LED Grow Lights - The Future of Indoors Cannabis Cultivation

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LED Lights

When it comes to lights in the grow room, high end HID lights have always been first choice. But long with advances in technology we have seen the rise of a new kid on the block – and he goes by the name of LED.

When it comes to lights in the grow room, high end HID lights have always been first choice. But long with advances in technology we have seen the rise of a new kid on the block – and he goes by the name of LED. (see also LED vs. HPS)

Just a few years ago, LEDs have been laughed off as a viable grow room lighting solution, but the leaps and bounds that technology has been making is beginning to raise a few eyebrows. Very high quality LED grow lights are now available on the market, and their popularity is beginning to pick up as more and more indoor growers show stunning results; but the notion of viable LED grow lights is one that is still young, and there are many open questions.

What are LEDs?

LEDs produce light by passing a current through a semiconductor material as opposed to burning a filament. This causes electrons to move, which in turn produce light - but without the loss of energy in the form of heat, as with conventional bulbs.

A quick history of LEDs

LEDsThe first LED light was invented by a Russian named Oldeg Vladimirovich back in 1927, however, no practical use was found for it. It was not until 1955 that certain semi-conductor alloys were found to have infrared emissions. In 1961, Texas Instruments patented the idea for LEDs as a light source. To begin with LEDs were only made to be red – these were used in TVs to produce the lowlights produced from the corners. Today, LED technology has progressed massively, and still is. LEDs can now produce lights encompassing the entire ultraviolet spectrum, form visible all the way through to infrared.

Why is the adoption of LEDs slow slow?

On paper, the LED lights of today look to be superior to HPS lights in nearly every single way, but it was not always so. Up until very recently, LED lights could not output the same intensity or quality of light as an equivalent HPS system, with the first LEDs coming out on the market being 1 watt or less. This has resulted in them garnering a reputation for being inefficient. Although LED technology has drastically improved since then, it is still treated with a degree of scepticism. However, this bad reputation is slowly lifting, as more growers realise LED’s potential.

LED vs HID in cannabis cultivation

So, let’s look at some of the pros and cons of LED lights compared to their older HID counterpart, ascertaining whether they worth the investment.

Power consumption

LEDs are what is known as “luminous efficient”, meaning they use electricity very efficiently to produce light. In a lab setting LED light was shown to have an efficiency of anywhere from 150+ lumens per watt, with top end CREE lights obtaining 254 lumens per watt. Comparatively, a standard HPS lamp will have an efficiency of 100 lumens per watt. What this means today is that some of the high end LED systems can save a grower 50% on electricity bills compared to the use of an HPS system both good for your wallet, and the planet.


LED lights do not use filaments. This has resulted in much longer bulb life, lasting between 50,000 – 60,000 hours. Comparatively, most HID bulbs only last 2,000 – 3,000 hours.


Cannabis LEDsLED systems produce very little heat – to the point where most are ok to touch. This is once again due to the lack of a burning filament. Nearly 95% of the energy that HID bulbs use is wasted as heat and radiation; because LEDs don’t burn anything, they do not have this problem. As a result LED lights can be placed 30 - 45cm above the cannabis plants, helping prevent stretch. Comparatively, HID lights have to be 60 - 90cm above the plants to prevent them from causing heat stress. Another advantage of this is that because LEDs produce very little heat, there is obviously no need to invest in an extensive cooling system. Particularly in large grows, where often tens of thousands of watts are heating the building, the difference in the utility bill will make a compelling argument.

On the flip side of this, many cannabis growers, especially in the colder regions of the world, rely on their HID lights to produce heat, keeping the grow room at an optimal temperature. Having to power another heat source to compensate for some of the heat lost using an LED may negate the energy saving you were hoping to achieve. Or possibly a combination of LED and HID turns out to combine the best of both worlds in such situations.

Light intensity

A large problem with LED lights of the past is that they were not able to produce a large enough intensity of light to make them viable for most cannabis growers. Traditionally a HID bulb is the only thing that has ever made the grade. However, some growers have found that LED lights with new 5 watt diodes were able to produce enough intensity to match an equivalent HID bulb, and even outpace it. Some LED systems now boast 10 watt diodes, making them a force to be reckoned with.

Colour spectrums

A high end LED system can now cover all of the light spectrums required to grow healthy cannabis plants. The main spectrums that are required during the life cycle of a cannabis plant are blue and red. Most high end systems will have a mixture of blue and red diodes in order to fulfil this – and with some possible to adjust them based on the current stage of the grow. However, there has been exciting developments in LED technology recently, with RGB LEDs being at the front. These are basically white LEDs that have a perfect balance of red blue and yellow spectrums – much in the same way the sun does. This means that a system that can also incorporate RGB LEDs with the normal blue and red diodes will yield much better results.

What puts these above HID lights is that these LEDs are able to produce the maximum peak spectral output of a specific colour, something a HID light cannot obtain. This means that high quality LEDs output a much better quality of light than an equivalent HID - allowing cannabis plants under an LED light set to the right spectrum will be able to perform photosynthesis more ideally than cannabis plants placed under a HID bulb.

Initial Cost

Good, high end LED systems still come with a hefty price tag. As with all LED products, the price is bound to come down as time goes on. Every year prices are going down, as we‘re still standing at the very beginning of the revolution of light that LEDs will bring. Larger production volumes and replacement of conventional bulbs will drive the price down. 
However, due to the power savings and the life span of the bulbs, they can offer long term savings for growers who are in it for the long run and have the money to invest. After all, the savings from the electricity bill and replacement bulbs quickly add up.

Hash Tips and LEDs

Now, if you‘re still not convinced about the efficiency of LEDs, check out the „hash tips“. That‘s the prime example of how LEDs are offering growers advantages through new technology. The ability of LEDs to output a peak colour spectrum leads to the formation of hash tips. Hash tips are trichomes formations on the top of flowering primary buds that are packed so densely and covered in so much crystal that you cannot actually see any vegetation. Hash tips are the result of maximum resin production, the peak of genetic expression. We can‘t wait for them to arrive at the coffee shops.

Only LEDs will create hash tips, as only a specific wave length will induce their formation. These are LED lights with red and blue diodes that can produce at least 40% 660 nanometre red. What is also important is that the light does not produce 680 nanometre red – this is where the precision LEDs shines through. The less precise spectrum control of an HPS light bulb will mean that it is not possible to remove 680nm red, meaning many cannabis cultivators will never get to experience the joy of hash tips.

The natural mechanism behind hash tips goes something like this: Plants sense potential danger from the abundance of 660nm red light, but absence of 680nm red light. It forces the cannabis plant to activate a defence mechanism whereby it creates extra resin in an attempt to filter out potentially harmful rays.

To get optimal results, the LED lights should be placed about 15cm from the plant during the flowering phase. This will not get much area coverage, but will ensure that as much light as possible penetrates through the canopy, stimulating intense resin production, not only on the primary buds, but also everywhere that is touched by the light.

Conclusion - LEDs lead the way

The advantage of LEDs over traditional light system is obvious. If it weren‘t for the price, only few would continue to grow with anything else. 

Guest Writer

Written by: Guest Writer
Occasionally we have guest writers contribute to our blog here at Zamnesia. They come from a wide range of backgrounds and experiences, making their knowledge invaluable.

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