Cultivating cannabis is a science and very few people understand that. People who haven’t grown a seed in their lives don’t understand why you become a mad scientist when tinkering with your little plants in a small corner of your home.
After all, a mad scientist has to worry about lots of things to keep his plants happy, especially when you’re growing indoors. You have to play the part of Mother Nature and nurture your plants, just like she does.
And, while talking about Mother Nature, the one thing that comes to mind is grow lights. You’re using artificial lights to mimic the sunlight, so it’s a crucial decision that can either produce massive yields or duds.
Thanks to the advancement of technology, traditional methods of lighting are being replaced by efficient and customizable solutions. Light Emitting Diode (LED) grow lights have emerged as the leading choice for cannabis cultivation. From the vegetative stage's hunger for extended light hours to the flowering phase's demand for a subtle light shift, LED lights serve as the conductor orchestrating each growth phase with precision.
As we have evolved, so have our cultivation practices, and that has brought us to a point where selecting the lighting is no longer an afterthought but a crucial decision that can significantly impact the health, yield, and potency of cannabis plants. In this extensive guide, we will discuss the profound impact of tailored light spectrums to grow healthy plants. We will also discuss the significance of LED technology, its efficiency, and the pivotal role it plays in indoor horticulture. The complexities of LED grow lights provide insights into their advantages, optimal usage, and the science behind their effectiveness.
Light up a joint…let’s talk about lights!
What are LED Lights for Cannabis Plants?
Your cannabis plant, like all plants in the ecosystem, thrives on energy that is harvested via the photosynthetic process, where light is used to convert carbon dioxide into energy. This process is impossible to conduct without light, and it has been proven that lower light levels can lead to subpar yields in cannabis plants.
Additionally, most cannabis varieties are photoperiod plants, where the amount of light it receives dictates its growth stage. This is another reason why high-quality lights are crucial for a healthy plant and good yield.
During the vegetative process, the plant requires longer days, which is emulated by keeping the grow lights on for around 18 hours every day. These long light hours are used by the cannabis plant to grow bigger and put on the mass. In fact, many growers even keep the lights on for 24 hours to make their plants grow as big as possible during the growth stage. However, this is not really recommended as plants also need some time to recoup and perform well. This theory applies to autoflowering cannabis strains as well, and you should give them a few hours to rest, so 18/6 is ideal for any type of cannabis strain.
When your plant is ready to move into the flowering stage, you need to switch the light to a 12/12 cycle, where the lights stay on for 12 hours followed by complete darkness for the next 12 hours. This switch in the light hours signals to the plant that winter is close and it’s time to start growing flowers.
When growing indoors, light plays a crucial role and in the past, indoor cannabis growers used to rely on Metal Halides, High Pressure Sodium, or CFL lights, depending on their budget, preferences, and cultivation goals. However, in the last few years, a type of grow light is taking center stage — LED lights.
LED is short for light emitting diode, and these lights have overtaken conventional lights in almost all industries, from automotive to construction and from photography to camping, and the gardening industry is no different.
The reason behind this popularity is that LED lights are incredibly energy efficient and produce a strong light without dissipating a lot of heat. Plus, LED lights can last years without needing any maintenance to the diode itself. This is why even many indoor growers are moving to LED grow lights.
LED vs HID Grow Lights
The most common type of grow lights used in indoor cannabis gardens before LEDs were HID lights, which included HPS or MH lights. HID lights are still widely used since they are cheaper and reliable, but they are being replaced by LED grow lights across grow rooms.
HIDs may be popular but they are usually used by those that have been using them for a long time. Truth be told, there are many who love using HID lights over LEDs simply because the yields are slightly more; however, HID lights require a ballast, heat up a lot, and consume a lot of energy — problems that LED grow lights do not have to go through. Also, there are many LEDs that produce yields equivalent to HIDs but they are expensive.
LED grow lights also have benefits over CFL and MH lights since they are more efficient, produce better light, and require less maintenance and running costs.
Should You Switch from HID to LED Grow Lights? Logic would dictate, yes, you should. LED grow lights are incredible, but they aren’t cheap, as mentioned earlier. Yes, you’ll still find cheap LED lights, but they are generally of low quality and don’t produce the right amount of light. So, it’s better to not cheap out on LED grow lights.
If you are okay with the initial purchasing cost of LED lights, you should by all means switch to them. They will save you thousands of dollars in the future in terms of energy bills and bulb replacement. But if you’re a hobby grower who only requires a small light panel, HIDs are good enough for the purpose.
What are the Types of LED Grow Lights?
If you want to use LED grow lights for growing cannabis, you need to know what’s available in the market. LED technology has come a long way, giving rise to a few varieties of LED lights, which offer unique benefits for your cannabis plants. Here are the most common types of LEDs used in grow lights.
1. Standard or Purple LEDs
The standard LED light panels are the oldest and most common ones used for gardening purposes, and they are still widely available everywhere. These grow lights contain small to medium-wattage LEDs in large quantities, often exceeding hundreds, packed in a small fixture.
