High pressure sodium grow lights are gas discharged lamps that produce light through the excited state of sodium. They have been the preferred lights for hydroponics and indoor gardens because of their high light output which is appropriate for growing plants. These lights emit wavelengths of yellow and red which are the ideal light wavelength requirements for photosynthesis. Some of these light systems combine metal halide bulbs that produce blue light and the sodium lamps to provide flexibility in growing and flowering plants.
As compared to mercury bulbs, sodium lights cause less light pollution. They are also energy efficient and can be used longer than most other setup due to its cycling capability. They shut down when they are almost burned out and cycles back when the temperature is safe for starting up again. When several cycles are observed, this means the lamp is to be replaced soon. With the high intensity, they tend to produce more heat and in most cases, they are fitted with air coolers in special enclosures. The red wavelength could also attract insects that can be detrimental to the plants health.
In areas where sunlight is abundant, the sodium light can be used as a supplement since blue wavelength can be acquired by plants naturally. However, in areas where there are times of the year where sunlight is scarce, they become a necessity. They can be used together with other lamps in a convertible or switchable setup to provide the required light for proper plant growth.
