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How To Choose Fluorescent Grow Lights For Your Grow Room

Growpackage Eco Farm
Sep 27, 2019 · 7 min read

Using Fluorescent Grow Lights in your Indoor Garden

Options for fluorescent grow lights were limited for many years. The standard 2 bulb, 4 foot long fluorescent shop light was just about your only choice. Because of the affordability of the fixtures and the huge improvements in the bulbs themselves, standard fluorescent lights are still an excellent choice.

Is fluorescent light good for growing plants?

Fluorescent grow lights are best kno w n for their propagation abilities. These lights do wonders for clones, seedlings, and young plants, since they have low heat output and a less intense light. HID and LED grow lights need to be placed further away from plants, and a lot of light is wasted. Fluorescent tubes are smaller, and save the grower money on electricity costs. These lights can also emit a full spectrum for plants.For growers trying to grow the biggest plants possible, fluorescent lighting is a great way to get plants started. Once the plants begin to get larger, it is best to switch to a CMH or LED grow light to increase yields come harvest.

Fluorescents are best for when you don’t have a lot of space.

There are times when the cannabis growing world moves slow, and then other times it changes overnight. The latter is the case for fluorescents, and you can thank LEDs.

Fluorescents are best for when you don’t have space to grow in. But in the last couple of years, high-quality LEDs have been split into rows or strips which can get them within 12in of the plant’s canopy without causing light burn. LEDs grow much bigger plants and can make up their initial cost within the first grow.

Fluorescents, particularly, the T5 Bulbs, can grow some wonderful cannabis and can pull anywhere from one to five ounces with the average indoor setup.

Why Grow With Fluorescents

The biggest benefit to fluorescents is they’re great if you want to run a single grow just to see if growing cannabis is for you. You likely won’t have the CFLs you need lying around (20+ true watts), but it’s easy finding uses for them around the house if growing isn’t your thing.

Pros of Growing with Fluorescent Lights:

Easy & cheap for first-time growers to put together

Low to medium heat output

Perfect for seedlings when using HIDs for later stages

Great for small spaces

T5 & T8 bulbs can often compete with blurple LEDs

Tips For Fluorescent Grow Lights

Growing Tip 1 — You’re going to want your CFLs within an inch or two of the plant’s canopy. Just make sure they don’t touch the plant as they will burn them. The T-series lights need to hang a little higher (8–12 inches), so you’ll need to watch for light burn like you would with HIDs or LEDs.

Growing Tip 2 — When calculating your wattage for CFLs you need to ignore the “equivalent wattage” and look for the true watts, which will be the lower of the two numbers.

Growing Tip 3 — Expect to only grow one plant at a time. While you won’t need a large ventilation system like you would with other lights, you’ll still want fans near the grow space to remove heat build up.

When should you use fluorescent grow lights?

Most large-scale and commercial operations use LED lights because they last longer and emit more light. Fluorescent bulbs are also more fragile, meaning a farmer can incur additional labor costs to maintain them, and that may not be worth the time or money.

However, the small-scale or hobby farmer may find fluorescent lights to be an economical choice, especially for low-light plants or plants at a low-light stage of development.

To make the best economic decision about lighting for your farm, compare both the capital and operational expenses of your lighting options over time. (For example, this is how HID and LED compare.) Don’t forget to factor in replacement and heat-removal costs! Another option to consider is LED light bars.

Choose a high-output fluorescent

All fluorescent lights work in a similar fashion:

An electric current heats up gas inside the tube, which emits ultraviolet light.

Meanwhile, a phosphorus coating inside the tube turns that ultraviolet light to visible light.

A ballast on the back converts the incoming electrical current into a usable form.

You’ll see several numbers on a fluorescent light that give you information about how it works, and help you avoid lights that are too dim.

Tubular lights have a “T” rating that tells you the diameter of the tube. T12 lights have that designation because they have a diameter of 12/8 of an inch or 1.5 inches. These tubes were commonly used in indoor lighting applications, but they’re just not very bright, even with a coating to make them full-spectrum.

T5 lights are narrower than T12s, with a diameter of 5/8 of an inch. Look for a T5 bulb with an additional “HO” rating, which stands for “high output.” That means the ballast has been adjusted to make them even brighter — and for growing purposes, more efficient.

“This is the preferred [fluorescent] light that we use. This is a very high output light. If you put a T5 next to a T12 and turn them on, you will absolutely see the difference,” Dr. Nate Storey says.

When buying a full-spectrum grow light, you also need to look at the Kelvin rating, which indicates how warm the light is. Fluorescent lights, in general, tend to be bluer but look for a light ranging from 5,600–6,400 Kelvin, which will be indicated on the bulb. On the lower end of that spectrum, the bluer light will give you stockier growth, while the higher rating is great for any kind of vegetation.

Fluorescent lights will also come with a wattage rating to tell you how much electricity the bulb uses, usually 54 watts.

This is the newest improvement to fluorescent grow light systems. The T5 system uses improved high output bulbs, like the ones I suggest using in the section above. They use several bulbs side by side, and there is an arched reflector behind each bulb. These lights are designed to support bigger plant growth. Their best use is for growing strong, healthy plants up to 24 inches tall in the vegetative state. T5 lights are a little expensive in my opinion, so I recommend sticking to standard fluorescent shop lights for your seedlings and clones.

One friend who has been using T5 fluorescent grow lights exclusively has told me these lights support flowering well. However, he also told me the yield is about half what you would expect from the same size garden grown under a high pressure Sodium light of the same wattage. After gardening under fluorescent lights for a year to save money, my friend is now switching to a high pressure Sodium grow light.

Choosing the Right T5 Grow Lights

To use T5 grow lights properly, there are a couple of things you need to know that will determine how successful you will be at growing under these lights. The first thing is how to choose the right T5 fixture and the right bulbs.

Fixtures: When it comes to choosing a grow light fixture, there are a couple of things to think about. First is the size requirements for this grow light. There are more than a dozen size variations, so you need to figure out the size of your indoor garden and then fit the lights to your space. T5 grow lights typically come in two different lengths and around six different bulb configurations. The most common T5 grow lights are 2- or 4-ft. long and have 1, 2, 4, 6, 8 or 12 bulbs per fixture. If you are thinking of growing only a few small plants, you might get away with having a 1- or 2-bulb set-up that is 2- or 4-ft. long, but if you want to grow a whole bunch of plants, you will have to invest in an 8- or 12-bulb set-up that is 4-ft. long. This larger size will cover a lot of plant mass without using too much electricity.

Bulbs: When it comes to choosing bulbs, there are even more options to choose from. Bulbs not only come in different energy varieties, but also in different color temperatures. When choosing between normal output (NO), high output (HO) and very high output (VHO) bulbs, I recommend going for the middle ones. HO bulbs are the best of both worlds — they are efficient, yet long-lasting, and will provide super-bright light for your plants.

As far as color temperatures go, different plants have different light requirements, so I can only suggest a general guideline, which is to start with 6,500 Kelvins bulbs when plants are in the vegetative stages of growth. This is approximately the color temperature of light on a summer day. Otherwise, use 3,000 K bulbs when plants start to flower. This color temperature is warmer (more sunset-like), with a red tint to it, so it will best suit blooming plants.

Options for fluorescent grow lights were limited for many years. The standard 2 bulb, 4 foot long fluorescent shop light was just about your only choice. Because of the affordability of the fixtures…