use regular incandescent bulbs ("grow bulbs") or halogens to grow
cannabis, this type of light generates huge internode spacing, poor
vegetative growth, skimpy yields, and could set your grow room on fire
due to the dangerous amounts of heat these lights produce. Spend your
money wisely, invest in Fluorescent lighting (good), or H
ischarge lamps (HID-- recommended). HID lighting such as M
alide (MH) or H
odium (HPS) supply the high-intensity light that cannabis needs for good growth and large buds.
Added technical information why halogen lighting is a poor choice for plant cultivation by wannabee2004:
Do halogen bulbs have a good spectral output for plant growth?
No, the spectral plot output of various halogen bulb types is by far the worst.
Are they efficient at generating useful light for plant growth?
No, the best floro/hps/mh lighting each being approx 5X more efficient at plant growth than halogen.
A good way to measure plant growth efficiency of different types of
lighting is PAReff. PAR stands for Photosynthetic Active Radiation: the
wavelength range of light between 400 and 700 nm that can be absorbed
by leafs for plant photosynthesis. PAReff is the PAR/Watt efficiency
ratio over a certain area.
Philips Advantage Fluorescent, 5000K: 1.44 PAReff
Philips High Pressure Sodium deluxe: 1.38 PAReff
Philips Dense-Line Emitter Metal Halide, 4100K: 1.38 PAReff
Philips Spot Halogen Masterline, 2950K: 0.263 PAReff
People usually choose halogen for the "low startup" costs of a
halogen light. The real costs of halogens result from its low
efficiency. 500 Watt halogen lighting produces about 0.08 Watt/s/nm in
the green-yellow spectral region which is about the same as 80 watts of
cfl's. A 500w halogen grow will cost approx $63 for electricity,
whereas a more efficient light source generates the same par value for
around $10 (depending on your local prices).