Indoor Grow lights: HPS vs CFL vs LED

Posted on May 08 , 2021

If you have been a grower, then this question will definitely come to your mind. Which kind of planting lamp is most suitable for planting?

Like water and carbon dioxide, light is a key element of photosynthesis. The correct selection and implementation of the lighting system will greatly promote the growth of plants. Whether you are a professional grower or a simple “home grower”, the priority to keep in mind when choosing lighting is always the same: we want a quality product, and we want to get it at the lowest possible cost!

Keeping these goals in mind, we can begin to list the characteristics we are looking for.

  • Spectrum: Is light suitable for plant growth? How accurately does it imitate the sun?

  • Electricity efficiency: How much light is emitted relative to energy consumption? How many grams of harvest can be used to pay for electricity? What is the ratio between the electricity bill and the light energy that the factory can use (man/j)?

  • Initial cost: How much does it cost to light up my planting area?

  • Duration: How often do I need to replace the bulb?

Keeping these four factors in mind, we compared the planting lights on the market.

HPS and MH discharge lamps


These lamps are undoubtedly the most popular and extensively tested lamps that can be used in various cultivations. These glass bulbs usually have a wattage of 50 to 1000W and contain pressurized gas that is ionized by two electrodes to produce photons.

Over time, the technology has matured and can provide mixed gases that can emit a fairly complete spectrum and have acceptable efficiency when used in conjunction with electronic ballasts.

The latest developments in this technology are CMH (Ceramic Metal Halide) and HPS double-ended bulbs. Both have broad spectrum, and the efficiency is about 1.8umol/j. These lamps produce a considerable proportion of ultraviolet and infrared (approximately 20%): these frequencies help to mimic the solar spectrum, but are almost completely converted into heat. This requires a proper extraction system, and the grower must be careful not to let the growing leaves burn towards light.

On the other hand, the rich green and yellow spectrum allows the light produced by these special lamps to penetrate the leaves, which is difficult to achieve with other systems. Therefore, they are usually installed on the ceiling at a fixed height.

Consumption and cost

HPS has been around for a long time and has worked well, so there are many "loyal" growers who will not replace it with other products.

The initial cost of the HPS system with power supply and reflector is not high (a complete set of 600W kit costs about 150 euros), but the HPS bulb wears out very quickly, so the intensity will decrease after a few months and we will have to replace it light bulb.

We recommend using these systems for growers who occasionally want to spend less money in the short term but still have satisfactory results, especially those who live in cold regions. In this way, the excess heat will become an advantage rather than a defect.

Low consumption fluorescent lamp (CFL)


Low-power CFL fluorescent lamps allow us to replace old incandescent bulbs that generate more heat than light. The operation is similar in concept to HPS technology: the bulb consists of a high-pressure glass tube filled with mercury and rare gas and two electrodes that can generate ultraviolet light energized by an electronic ballast. Then, the light passes through the phosphor covering the glass tube, thereby being converted into white light.

These bulbs also come in various sizes and wattages, and are widely used in professional and home cultivation due to their low calorific value. The quality of the spectrum is acceptable, but the system has many limitations: the emitted light is never too strong to bloom, and the electrical efficiency is lower than the HPS system; for the best brands, it is about 1.3umol/j.

CFL bulbs are still very suitable for providing low-power light sources in the early plant and cloning stages, providing easy-to-use low-heat solutions. Plants can also grow in contact with bulbs without being burnt.

These lamps are cheap and have a long service life (about 10,000 hours of light), we

This system is recommended for growers who need to economically solve plant growth stage problems.

Light Emitting Diode (LED)


LED was conceived by the American inventor Nick Holonyak Jr. in 1962 and has come a long way in becoming a solution that can replace any other system in most applications . So far, we can say that LED dominates the general and sectoral lighting market.

The operation of LEDs is much more complicated than the old technology: a small diode of doped semiconductor material is energized at a constant current. By using the optical properties of different materials, we can obtain different colors.

Although the operation seems more complicated, the technology has been able to establish itself in the market due to its high reliability, superior efficiency and lower cost. LED diodes do not contain toxic gases, so the most important thing is the environment.

LED diodes come in different sizes and wattages, revolutionizing the gardening market by allowing companies to create increasingly effective lighting solutions with increasingly sophisticated light spectrums.

In recent years, some horticultural LED light manufacturers have mistaken growers for victims of improper marketing. They peddled any color other than red or blue as useless and unusable colors for plants. They put forward skeptical graphics, indicating that the green light was completely reflected by the leaves, and they said that they provided you with the most effective product, but they are all fakes, and the product may be rubbish.

The marijuana plantation illuminated by the LED light strip all puts the LED planting light in a bad state. Growers find that they have a characteristic purple light. Although this purple light has fewer heat problems when planting plants, it also causes "stretching" problems, poor harvests and insufficient flower development.

This is not only due to the poor quality of the diode itself, but also due to the lack of all other frequencies in the spectrum. In fact, plants need light with the widest possible spectrum (such as the solar spectrum). Today, the industry is dominated by white LEDs.

Excluding scams from producers who sell invalid products and misleading dishonest producers, today we have lights COB LED from "nearly double the efficiency of traditional high pressure sodium lamps and CFL bulbs (up to 2.6umol/J), especially from Full spectrum.

The efficiency of the light source and the lack of infrared rays make most LED lamps almost no heat dissipation, which is conducive to controlling the temperature of the growth chamber and reducing the cost of air extraction. All of this will ensure that you get a good harvest with less electricity.

The cost is definitely high, but the duration and efficiency of the system will give you a more or less short time to recover your investment.

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