In this article, we will try to shed some light on this subject: do LED grow lights work? Are they useful for blooming? Are they useful for blooming? Is changing over to them at this time worthwhile? Here are our impressions after a year and a half of growing with LEDs.
Some pioneers already began talking about and introducing this new type of lights – including their functionality regarding our valuable crops – a few years ago. LED grow lights are nothing new to the industry; the only reason their arrival on the Cannabis scene has been delayed until now is that they have never produced a sufficient yield so far. The amount of light obtained with the available watts was always significantly less than that achieved with sodium lights. But LED efficiency at this time is competitive and will no doubt keep increasing.
Do LED grow lights work?
The best way to discover how something works is to try it yourself, which is why I purchased a few LED screens a year and a half ago and began experimenting. For me, the easiest way to ascertain their effectiveness was a comparison with the SOG (sea of green) I have used multiple times in the past. Thus, in the same way as I’ve described before in Soft Secrets Spain – but modifying the 600 watts of an electrical ballast with two LED units of 120 watts each that include a range of flowering – I created my first SOP (sea of purple) – which is the name I have taken the liberty of baptizing this type of cultivation with. But let’s start from the beginning…
When you turn on an LED lamp, the first surprise is the large amount of visible light it gives out, (not to mention how quickly it starts working) as it immediately reaches full power. One advantage is that the entire system is integrated and doesn’t require external ballasts or complex operations. It is a practical system, heats up more than enough and its initial duration without losses is excellent, allowing us to avoid the frequent light bulb changes necessary with incandescent lighting.
The first of my five experiments took place in the summer. This trial already demonstrated an unheard-of, almost utopian possibility for indoor growing; that is, cultivating during the summer season (although with a lower yield) as room temperature near the lamp’s glass rises by just one degree. This can also be considered, at least in part, its Achilles heel.
The fact that this type of lighting doesn’t need reflectors – as its opening angle over 120 degrees is very small – represents yet again both an advantage and an inconvenience. On one hand, this allows an important savings in light and wall reflecting materials; on the other, if we only use a single unit, it needs to be turned up in order to illuminate everything, and this is where problems arise. Turning the LED lights up too high means losing their main advantages: the ability to move them close to the plants, and the fact that they give off a large amount of light without burning their leaves.
The farther these lights are kept from the plants, the more their effectiveness is drastically reduced. The solution, however, is simple: it is much more effective to use several low-wattage units, well-distributed and placed close to the plants, rather than a single huge, high-wattage unit six feet away. This is extremely important advice.
Among the various differences resulting from growing with LED lights, the most noticeable is that the plants usually do not show deficiencies or spots. Their perfect green shade is aided, during the entire flowering period, by moving the light closer without needing to raise the temperature.
They defend themselves very well during the vegetative phase, giving excellent results as regards taking root and maintaining mother plants with very few watts. This is a lifesaver during the summer or for growers who don’t have much space available for mothers. We will speak of this factor in more detail in future issues.
As far as fertilizing goes, standards of care vary slightly. In the case of low temperatures plants need to be watered less frequently; therefore, watering them less, we must make sure to adjust the slightly higher EC parameters in order to be able to provide the same amount of nourishment (although we water them less frequently).
Are they useful for blooming?
The plants begin blooming correctly, with an internodal distance that I wouldn’t hesitate to describe as better than the one achieved with HPS. This shows us that the plant doesn’t go to seed needing more light, nor does it grow more slowly in a different photo period – in fact, things develop just as usual (except your light bill will be more reasonable). As the days go by, the plants form open and resinous flowers whose qualities are already well-developed. The absence of heat seems to better maintain the flowers organoleptic properties. Thus, LEDs can be considered a successful form of lighting during the summer, also for mini- and mother plants.
Problems begin when using them during the winter. After years of being accustomed to using incandescent lighting as heaters, we no longer have those necessary degrees. Low temperatures affect the plants weaker parts: their roots, which tend to atrophy and the pots are impossible to dry for weeks. This fact cannot be ignored, because if it becomes necessary to use extra heating equipment (such as a radiator, air conditioning or anything that consumes a lot of energy) it will have all been in vain, since paying for the electricity required by the air conditioning will cancel out what we otherwise save. For those whose crop isn’t much bigger than a few cubic feet, the ideal solution is to combine both types of lighting. This way you will enjoy a much more efficient synergy that achieves both the temperature of sodium lights and the yield of LEDs.
When I did this during the winter, whenever the plants aligned between the two types of lights were able to choose which way to bend their leaves, it was invariably towards the LEDs. I think this fact is significant enough on its own.
What sort of yield can we hope for?
I was very pleasantly surprised; my first SOP allowed me to exceed the gram/watt ratio, which rarely happens with HPS, especially without CO2. My average was about 440 grams per three square feet, using twenty-five selected clones and 240 watts; afterward I expanded to three units and, with better light distribution, have managed to slightly improve my ratio. Therefore the efficiency of LED grow lights is extremely interesting, provided that cultivation is performed properly.
Should I change over to LEDs?
This subject has already created much controversy on the web and in the sector’s press, with many critics who keep mentioning that they’ve been told that LED grow lights don’t work for the flowering period. This is undeniable, but there is an explanation. When the first models were being publicized, they came with false data, in excess of actual performance. Some people even declared a 90-watt lamp to be superior to a 600-watt lamp (no comment). These high expectations inevitably worked against LEDs; people who bought these expensive models – which also lacked a sufficient spectrum to work correctly – found themselves with very poor results. Thus, the first generation of ground breakers suffered quite a disappointment; but now these lamps are much more complete, combining the spectrum with more efficient LEDs. Also, and most importantly, we now know what to expect and what not to expect. Prices have come down and will continue to do so.
The more creative growers can learn to build their own lights; there are many excellent online tutorials that show how to assemble them with the desired distribution and wattage. Currently, many observations give reliable, non-manipulated results – and growers who obtain good results with sodium lamps actually work more efficiently with LEDs. Those who have already begun to or usually have problems harvesting their crop correctly, on the other hand, find their mistakes magnified. Carelessness makes it easy to stunt a plant’s growth.
Nowadays, several companies offer LED grow lights, especially online. New models and combinations become available every day, so I won’t recommend any particular brands – what’s useful today might be ancient history tomorrow. What I can say, however, is that most lights sold on eBay are very low quality, and are not even useful for cutting; in fact, they are of hardly any use at all. But a widespread and general ignorance ensures their continued popularity on the market, which is a pity because – given the tendency to generalize – this contributes to the poor reputation of LEDs.
We need to try and find out where to obtain tried and tested (and guaranteed) models. And to stop expecting to earn without investing.
LED grow lights: pros and cons
Summarizing this introduction to LED grow lights, we can definitely state that they work – not as efficiently as they were advertized when they first came on the market, but they are definitely between 30% and 60% more effective than incandescent lighting. They are still fairly expensive, but prices are steadily going down while quality increases. If you have the luxury of waiting, wait a while for a change that will guarantee satisfaction. If you think decreasing wattage in a medium- to large crop by combining with HPS is a good idea, you can reduce consumption by around 30% without losing any grams in product. LEDs are also a luxury for summer growing or those growing in limited spaces. They are already a useful reality for many growers.