Pioneering Hydroponics

Since 1976

Guide to High Pressure Sodium Lighting

HPS Lamp

High Pressure Sodium Lighting

High Pressure Sodium (HPS) lighting is an efficient way of getting light to plants. It stimulates plant growth by diffusing the portion of the electromagnetic spectrum ideal for photosynthesis direct to your plants.

Because HPS lighting closely mimics outdoor conditions, such as colour and temperature they prevent plants from growing overly long or spindly.

HPS comes under the general category of High Intensity Discharge or HID lamps.


HPS is one of the most efficient methods of lighting your plants when compared to the alternatives.

It is estimated that at 40% efficiency, it is a more productive lighting source than Metal Halide (35% efficiency) or even LED’s (30% Efficiency).


How do HPS Lamps work?

Basically, the lamps contain a pressurised crystal vessel which is filled with a precise mixture of Xenon, Sodium and Mercury, which when an electrical charge is passed through create the wavelengths of light plants need.

Within the lamp a miniature bolt of lightning, which is incredibly high voltage (Around 4-5000 volts) is passed between 2 electrodes.

At this point the sodium in the lamps produces a reddish colour, whilst the mercury produces the blue light. The combination gives it its distinctive orange glow.
The xenon is inert and acts as a carrier for the electrical flow between the electrodes in the lamp.



Because a standard electrical socket will not have enough power to ignite your lamp, you’ll need to use a ballast to convert the power to a suitable level to power the light.

The ballast will make sure that any inrush of electricity does not damage your lamp, but also regulates the power once it’s in use.


Benefit of HPS

HPS lamps are likely to last longer than their closest counterpart the Metal Halide lamp. It is estimated that HPS will last up to 24,000 hours.

Also, if reducing your carbon emission is high on your agenda, then HPS beats Metal Halide in this regard too.

They emit light in the ideal spectrum for flowering plants, with high amounts of red light available.

Finally, HPS lamps are energy efficient, so there’s little need to worry about how much you’re going to spend on electricity. This is though is relative as a LED’s are even more energy efficient and can cost even less to run.

Lamp Life


Negatives of HPS lamps

HPS grow lights can produce quite a lot of heat, which as you’ll likely know can cause problems which are difficult to solve in a growing environment. Therefore, having adequate ventilation is essential when using HPS lighting.

The heat that HPS lamps produce means that you’ll have to position them further away from your plants than other lower temperature lighting methods.

The heat generated means that it is necessary to place the lights at some distance from the plant tips to avoid them being damaged.


This means the maximum amount of light intensity cannot be felt from the plant.

So, there you have it. A run through of what HPS lighting is and the benefits of using it.
If you think HPS lighting is something you want to use on your next crop, check out Street Light HPS lighting

Street Light HPS products