High Pressure Sodium (HPS) Grow lights
– High pressure sodium marijuana grow lights are another good choice however they emit a light that is stronger in the orange / red spectrum, around 2,200k, due to their inherent sodium content. If a gardener were to start a young plant under a HPS bulb, she/he would see impressive vertical growth.
Not only is this a great flowering light, it has two features that make it a more economical choice.
- Their average lifespan is twice that of metal halides, but after 18,000 hours of use or 12 to 18 months, they will start to draw more electricity than their rated watts while gradually producing less light because they will require more energy to maintain the gas inside. HPS bulbs are very efficient.
- They produce up to 140 lumens per watt.
HPS grow lights operate and emit light when an electrical current flows through ionized gas or plasma. They usually require some time to heat up and an electronic system known as a ballast (big heavy thing) is required as a type of resistor. The ballast regulates the electrical current flowing through the circuit. When the ballast cannot supply enough voltage it will begin to shut down as the pressure of the tube reduces. Time to get a new bulb.
HPS grow lights emit a huge amount of heat – just imagine a 1,000 watt heater in your room, it will produce similar heat – and HPS grow light heat is radiant and directed straight onto your plants. You will need to have a large gap between your lights and the plants. Smaller wattage systems (100 W and 250 W) should be hung about 2 – 3 feet from the top of the plants. Medium wattage systems (400 W and 600 W) should be hung around 4 feet from the top of the plants. High wattage systems (1000 W and up) should be placed say 4 – 6 feet from the plant tops. You might need to look into the cooling of the grow room.
The HPS grow light is not very good for the growth phase but better for the flowering phase as they are deficient in the blue spectrum. The best bet is to use a MH grow light for vegetative growth and then a HPS for the flowering stage.
Metal Halide (MH Grow Lights) – A type of HID
MH grow lights – Metal halide marijuana grow lights primarily emit light in the blue spectrum which promotes excellent photosynthesis and therefore green vegetative growth. Blue light also keeps plants more compact, it is the closest thing to real sunlight. If you are going to use just one light this is a good compromise.
The average lifespan is about 10,000 cumulative hours. The bulb will light up beyond this time but due to the gradual decline of light, it is not worth your while to wait for the bulb to finally burn out. If you compare their lumen (brightness) per unit of energy consumed metal halide grow lights produce approximately 65 to 115 lumens (brightness) per watt of energy consumed versus a normal incandescent light bulb which produces between 15 and 35 lumens per watt.
MH grow lights also come in a ‘super’ format; if you can find a ‘super MH’ they will produce around 15% more lumens. More yield!