There are three primary lamp type choices; Metal Halide, High Pressure Sodium (HPS) , and Fluorescent.
T12 Fluorescent gives off very low heat, lower light output and is primarily used to start seedlings and cuttings. New T5 and T8 high output systems are now available that produce enough lumens to grow various plants to maturity.
Metal Halide is green/blue/violet-oriented in the spectrum depending upon the Kelvin temperature, and is the best light when natural light is not available and specifically during the vegetative growth stages.
3000 Kelvin metal halide is an excellent choice for orchids and during the flowering and fruiting stages.
4000 and 4200 Kelvin lamps are used primarily during the vegetative growth stages.
5000 Kelvin metal halide will provide enhanced vegetative growth.
Full Spectrum 6500 Kelvin approximates sunlight, will provide enhanced vegetative growth, and may be used during all growing stages.
High Pressure Sodium is red/orange-oriented in the spectrum and the best lamp for secondary or supplemental lighting and promotes budding, flowering and fruiting.
Standard HPS operates at 2100 Kelvin, produces a high percentage of red/orange spectrum and promotes budding, flowering and fruiting.
Hortilux, enhanced spectrum HPS, produces 30% more blue violet, higher lumen output than standard HPS, is highly recommended during the flowering and fruiting stages, for all flowering plants, and in greenhouses as supplemental lighting.
HPS conversion bulbs operate on Metal Halide grow lights and promote budding, flowering and fruiting. We recommend Eye HPS conversion lamps because they have a spectral energy similar to Hortilux HPS lamps.
Metal Halide conversion bulbs operate on HPS grow lights and promote vegetative growth. We recommend Eye Metal Halide conversion lamps because of their 4500 kelvin temperature, universal operating position and high lumen output.
Most growers use Metal Halide during the vegetative growth stages and HPS during the flowering and fruiting stages.
If you know the lamp type or types that are best for your growing application, visit our Grow Light Choices area for more information on grow light systems. If you still need more details on bulb types, the next section will give you specific information on the different Kelvin temperatures and specific growing applications for Metal Halide and HPS bulbs.
