The Different Grow Room Lights and How You Use Them – Part III: High Pressure Sodium Lights


High Intensity Discharge (HID) lights are the most popular of the grow room lights used. There are two kinds: Metal Halide (MH), which we discussed last time, and High Pressure Sodium (HPS), which we will talk about this time. But first, a brief discussion on why these two work so well together.


Metal Halide and High Pressure Sodium Grow Room Lights: The perfect “red and blue” team


MH and HPS bulbs work so well together because each mimics a different stage of sunlight. Plants need both of these stages of sunlight for optimal growth and the best harvests.


Metal Halide


Metal Halide is the best “blue light” source when plants are in their vegetative growth stage. In essence, it emulates bright summer sunlight and provides the perfect intensity that plants need for the best growth. Choose lights that are in the 6500 Kelvin range for best results.


High Pressure Sodium


High-pressure sodium bulbs are high-intensity lights, too, but instead of being “blue” lights that mimic bright summer sunlight, they are “yellow” and “red” in the color spectrum. This light mimics the “red” sunlight of early morning and evening in the spring and fall. This is the type of light you should use when your plants are fruiting and flowering.


How HPS lights work


Sodium lights (or “lamps”) were first produced in Holland in 1932. They create light by producing an electric arc through vaporized sodium metal. Other gases and metals are also used to start the light or control color.


The first sodium light to be developed was the Low Pressure Sodium light. Although it produces a poor quality, very yellowish light, it’s one of the most efficient lights in the world.


The High Pressure Sodium light came on the market in 1964, produced by General Electric.


HPS light considerations


HPS lights are the best “red light” source out there, but they do have two minor drawbacks.


  • They can be pricey


HPS grow lights and systems can cost more than $100; 1000 watt HPS lights can cost $65-$100. (That said, because they are so long lasting and because their electricity use in proportion to yield is so good, the expense is offset by their efficiency.)


  • They contain mercury


HPS bulbs contain a small amount of mercury such that they will have to be properly disposed of instead of simply tossing in the trash.


Advantages of HPS lights


HPS lights are:


  • The best “red light” source for robust flowering and budding


HPS lights in essence “wake up” plants and get them working for the day. While MH lights’ blue spectrum encourages photosynthesis and are best for vegetative growth, HPS’ red spectrum lights stimulate plants to stretch upward and promote bud growth.


  • Very energy-efficient


If you use HPS lights in your flowering stages, you’ll get the most efficient yields in proportion to electricity used of any grow light on the market. They are 10 to 15% more efficient than MH lights.


  • Long-lasting


HPS lights can last as long as two years.


  • Available in easy to use kits


You can buy HPS grow kits with bulb, ballast, reflector, socket, cords and hanging hooks already included. Simply install by hanging on grow light stands or by hanging from the ceiling.


  • Proven results


Like its “partner,” the MH light, the HPS light is a long-lasting industry-standard that gives consistent results. Use these two together as a team to get the best harvests.