HPS Grow Light
One of the most important things to think about when growing your plants indoors is appropriate light. A proper grow light is one of the main factors which can guarantee you the biggest harvest in the smallest amount of time. Light is one of the energy sources the plants need in order to grow and give you the most impressive products. In fact, it directly depends on it: for example if you reduce the light by half you get a two times smaller harvest. So if you get poor results when growing your plants indoors than light should be the first factor to question.
There is a handful of different lights used for growing plants. Some of them are used for specific phase of plants life (like vegetation or flowering) while others can be used for both phases. The spectrum color that a lamp produces is important, because plants grow best under different colors depending on their stage of maturity. See the spectrum chart below. HPS grow light is best suited for flowering phase (when the plant is blooming or bearing fruit) because it emits red/orange spectrum light. But a lot of growers use it for the vegetation period as well with a combination of blue spectrum fluorescent lights or withouth them. Blue spectrum lights are better for fruiting or vegetative phase and red spectrum lights are better for flowering phase. In fact, nowadays there are modern blue spectrum enchanced High Pressure Sodium grow lamps (like SON Agro lights). This means that they can be used in all phases of a plants growth. You can expect a bigger harvest with these lamps compared to the regular HPS lamps.
Kelvin Temperature chart
HPS grow lights can simulate the natures lightning (which is the sunlight) very well. Thats why they’re often called HPS/SON lights. Most of the time a proper indoor grow light system is even better when the natural lighting. That is because you allways have the best conditions – there are no cloudy days which is inevitable when the plant is growing outdoors.
HPS system produces more light output per watt of energy consumed than most of other lamps. See the table below. HPS grow light bulbs are relatively small units that produce a great amount of light. That is another reason why people choose HPS grow light for their indoor gardens.
| Lamp Type | Watts | Lumens/bulb | Total efficiency |
|---|---|---|---|
| Fluorescent Bulb | 40 | 3000 | 30k lumens |
| Mercury Vapor | 175 | 8000 | 20k lumens |
| Metal Halide | 400 | 36000 | 36k lumens |
| High Pressure Sodium | 400 | 45000 | 45k lumens |
HPS lights are gas discharge lights. They emit light when electrical current flows through an ionized gas or plasma. HPS lamps produce light when sodium becomes excited. HPS lights can’t run without pre-heating and voltage control. A remote elctronic system known as ballast is needed to start the lamp. A ballast is mechanism that acts as a type of resistor. Its purpose is to regulate the amount of electrical current flowing through a circuit. If we switched an HPS lamp without a ballast than the bulb would explode because of uncontrolled voltage. The ballast ensures that only the required amount of current flows through the arc.
A lifetime of an HPS grow light is from twelve to eighteen months. While these lamps continue to light for a longer period than 18 months, their efficency drops up to 30 percent or even more. That is because more energy is needed to maintain high pressure of the gas and less energy is transformed into light. When the ballast cannot supply the required amount of voltage it starts shutting down the arc – the temperature drops down and the pressure of the gas inside the tube reduces. When the temperature is safe to operate the ballast turns the light on again. However, when you see this happening, it’s really time to think about replacing the bulb.
One of the downsides of HPS light is that it generates a great amount of heat. So you may need to use some kind of cooling system like fans to cool the lamps and the environment they’re in. If the environment is too hot near the top of the plants, you need to lift the lamps higher. You will kill the plant if it’s overheated. On the other hand, a good cooling system can reduce the distance from plant to lamp. And if this distance is shorter, the plant gets more light. And i’ve already wrote about how it affects the final result.
Another factor you have to consider before starting to use HPS lights is a reflactor. A reflector increases light intensity to the direction where the plants are (this way you get more efficiency) and eliminates hot spots. You should mount HPS lamp horizontally. This will boost by 30% the amount of light that actually reaches the plants.
HPS lamps are available in a wide variety of sizes and wattages. Common wattages range from 70 to 1000 watts and the size of a blub depends on the wattage: the bigger the wattage – the bigger the bulb. If you want better results from your yields, you should consider a bigger wattage lamp. The bigger the wattage, the more light is emmited. And light is very important. I will try to write more about this in another post.
Choosing a grow-light carefully is one of the most important things when starting an indoor garden. A modern HPS grow light setup with a blue spectrum added is a perfect choice.