Many people are well aware of the fact that typical store-bought fruits and vegetables may not be as healthy and clean as we would like them to be. Pesticides and other chemicals may be used to improve the yield rates of the fruits and vegetables that are farmed on open land. Nonetheless, our choices are limited as most of our fruits and veggies are imported and we will not be able to know what they have gone through.

However, now with the advancement in indoor farming, anyone can set up a simple indoor garden for their own supply of fresh organic fruits and vegetables that are totally chemical-free.

The sun is our natural source of energy and also the most powerful source of energy.

Under normal circumstance, less than 50% of the energy from the sun can be used effectively by plants for photosynthesis. This is the wavelength between 400nm to 700nm in which plants can use to make their food. The rest of the energy may not be effective or required for plant growth.

Sometimes, other factors like clouds and shades make it unpredictable for plants to get the necessary amount of light energy whereas high levels of Infra-red (or heat) may cause the plant to dry up.

Hence, one of the possibility to ensure that your plants are getting sufficient light and consistently is to make use of grow lights.

Using LED light modified to specific wave lengths, our Grow Lights ensure that your indoor plants will continue to receive the optimum amount of light needed for healthy growth.

The following are some of the terminologies with regard to Grow Lights:

Wavelength

In general, wavelength is the measure of electromagnetic radiation in nano-meters(nm). The range of visible light which our eyes can respond to is from around 390nm to 750nm. For Photosynthesis to occur, plants requires light energy between 400nm to 700nm. Although in some cases, wavelengths of below 400nm and above 700nm can be used for other purpose like flowering and helping to enhance some colour pigments etc.

As far as Photosynthesis is concerned, not all light energy is the same. Blue and Red produces the highest absorption rate in the plant while Green light is mostly reflected off the leaves and stem. This is why most of the LED grow lights in the market are a combination of Blue and Red.

However, it should be noted that there are some studies which suggests that some Green light is also necessary for the healthy growth of the plants.

Light Spectrum

White light is a combination of different wavelengths at different intensity. Basically, more blue will make your light whiter (or bluish white) whereas more red will make your white light warmer (or more amber).

So does it mean that white light can be used as your plant lighting?

The simple answer is yes. Since white light is a combination of various wavelengths, your plants will be able to absorb the necessary energy for photosynthesis provided the levels of the required wavelengths are sufficient. There are a couple of reasons why white lights are not generally used as grow lights:

Firstly, cool white spectrum consists of a lot of blue and insufficient red light, whereas warm white consists of more red but also have a high level of green and amber (as mentioned earlier, green and amber has lesser effect on photosynthesis than red and blue).

Secondly, it is found that in order to provide a generic balanced light spectrum for plant growth, the ratio of red to blue should be between 3 : 1 to 4 : 1 depending on the plants that you are growing.

Lastly, in order to get the correct amount of blue or red in the system, you will need to increase the power of the grow lights which means higher operating costs.

The efficacy of white LEDs has been increasing at a phenomenal rate over the past few years. This means that white LEDs is able to give more light energy per watt than a standard blue or red led. This is due in part to higher investment being put into improving the performance of white LEDs as they are being used to replace conventional lightings like halogen or fluorescent lamps.

Blue and red LEDs on the other hand, have not been moving at the same pace and generally more expensive than white or warm white LEDs.

Therefore, by combining cool white and warm white LEDs at a ratio of 1 : 3, we were able to create our Horticulture T8 – EASY Tube series of cost effective grow light. This combination is also less hurtful to the eye than a pure blue/red combination.

We also realised that there are some different requirements from more serious farmers who would require a better spectrum for their plants. Can we do just blue and red? Sure, but this would mean that the cost will go up a lot more and the lights may be too disturbing to look at.

So we decided to make some changes to the led combination and came up with the SOLA Series. Actually, this combination was requested by one of our customers in Japan who used the grow light for plant factory application.

By putting in White, 660nm photosynthetic red and blue LEDs combination, we were able to come out with a spectrum which produces more blue and red while reducing the green and amber to a level which still gives an acceptable output but less hurtful to the eye.

PAR and PPFD

Besides getting the correct light spectrum, we need to know how much energy is the plant getting.

The term PAR, which stands for Photosynthetic Active Radiation, is a measurement of light energy for photosynthesis.

Another important measurement is PPFD, which is the Photosynthetic Photon Flux Density. This is the amount of photons which can be used for photosynthesis reaching the target per second over an area of 1 meter square. PPFD is expressed as µmol/m^2/s.

Depending on the types of plants, the PPFD required can range between 50 to 300 µmol.

Another important point to note is that the proximity of the light source is also very important to the PPFD levels. Meaning that if the light source is further away, the PPFD levels will be lower.

Time is also a factor for the measurement of PPFD. This means that the longer you use the grow lights on your plants, there will be more photons for photosynthesis.

Daily Light Integral (DLI)

This is the measure of photosynthetic light intensity over a whole day and expressed as mol per square meter per day. However, we do need to note that it is not wise to continually switch on the grow lights as it is generally accepted that there will be a saturation point for photosynthesis.

Here are some examples of vegetables and herbs grown indoors with our Grow Lights: