Plant light - lighting technology

Plant light is crucial for the growth of plants in the greenhouse or grow box. Optimal light for plants promotes growth and harvest. Choose the right lighting to ensure healthy plant growth.

Experienced growers now swear by the use of LED plant lights. The reasons for this are compelling, especially the unprecedented efficiency of light-emitting diodes compared to other technologies. There is currently no technology available that converts electrical energy into light more efficiently.

To make things clearer, here is a direct comparison: Conventional light bulbs only have a light output of 2%. This means that only 2% of the energy supplied is used in the form of light. More advanced sodium vapor lamps perform better here and can convert at least 30% of the energy used into light. Plant lighting LEDs with the latest technology do not have an impressive light output of 85%. The cost-benefit ratio is currently unbeatable. There is simply no more efficient lighting option for plant growth than LEDs.

High-performance LEDs have now been developed that have a light temperature of 4000° K, which is almost equivalent to sunlight. The efficiency is around 180 lumens per watt. The emitted light spectrum ranges from ultraviolet through all colors to the infrared range. Plants react positively to this sun-like light, which leads to a more than double increase in yield .
At the same time, electricity costs can be reduced by up to 60% .

The user-friendliness of LED lighting is particularly worth mentioning. The lights we offer are "plug and play". This means: you unpack them, plug them in and switch them on - and everything is done.

Compared to the sometimes more complicated sodium vapor lamps, this is undoubtedly a big step forward. You don't have to assemble anything, you don't have to do any electrical installations, and you don't need any additional equipment such as ballasts or reflectors.

What plant light LEDs are and how they work

LEDs (Light Emitting Diodes) are available in a variety of shapes, but their basic design is always the same. The diode contains a semiconductor that emits light when an electric current flows through it. Plastic or glass lenses are usually placed over this semiconductor, and occasionally reflectors are used for the LED chips.

The most striking features of these small LEDs compared to older lighting devices are undoubtedly their light spectrum and beam angle. Depending on the semiconductor used, the LED produces different colors. This means that the light spectrum of a single chip is quite limited compared to, for example, a sodium vapor lamp. Nevertheless, the targeted combination of different LEDs enables the production of a broad or even specific color spectrum that meets the requirements of your plants. This means that plant lighting LEDs can either be used universally or they meet the exact needs of your plants.
The first question that comes to mind is:

Which lighting for which cultivation area?

What lighting is needed during the growth phase?

To ensure healthy development during the vegetative phase, it is crucial that your plants receive light in the blue color spectrum. The optimal spectrum usually ranges from about 4000 to 8000 Kelvin, with lamps with around 5000 to 7000 Kelvin being considered particularly effective.

Which lighting is suitable for the flowering phase?

To ensure that your indoor plants develop strong flowers with aromatic terpenes, they need light in the red color spectrum. Wavelengths of 2500 to 3500 Kelvin are ideal. Current research results show that the additional use of infrared light (approx. 730 nm) is beneficial for plant growth. For this reason, infrared LEDs are increasingly being integrated into full-spectrum LED lamps.

What are full spectrum LEDs?

Modern LED technology allows the integration of the entire light spectrum that your plants need from germination to flowering. The use of LEDs with different wavelengths ensures a balanced color spectrum. For LED grow lights, the color spectrum is usually given in nanometers (nm) instead of Kelvin. Full-spectrum LEDs usually have a range of around 400 to 780 nm, including the far-red range. Some models such as the Hortimol MHX4 & Hortimol MG8 even offer additional UV-A light in the FSMUV version.

Which lamps are suitable for cultivation?

High-quality LED lamps are now available specifically for growing young plants and cuttings. They generate little heat and avoid hotspots, which protects the sensitive young plants and promotes successful root formation. Solutions such as the Cosmorrow LEDs from Secret Jardin are ideal for this and have practical double power supplies that can supply two LED light strips directly.

