We are getting more and more questions about plant lamps

For this reason we wanted to give you an insight into our lighting concept. We started with DIY store LEDs ourselves.
Clear. They are cheap and certainly serve their purpose. Light.

But when you deal with the subject of plant lighting, you quickly realize that not all light is created equal. We quickly got doubts whether we were doing the right thing …

Read, learn and test! Values such as lumen, lux, kelvin, par and PPFD do not make understanding any easier. So in addition empirical evidence … We bring light into the dark. 🙂


First a few facts

What is this lumen actually?

Lumen is a unit for the so-called luminous flux. You can deduce the brightness of a lamp from this.
The higher the lumen value, the brighter the lamp appears to us.

Example. 1 lumen is a candle 1 meter away … So the amount of light that is emitted and that humans perceive as such.
Clear. A lot helps a lot, but a plant is not human and therefore has different needs.


Is Lux that animal?

Lux is the light intensity per area. So lumens per square meter.
Roughly speaking, you need 20 lux to see
A covered day has 20,000 lux and daylight around 100,000 lux.
Again, a measurement that was developed for the human eye. Of course you can use it to collect some relevant facts about a light source, but the plant usually doesn’t care either.

Kelvin, Come to me

Degree Kelvin is actually a unit of temperature. In this case the color temperature. It is actually used to judge glowing parts or flame colors. A very hot blue flame has a high Kelvin value. Yellowish to red, the “warm white” low Kelvin value. Daylight is 5500 K. It is a relevant point for interior lamps. The lamp shines comfortably warm or just cold like in the office or storage room. A houseplant does not care whether it is illuminated in white, warm white or cold white. The main thing is that it can metabolize all wavelengths of the emitted light.

PAR and PAr is not the same

For example, PAR30 is not known from old light bulbs. It’s about designs and beam angles. But when it comes to real plant light, PAR stands for Photosynthetic Active Radiation. The PAR area defines the light spectrum that can be used for photosynthesis. Wavelengths from 400nm for deep blue light, 5-600nm for green to 700nm for red light. The absorption range in which the plant absorbs all light is of course larger. UV and infrared light are outside the measuring range. Full spectrum lamps that evenly cover the entire area are particularly suitable for healthy plant growth.

what is photon flow (ppf): micromol / sec.

With LED lamps in particular, terms of photon flux and photon flux density (PPFD) are often used. And that’s actually the most important thing with artificial light. Briefly away. The more the better. You need a spectroradiometer for this. Unfortunately, very expensive, so we have to rely on the manufacturer’s information for these values. But it indicates how many “photons”, i.e. light particles, fall at the speed of light per second onto a defined surface. This is the pure light energy that the plant can convert into chlorophyll and should not fall below 30 µmol / s. Recommendations are 50-100 µmol / s for wintering. If you want additional growth, it should be 250 or more µmol / s.

65/5000 But now let's get away from the theory. We are practitioners.

So. As good lighting researchers, you first need a uniform test setup. Then there are measuring devices and of course different lamps. Armed with lux meters and the like, we took action. What does a DIY store LED actually do?

1700 lumens, 500 lux and 4000 K at 18 W. According to the data sheet, a photon flux of 36 µmol / s. Subjective quite bright. But actually rather emergency lighting for the plant. That was the current state and the plants are growing …
Admittedly slowly, but they are growing … We also know that the values are almost obsolete and a damp-proof luminaire for bathrooms will probably not cover the full spectrum range. But well. It’s always better. Nurseries don’t have several 1000 W lamps anyway.

Sodium vapor

We got sodium vapor lamps from a gardener friend. 600 watts. Wow, we thought. But they are bright. 90,000 lumens and 15,000 lux is already an announcement. A photon flux of up to 1150 µmol / s at a distance of 1 meter were touted to us … But it was roaring hot. Tanning bed and sauna in one. This is pure waste of energy and causes sunburn on the leaves. Especially at 600 watts for several hours a day. So it can’t be either.


So keep looking. It has to be LED technology. Sometimes the high acquisition costs put you off, but a 4-5 times longer service life including massive energy savings speak for themselves because they don’t get as warm as incandescent lamps!

So we bought cheaper, medium and high-priced lamps and looked at the differences. Processing, efficiency and ultimately: growth!

Some inexpensive manufacturers only give 800 lumens and 10 watts. We were able to measure an additional 250 LUX. We now know that other facts are more important for well-known producers. There values of 2300 lux with 145 µmol / s at a distance of 1 meter and up to 900 µmol / s at 20 cm were achieved with an output of 50 watts. The highest PPF in the test. A huge improvement over sodium vapor lamps, because the electricity costs were only a fraction. Growth remained good. But the price-performance ratio with appropriate workmanship was never quite right. After all, we have a tropical climate with up to 99% humidity. The protection class of IP54 is splash-proof, but a bit too low for us.



And there we are now in front of our result … Sanlight Flex series … The only lamp that got two points more for a comparable price-performance. For one thing, it is dust and waterproof. So don’t worry about spraying directly, but the biggest thing was the paint! Not the color of the light. Not even the color of the lamp itself. The color of the leaves. Especially with our distinctive variegation, the green leaves have grown with more color than with other lamp manufacturers. The photon density of almost 41 µmol / s at 19 watts is also great. If you extrapolate that to 600W, we even come to 1250 µmol / s, which a sodium vapor lamp cannot achieve.

Whether it is the more white-red color positioning or just coincidence, unfortunately cannot be clearly defined with natural production. But the subjective conclusion is definitely worth mentioning and that’s why we have added Sanlight to our range. We’re not talking about large greenhouse floodlights in the € 1000 range, but rather about what we all need here.

Small, flexible lighting that is favorable for its performance data and that is the Flex series. Whether as 10, 20 or 30 watts with 45 cm, 90 cm or 1.30 m length, it is suitable for most greenhouses and terrariums. We have now replaced almost all of the lamps and you can see the result in our Insta feed.

If you have any questions, please feel free to get in touch and exchange experience reports with us.

Lumen is a unit for the so-called luminous flux. You can deduce the brightness of a lamp from this.
The higher the lumen value, the brighter the lamp appears to us.

Example. 1 lumen is a candle 1 meter away … So the amount of light that is emitted and that humans perceive as such.
Clear. A lot helps a lot, but a plant is not human and therefore has different needs.