These LED lights are also known as purple lights since they use red and blue LEDs, which emit a purple light. The best thing about these standard LED lights is that they are cheap — most are manufactured overseas and can be purchased at a low cost.
But there’s a downside, too. These types of LED lights are not usually high quality. They are not so reliable and their light output isn’t so strong, either. This can lead to lower yields in your cannabis plant. They can still work for hobby growers but aren’t suited to larger cannabis operations.
2. COB LED
COB stands for clip-on board, and this type of LED light uses hundreds of small LEDs fixed on a small chip. This construction makes COB LEDs the most efficient type of LED grow lights, and they also produce an intense white light that is closer to the natural sunlight.
Another advantage of COB LED grow lights is that they have an excellent penetration within the canopy, which leads to a more balanced plant of growth, ie., better yields. They produce a light spectrum that is suited for better plant growth.
The downside with COB LED grow lights is that they can be quite expensive to purchase compared to other types of LEDs in the market. These grow lights usually contain multiple COB LEDs along with lenses and reflectors, which significantly raises their MSRP in the market.
For a larger operation, you may also need to purchase multiple single-COB fixtures so you can spread the grow lights evenly for better light distribution over your cannabis plants. This can again be expensive.
3. Spread Style LED Lights
The last type of LED that you should know about is the spread style LED which consists of many small LEDs that are spread out on a larger board. These lights come in two common varieties, spider style and rack style.
Spider-style LEDs don’t use a large panel; instead, they use a spider-like arm design, which gives them an excellent spread. On the other hand, spread-style LED lights have incredibly high energy efficiency levels, so you can get the most out of your wattage. However, both these LED lights can be expensive to buy.
What are the Advantages of LED Grow Lights?
We’ve already mentioned a few advantages of LED grow lights above, but there’s more than what meets the eye with these lights. So, let’s dive into all the major advantages LED grow lights offer to cannabis growers like yourself.
1. Energy Efficiency
Perhaps the biggest advantage of LED grow lights, at least for your wallet in the long run, is how energy-efficient they are. LED lights use a lot less energy to operate and the light produced by them is also quite consistent. This is why wattage-to-intensity conversions don’t work with LED lights since, unlike HIDs or CFLs, the amount of wattage does not dictate the light output.
Yes, high-quality LED lights are expensive to purchase, but in most cases, the initial high cost is always worth it. You will be saving hundreds of dollars in energy bills and the lights will more than make up for it in a few months. And remember, these lights can last for over a decade with minimal maintenance!
2. Cool Operation
One of the biggest downsides of HID lights is that they heat up a lot, requiring you to use fans to keep them cool while having to worry about the growing room temperature. Say goodbye to this woe with LED lights, which run cool and don’t spike the temperature in your grow room.
Yes, LED lights can sometimes produce a bit of heat, but it’s not searing heat that will cause issues. This heat is often dissipated by inbuilt heat shields or fins that grow lights come with, at least the high-quality ones.
3. Closer Placement to Plants
Since LED grow lights don’t heat up a lot, they won’t stress out your cannabis plants, either. So, you can place LED grow lights a lot closer to your cannabis plant to increase the light they receive without any side effects for the plant. Remember, higher intensity leads to better yields!
4. Water Conservation
Another benefit of the cool-running LED grow lights is that they don’t evaporate the moisture within the soil as quickly, so you don’t need to water your plant as frequently. Typically, cannabis plants with HID grow lights need to be watered a lot more, and you will notice the difference once you switch to LED grow lights.
Additionally, you also need fewer nutrients since you won’t be watering the plant as frequently as otherwise. That’s another win-win situation as it prevents nutrient lockout and saves you money on expensive nutrients.
5. Customizability
Lastly, some LED grow lights also come with customization and offer millions of colors and brightness levels that you can customize based on your preferences and the plant’s growth stage. They are just like the smart lights used in your kitchen!
6. Increased Lifespan
In cannabis cultivation where precision and consistency are crucial factors, the lifespan and durability of lighting sources play a significant role in overall operational efficiency. You can attribute the longevity of LED Lights to their semiconductor technology. Unlike lighting sources such as HPS lamps that rely on gases, LEDs operate without these components that degrade over time.
Needless to say, LED grow lights commonly have lifespans that exceed tens of thousands of hours. This extended lifespan ensures a dependable source of light for a longer duration, so you don’t have to replace the lights frequently.
7. Lower Maintenance Costs
Adding to the previous point, a longer lifespan of the bulb translates to lower maintenance costs. You not only enjoy savings due to fewer bulb replacements but also save significant time and effort on maintenance, allowing you to focus more on optimizing growing conditions and promoting plant health.
Do LED Grow Lights Have Any Disadvantages?
Yes, LED grow lights are not perfect and they do have a few disadvantages. While these are generally not dealbreakers, it is good to know about them nonetheless. Here are the common drawbacks of LED grow lights for cannabis plants:
- Low-quality LED lights are cheap but they don’t produce high-quality light in terms of the spectrum of intensity
- It’s hard to know whether a manufacturer uses high-quality LEDs or otherwise and you have to rely on customer reviews
- Since LED grow lights do not heat up, they can be a problem for growers living in colder regions
- They are expensive — no matter how much you sugarcoat it, LEDs will cost you a significant chunk of your gardening budget
- Cheaper LEDs do not produce as much yields as HPS lights
What are the Factors to Consider When Using LED Lights?
