While HID lights are the heavy hitters in grow rooms when plants need the most light, both fluorescent and now LED grow room lights have their place, too.
There are two different types of fluorescent lights used in grow rooms: Compact fluorescent bulbs (CFLs) and fluorescent tubes (T12s, T8s and T5s):
Compact fluorescent bulbs (CFLs)
CFLs are perfect for small grow rooms with limited space, and are best used for delicate seedlings, cuttings, and small plants that are just getting started.
- Are inexpensive
- Don’t produce much heat
- Don’t use much electricity
- Are easy to find
- Don’t require ballasts to run
If you plan to tend just one plant that won’t grow more than a foot in height, you can conceivably use CFLs for the entire growth cycle. In most cases, however, you’ll only want to start seedlings and cuttings with CFLs. Such delicate plants do well under this soft, cool light.
Use more low wattage bulbs rather than fewer high wattage bulbs, to soften light and disperse heat more effectively.
CFLs are not:
- Suitable for large grow rooms
- Useful for plants that are 12 inches or more in height except when used for light supplementation with other light sources
- Suitable for flowering stages
Fluorescent tubes can cover the different spectrums found in sunlight, just as high pressure sodium and metal halide bulbs can when they’re used as a team. However, they are best used for seedlings, clonings, and small plants. T12s are being phased out in favor of T8 and especially T5 tubes; the number refers to the diameter of the tube:
T12: diameter 12/8″ (1.25″)
T8: diameter 8/8″ (1″)
T5: diameter 5/8″
T5s are more compact than T8s or T12s, so growers can fit more T5 tubes in the same space and thus benefit from more intense light.
- T5s especially produce the best gentle light for small plants and seedlings
- Tubes cost little to run
- T5 ballasts don’t emit heat, noise, or vibration
- Not suitable for plants over 12 inches high, or 24 inches high for T5s
- Poor light source for later vegetative stages of growth or flowering
And finally, the “newest kids on the block,” LED grow room lights.
- Have built in fans to disperse heat
- Plug directly into the wall, no ballasts needed
- Use much less energy as compared to HID lights
- Don’t generate much heat, so there’s no need to exhaust or control heat, in most cases
- May be capable of fostering effective growth even during the flowering stages
- Are still very expensive
- Are not as tried and true as the HID lights for good harvests
- Can be hit or miss in terms of quality
While LEDs are an exciting new development, the quality and strength of the bulbs can still be hit or miss; the LED industry is still in its rapid growth phase and has not been “shaken-out” yet. Because of that and because LEDs are still very expensive, HIDs remain the industry standard for now. However, as technology improves and standardizes, and as prices come down, look for LEDs to take their place in your grow room lighting choices.