Technical specifications for LEDs

The performance

The power of an electrical device is expressed in watts and gives you a rough indication of what you can expect from the light source. It can serve as a first filter criterion, but is less suitable for a detailed assessment of a lighting device or for directly comparing different systems.

Lumen

The luminous flux of a source is given in lumens, but only in the part of the spectrum that is visible to the human eye. This range only partially covers the color spectrum that your plants need for efficient photosynthesis. The lumen measurement also takes into account the different sensitivity of the human eye to different colors. Green light, for example, is perceived more intensely than blue or red light. As you already know, the opposite is true for photosynthesis - blue and red light are much more important for your plants.
The luminous flux specified in lumens is therefore unsuitable for the application of growing LEDs. Just like the power, this can only serve as a rough guide

The PAR value

The PAR value is a better metric and indicates how much energy a light source emits in the color spectrum relevant to photosynthesis. It therefore addresses the problem that exists with lumen measurements. However, it should be noted that energy is not the decisive factor for photosynthesis, as this process is based on quantum mechanical principles. However, the PAR value is a step in the right direction and can help to evaluate LEDs more accurately. In this context, the PPFD value is generally even more precise.

The efficiency

Efficiency describes the ratio of output power (light output) to input power (power consumption). In other words, this figure shows how much light is generated per joule (watt per second) consumed. Light can be viewed both as a wave (radiometric) and as a light particle "photon". If light is viewed as a wave, the light emission of a lamp can be measured in watts. In the case of photonic consideration, one speaks of micromoles. In the area of ​​plant lighting, one does not measure the entire spectral range, but primarily the wavelengths between 400 and 700 nm, the so-called PAR range. However, the consideration of other wavelengths, such as UV and far red, is also becoming increasingly important and has led to an extended observation range of 380 to 780 nm. For a lamp, different values ​​can be specified to consider the efficiency. Module efficiency or system efficiency can be considered.

Module efficiency = efficiency of the light source

The information on the efficiency of sodium vapor lamps refers to the lamp itself. In this context, we speak of module efficiency or efficiency of the lamp. Losses caused by the driver or ballast as well as reflectors, covers or lenses are not taken into account in this information. A conventional sodium vapor lamp has an efficiency of 1.7 µmol/J. This means that with an input power of 600 watts, the lamp produces a light emission of 600 watts x 1.7 µmol/J = 1020 µmol/s.

System efficiency = efficiency of the entire system

As the name suggests, system efficiency refers to the value of the entire lighting system, which includes all components of the luminaire. This can be illustrated using three examples.

Example: Sodium vapor lamp 600W

Efficiency of the lamp: 1.7µmol/J
Ballast efficiency: 94%
In order to supply the sodium vapor lamp with 600W, the ballast consumes more power. In our case, the power consumption of the ballast is 638W and 600W is supplied to the lamp.
The remaining 38W are wasted as heat.

Reflector efficiency: 85%
Since sodium vapor lamps radiate at a 360° angle, they require a reflector.
Even the best reflectors do not work without losses and part of the light is not directed to the plants but is lost.

With the above information we can now calculate the system efficiency of a sodium vapor lamp:

Module efficiency x ballast efficiency / 100 x reflector efficiency/100 = system efficiency

1.7µmol/J x 94/100 x 85/100 = 1.358µmol/J

With a power consumption of 638W, a sodium vapor lamp generates 638W x 1.358µmol/J = 866µmol/s output.

PPFD

This value indicates how many photons in the light spectrum relevant for photosynthesis are emitted by a light source, based on a defined area, usually 1 m². The unit of the PPFD value is µmol/(s*m²) and basically gives you a good idea of ​​the illuminance of your new plant lamp. To visually represent this value, special diagrams are often used that also show the distribution of the light. However, it should be noted that the PPFD value and the corresponding diagrams should never be viewed in isolation. It is crucial to always take the accompanying circumstances into account. For example: At what height was the lamp measured? What was the beam angle? So you can never use the PPFD value alone to compare two systems.