because they are by far the most common form of a T5 fixture used for indoor gardening. Many gardeners have moved away from more powerful lighting such as HPS bulbs (high-pressure sodium) or MH to the more efficient T5 fluorescent lights. Fluorescent T5 and T8 fixtures can also keep your initial costs low if you’re just starting off sprouting plants indoors. You shouldn’t necessarily buy the cheapest lights available but instead, get the best quality your budget allows. The T5 will still be less expensive than most other lighting solutions. ​


Some growers use LEDs and incorporate them into a T5 or T8 system, which is totally doable. You can buy LED tubes to replace your T5 lighting fixtures and convert your entire system to LED. The advantages for LED options, in this case, are the same for an LED light in general: Less energy consumption, low-temperature output, and an exceptionally long life span. However, if you choose T5 or T8 LED bulbs over fluorescent lights, you’ll face the same problems as you would with any other LED bulb. Also, double-check that the model you’re using is compatible with LEDs!

vertical indoor garden with GE grow lights

Fixture Features to Look For


T5 light bulbs and T8 tubes have consistent diameters (5/8” and 8/8”, respectively), but the size of their fixtures will vary, providing you with versatile options for your grow room. You can get just about any length and quantity of bulbs you want or need. When picking which to buy, think about how much space you have in your indoor garden. If you don’t need some of the bulbs, you can quickly turn them off. You can’t, however, turn on bulbs you don’t have!

Bulb Temperature

Most growers use fixtures with 6500K bulbs because many commercial farmers employ these lighting systems to harvest microgreens, seedlings, and plants in their vegetative state. However, in a T5 or T8 system, you can produce flowering and fruiting plants all from the same setup. You’ll also need to consider 3000K lights for the more delicate phases of growing, and they often come in five-packs with two-foot and four-foot lengths.

Reflector Style

The reflector is a significant component in the T5 bulbs’ superior performance over the T-8.

Consider a ray of light coming from the bulb: it’s pointed up toward the reflector, away from the plants. A simple flat mirror reflects the beam of light from the bulb directly back at itself, while good reflectors often have an indentation directly above the bulb that reflects the rays sideways around the bulb and down onto the plants. A reflector can redirect the light “spilling” out of the sides of your grow room.

Furthermore, there are two primary grow lamp styles: rectangular reflector and gull-wing reflector. You can utilize encased mirrors and set your lights closer to your plants for the best light coverage, but you can use the gull-wing type if you need to put suspend them further from the garden. 

Extra Features

Keep an eye out for added features that will help you get the most out of your T5 and T8 lights. The most important is the ability to manage bulbs separately, either by dimming or using switches that turn off some lamps while leaving others on. With these capabilities, you may save electricity by providing plants with the light they require to flourish. Such customization is beneficial for starting seedlings because their light requirements are so low compared to those in the vegetative phase of a bushy plant.

Additional Considerations

The Size of Your Grow Room

Measure your growing area to determine the best lighting system you can fit before you consider buying new grow lights. You may need to purchase additional units and stack them side by side to get the most coverage, depending on the size of your room. Because of your grow room setup, one single unit may not be enough to provide the coverage you require.

Your Budget

Choosing between a T5 or T8 fixture will be considerably more straightforward once you’ve determined your color temperature and lumen output requirements, as well as your budget.

T5 grow lights are pretty inexpensive compared to other types of lighting. It’s simple to start gardening with T5 lamps in particular, but adding more will add to the cost, so do your research before committing.

Your Existing Lights

If you currently use grow lights, think about how adding T5 or T8 lights can enhance your arrangement. Unless you plan to replace your existing lights entirely, you should calculate all your lights’ overall energy cost and light output before purchasing anything more.

The Color Temperature of the Bulbs

Because T5 light bulbs are replaceable, double-check what your system includes. Fluorescent fixtures thrive in the vegetative stages of growth, so you should always use bulbs suited for them. However, don’t be frightened to bring up some flowering bulbs.

The Manufacturer

The manufacturer counts a lot, as it does with many other types of indoor grow lights, or any product, for that matter. Use established brands with a good history and authority in the gardening world. There’s a lot of competition in the space and every manufacturer wants a piece of the pie– avoid unidentified knockoffs.

What You’re Growing

Once you’ve got the light bulbs, what are you going to grow? If you want to cultivate huge fruiting plants, you’ll probably need to increase your size and power needs. T5 grow lights are ideal for seedlings, microgreens, and any plant you harvest before flowers. For use in cloning, seeding, and rooting, T8s are your best choice. 

What about T12 lights?

You may have heard of another similarly named lighting. Gardeners used to choose between T5, T8, or T12 fittings for your garden in the not-too-distant past. As you may have guessed, they were twelve-eighths of an inch in diameter, or more simply, an inch and a half. Different technologies develop, however, and things change– including lighting options. T12 bulbs are an older model of fluorescents, and because the fixtures are so inefficient compared to competing technologies, the United States Department of Energy banned their production in 2012. While new T12 bulb fixtures are no longer available, you might still find them in used markets and existing gardens. Though I’m not sure why you’d want to look for them; they’re terrible.


There are so many light bulbs and fixtures to choose from in the indoor grower space. Two of the most traditional options are the T5 and T8 fluorescents. 

The main difference between the T5 and T8 Grow Lights is the diameter of the fluorescent tubes. T5s are 5/8″ in diameter, while T8s are 1″ in diameter. Also, T5s are slightly shorter than T8 fluorescent tubes. This is an important note as it means it could be difficult to swap out T5s and T8s on the same fixture. T5 lamps are smaller and more efficient than T8 bulbs.

T5 lights are the winner between the two, they do cost about 2x more than T8 options. While T8s are cheaper upfront, T5s are a more affordable option long-term and are great for most growing needs.

Get started with your indoor garden and purchase a grow light today.

If you need help hanging a new set of artificial lights, and happen to live in the Chicago area like us, consider calling Fix It People to take care of it for you!

One thought on “T5 vs. T8 Grow Lights – The Light Guide for Indoor Gardening

  1. Hi Brent,
    Are T5HO grow lights different from T5HO lights. Because if they are I can’t seem to find them.

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