A few years ago, growers usually only used fluorescent tube lighting as a supplemental light for cannabis plants, or for young seedlings and clones only.
With the new high output lights such as the T5, fluorescent lights can be used until the plants are about 24 inches tall, which is just enough to grow a very short plant through to the flowering stage when you control your marijuana plant's growth through the vegetative stage.
However, you can use either type of lights during either stage and still get good results. People also use "Daylight" (5000K) bulbs with success.
T5 fluorescent tubes come in different shapes and sizes but the typical sizes are
The T5 tubes can have a luminous efficacy of up to 100 lumens per watt and that means that you can grow your plant with less electricity! If you are growing a decent amount of autoflowering plants under a 200W and 24 hour light cycle of fluorescent lights then (if electricity costs 10 cents for a Kw/h) you would be paying 48 cents every day ((200W*24H)/1000)*0.10$) or about 15 $ every month.
T5 light sizes & shapes
With these 15$ you can grow a decent yield compared with T8 – just look how more efficient the T5 tubes are:
High output T5 tubes are basically the same as the regular T5 fixtures but they have higher lumen output and higher input currency that make them more usable to cannabis growers but that also makes them more inefficient! These HO bulbs usually have double Watt input and almost double-lumen count but they also need special ballasts so you can’t fit a High output fluorescent tube in a regular T5 socket! If you are considering T5 lights for your autoflower or regular cannabis grow you should know that these High output bulbs are the most common used T5 grow lights but you can grow weed with regular bulbs more efficiently! With T5HO bulbs you won’t get that 100 lumens per watt but you can get up to 80-90 lumens per watt and in the long run you will lose some money but you will need fewer bulbs to illuminate the same amount of autoflowering plants!
Fluorescent light penetration
So now that we know that light penetration is not different from any light source if they match in lumen output, we need to know how intense is a T5 grow light and what is its spread? Autoflowering cannabis growers should know that fluorescent tube light has small intensity but a large spread whereas the HPS has high intensity and small spread.
The best height for a T5 grow light is about 6-8 in. above the plants, but you should increase that gap to 12 in. if your plants don’t like heat or they are in the seedling growth stage. If the T5 fixtures are at this height, the light from the bulbs will be intense enough and bright enough for plants, but the heat won’t be able to damage your plants. Some plants need less-intense light, so just monitor your plants and see what works for your indoor garden set-up.
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.
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.
T5 fluorescent grow light fixture. – B Brown / Shutterstock
T5 fluorescent grow bulbs. – preedee anantuntikul / Shutterstock
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.
Setting Up the T5 Lighting System
Light cycles tend to differ based on what plants are being grown under artificial lighting. For example, there are 12/12-hour cycles, 18/6-hour cycles and even 24/0-hour cycles of light/dark periods. To find the right cycle for your plants, I suggest either researching the needs of the variety of plant you’re growing, or basing your cycle on what the approximate light cycle would be if the plants would be growing outdoors during their season. Typically, more light means faster growth, which results in bigger plants and bigger yields no matter what you are growing.
Many indoor growers are already familiar with the virtues of T5s, but even if you know your T5 fixtures and more or less know how they work, you might need help with some things, because specifics like color temperature, hanging height and light cycles might not be as easy to figure out.