The biggest problem with fluorescent tubing is that the light that they give off is only useful for about a foot or so. That's why they're kept so close to your plants.
For flowering, choose bulbs that are "Warm White" or "Soft White" colored (usually labeled as "2500K" or "3000K").
However, you can use either type of lights during either stage and still get good results. People also use "Daylight" (5000K) bulbs with success.
The great thing about fluorescent grow lights is that they don't get very hot, and they can usually be kept 1-4 inches from the tops of the plants at all times without having to worry about burning your cannabis leaves or buds.
Now that you have selected the right fixture and bulbs, it is time to set up your grow lights. The first thing you need to think about when setting up T5 grow lights is the height, or how high above plant canopies you are mounting your fixtures. Although T5 lights are famous for emitting very little heat, this doesn’t mean you can put the bulbs an inch above plant canopies, as this distance will still damage the plants.
T5 fluorescent grow bulbs. – preedee anantuntikul / Shutterstock
First things first, for those of you who do not know the basics, a T5 grow light is a tube-shaped fluorescent light that is 5/8-inch in diameter. In terms of the light’s name, the “T” is for tube shape, and the “5” is for the 5 in the 5/8-in. unit of measurement.
Setting Up the T5 Lighting System
T5 fluorescent grow lights are energy efficient and provide consistent levels of light to all of the plants within their reach. Whether you’re already up and running with your T5 fixtures, or are just starting out, this article contains helpful advice.
You are almost ready to go—all that’s left is figuring out the right light cycles, and then you can turn on your lights and start growing. A light cycle refers to how many hours you keep the lights turned on for and for how many hours you leave your plants in the dark. Light cycles are used to simulate night and day. Outdoor plants get a certain amount of hours of light and dark to grow properly, and you need to simulate these conditions indoors, too.
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.
Different durations of light and darkness will affect how plants grow, whether they bloom or not, and other elements. – StephenVanHove / Shutterstock
Just wondering if you would use a T5 to flower a pot plant? – Raymond M.
Yes, you can use a T5 fluorescent light to flower a pot plant. The benefits of using this type of lighting is the lack of heat that they generate. Because they’re not super-warm, you can place your plant tops within just a few inches of the light. The disadvantage of flowering under fluorescent lighting is the lack of light intensity and penetration. This makes the Screen of Green (ScrOG) method ideal as you can train the flowering tops to create a level canopy close enough to the light.
T5 Fluorescent lights over motherplants.
My recommendation, however, is to grow under High Intensity Discharge (HID) lighting such as High-Pressure Sodium (HPS) or (Metal Halide) systems. Although they run much hotter and use more electricity, they produce plenty of light for plants to thrive and build thicker flowers. If you’re interested in a bigger yield from increased light and can handle the added heat, HID lighting is ideal for indoor marijuana production.