Fluorescent Grow Light FAQ
1. Why buy fluorescent grow lights?
Compact fluorescent grow lights (CFL)s are perfect for people who just want to grow a plant or two for personal use or to give growing a try. They are also great as supplemental lighting to fill in areas your main lights aren't fully reaching.
Fluorescent tube lighting (T5 grow bulbs) can be used for more plants, but is not generally powerful enough for flowering a larger grow.
Here are the main pros and cons of fluorescent lighting:
Advantages of fluorescent grow bulbs
- minimal space requirements—this makes them perfect for small, stealthy grows
- cheap setup cost—it's really easy to get started with fluorescents
- can be bought anywhere—unlike HID and LED lights, you can find fluorescent lights anywhere
- low electricity use and low heat output (naturally, this will increase as you get more and bigger bulbs)
- great way to try out growing
Disadvantages of fluorescent lights
- only make sense for very small grows (a bit larger for T5)
- only work with short plants
- less efficient than other lights—fluorescents are great if you only use a few bulbs, but once you start expanding, they actually produce less output per wattage and give off a lot of heat
- need a lot of bulbs and sockets—if you want to expand, you'll need a lot of bulbs and a separate socket for each one
- need constant adjustment—fluorescent bulbs need to be very close to plants to be effective, but can not touch the plants, so you have to constantly monitor and adjust
2. What's the difference between CFL and T5?
CFL stands for compact fluorescent light and is basically the types of bulbs you may have already have in a standard light fixture in your house (the energy-saving ones). Use CFL grow lights as supplemental lighting or for a small, stealth grow in your closet, etc. We also have some small CFL grow light fixtures for sale that can be useful to focus the light onto your plants.
T5 are fluorescent tubes, like the ones you probably have in your office. There are also T8, T12, etc. bulbs, but we only have T5 grow lights for sale on this site, since they are the only ones you should use for growing. Use T5 lights for a larger grow of short plants or a small grow that's a bit bigger than the "stealth grow in a closet."
3. What type of bulbs do I need?
All the fluorescent bulbs on this site are labeled as either "veg" or "flowering" and give off the ideal color temperature for that purpose. This makes choosing a bulb easy.
If you prefer to buy fluorescent grow bulbs at a Home Depot, etc. look for bulbs with a color temperature around 2700 K (sometimes also labeled as "warm white" or "soft white") for flowering and 6500 K (also labeled as "cool white" or "cool") for vegging.
Getting both temperatures is ideal, but you can use either bulb type for either purpose, if necessary. If you only get one type, you're better off getting the 2700 K bulbs.
Another option is to go with 5000 K daylight bulbs and split the difference, but you will get the best results using both 2700 K and 6500 K bulbs.
"High output" bulbs are preferable, as they provide more light for your plants. All the bulbs sold on this site are "high output."
4. How many bulbs do I need?
If all the green leaves are brightly lit, you have enough bulbs. If you see any shadowy areas, you'll need to fill them in.
5. How far from my plants should I hang the bulbs?
Fluorescent bulbs can hang mere inches from your plants without burning them. In fact, if they get more than a foot or two away, their light becomes too weak to be much benefit.
Hang the lights close and test the heat by holding your hand palm down above your plants. If it is too hot for your hand, it's also too hot for your plants and you need to back the lights off a bit.
6. How many plants can I grow with fluorescent lighting?
If you use CFL bulbs for growing, one or two small plants is the maximum. With T5 bulbs, you can grow as many plants as you want during veg, but T5 tubes will not produce the best results during flowering, especially if your plants grow larger than 2 feet tall. At this point you need to either supplement with other lights or just switch to HID or LED.