Fluorescent Lights are up to 7 times more energy efficient than incandescent, they use substantially less energy and operate cooler than metal halide or HPS grow lights.
Fluorescent Lamps are also available in a wide spectrum range. Fluorescent lights are a popular choice among small gardeners due to their low price, availability, compact size, low heat emission, and smaller electric bills.
Advantages and Disadvantages of Standard Flourescent Lights for Indoor Plants
Fluorescent bulbs however, are not ideal for large plants, as they do not penetrate as deeply as High Intensity Discharge lamps. Fluorescent lamps may be a viable option for growing large plants only if you have many more lights above and to the side of the plant. A lot more lights throws off the equation of energy efficiency and cost effectiveness.
Some growers find that fluorescent lights are perfect for use with seedlings and cuttings as well as for use with other plants that do not require the high intensity of H.I.D. (High Intensity Discharge) lighting.
Light intensity dramatically affects the quality and yield of plants. If you lighting is sub optimal your yield will be vastly diminished.
A typical indoor hydroponic garden will need 20 to 40 watts per square foot.
Seedlings require a bare minimum on the average of 15 to 20 watts per square foot.
Leafy house plants 15 to 20 watts per square foot - minimum.
Lettuce and leafy edibles require about 25 watts per square foot.
Tomatoes, Peppers, Cannabis about 40 watts per square foot..
Standard fluorescent lights, spaced a foot apart will only supply approximately 10 lamp watts per square ft.
In addition to only supplying a portion of watts per sq. foot necessary, another disadvantage of fluorescent lighting is that the light intensity decreases the farther away the light source is from a plant..
The lights rated capacity also shifts depending on orientation, the rated capacity is only measured form the light source, the bulb, in a straight line - right on down to the plant. If the plant is not directly below the light source, intensity diminishes and the equation shifts..
To be effective a standard fluorescent light would need to be only a few inches from the plants top. As plants are growing organisms this distance will be continuously changing. Adjustable height lights are advisable.
Compact Fluorescent Lamps (CFL)
Compact Fluorescent Lamps (CFL) are a relatively new form of fluorescent bulb. They include those spiral shaped energy efficient light-bulbs which are quickly replacing incandescent bulbs for household lighting. They are cost effective and useful for smaller hydroponic projects. They don’t require professional wiring or a ballast, simply a socket to screw them into - same as incandescent in that respect.
CFLs are Less expensive and have a lower electricity expenditure.
They are easily available and customizable as no special fixtures are required. They can also be placed extremely close to plants
Florescent works well for germination of any seeds. It also works well with leafy nonflowering crops such as lettuce, leafy greens, most herbs, even strawberries with a diminished yield. They do not meet the optimal requirements of flowering and fruiting vegetables.
They can also work well as supplemental lighting used in conjunction with HID, HPS or even LED systems.
Standard Florescents, T12 and T8 are not powerful enough to light an area more than 10 inches below the light source.
T12 lamps typically emit about 30 lumens per watt, and T8 slightly more.
T5 florescent lights are the best available , they are great for seed starting and cuttings. Because of their low heat output, they can be relatively close to the plants peak to maximize the light output. T5 linear fluorescents will put out about 90 lumens per watt and run cooler.