If you want to extract the benefits of LED grow lights, you shouldn’t walk into a store and purchase any LED light. There is no industry standard in the LED segment, so every manufacturer tends to play by their rules. Plus, using LED grow lights is a lot different from using other kinds of grow lights.
So here are a few factors you must consider when purchasing and using LED grow lights.
1. Price
You can’t get around this — LED grow lights cost a lot. So, it is a good idea to set the stage by setting a realistic budget and getting grow lights that offer the best bang for your buck. For your operation, good LED lights may either cost $100 or $1,000, depending on what kind of lights you use.
For example, LED grow lights with full spectrum will be more expensive than a basic LED panel without UV lighting. Other factors that come into play are the diode brand, warranty, light intensity, etc.
2. Light Intensity
The next thing you need to factor in while getting LED grow lights is how much light they produce. Do not make the mistake of relying on wattage — unlike HID lights, LEDs don’t convert wattage into light in a consistent manner. Depending on the diodes used, some LED light panels use lower wattage to produce the same amount of light as others.
Instead, what you need to focus on are photosynthetic photon flux (PPF) and photosynthetic photon flux density (PPFD) when picking grow lights. PPF indicates the number of photons that are photosynthetically activated, produced by the light per second. This is measured in μmol/s and is the official measurement of LED grow light production.
On the other hand, PPFD is the number of photons that reach a meter square area per second, which is measured in μmol/m2/s. This measures the amount of light that reaches your cannabis plant instead of measuring the light at the source, and thus, it is the most reliable way to measure the light produced. More on the right PPFD for cannabis plants later.
3. Light Spectrum
The next thing you need to take care of is the spectrum of light produced by the grow lights. Not all LED grow lights produce full spectrum light, and some can even produce one color of light predominantly over the rest.
For most growers, full-spectrum grow lights are the best as they produce blue light, PAR light, red light, far-red light, and UV light — all of which are good for cannabis plants. Full spectrum lights can be used throughout your plant’s life cycle with minor adjustments to the light output.
4. Coverage Area
You also need to consider the coverage area of the grow light — there’s no point purchasing a grow light that throws wide light when all you’re growing is a single plant. Depending on the size of your operation, choose a light with an appropriate throw. For example, hobby growers can get away with a throw of five square meters or even lower!
5. Diode Brand
You also need to consider the diode brand used in the LED grow lights — this dictates how efficient and high-quality the light will be. In general, avoid growing lights with no-name diodes or those sourced from unknown brands. Look for high-quality ones — common diode manufacturers include Samsung, Philips, Cree, Osram, etc.
6. Warranty
Lastly, consider the warranty. LED grow lights are expected to last for a decade but you never know what can go wrong with one, and getting them fixed can be expensive or impossible. So, it is always a good idea to get grow lights with the right certifications and warranties — sometimes, even an extended warranty is worth it.
How to Set Up LED Grow Lights?
So, you’ve finally got yourself LED grow lights? Now it’s time to install them. Here is a short guide on setting up your LED grow lights for cannabis plants.
1. Position
For the seedling stage, you should ideally place your LED grow lights 24 to 36 inches above the plant — the furthest distance to protect the delicate seedling from heat and light burn that can still occur with the coolest-running LED lights. This also prevents the seedling from drying out.
On the other hand, you can place your LED grow lights 12 to 24 inches from the canopy during the vegetative stage. Your plant requires a lot of light during this time, so you can place the lights much closer to the plants.
As the plant moves into the flowering stage, you can move the lights to 18 to 24 inches; the plant’s light demand goes down during this stage and the plant will also experience a flowering stretch, so it’s a good idea to move the LED grow lights up by some inches.
2. Keep PPFD in Mind
The distance is only one side of the story, acting as a good starting point, but if you want to nail down your LED grow light’s distance, you need to focus on PPFD, ie., the amount of light reaching your cannabis plant. Here are the recommended light amounts for a generic cannabis plant:
- 200 to 300 μmol/m2/s for 18 hours during the seedling stage
- 300 to 500 μmol/m2/s for 18 hours during the vegetative stage
- 1000 μmol/m2/s for 12 hours during the flowering stage
Chances are, high-quality grow lights will already come with PPFD readings for the panels, but if they don’t, you can always measure PPFD using a PPFD meter or a lux meter (you’ll have to convert the reading, though).
And remember, this is just a baseline. Your cannabis strain may have completely different light requirements, so always follow the seed bank’s recommendations and manufacturer’s advice on positioning the LED grow lights.
Additional Tips on Using Grow Lights
When cultivating cannabis with artificial lights, your success depends on how well you observe and adapt to the evolving needs of your plants. This is why you’ll often find expert growers very attentive and attuned to their plants' subtle cues and reactions.
Make no mistake — regularly observing how your plants react to the grow lights isn’t a practice, but a skill. It can make all the difference between a fruitful harvest and potential setbacks because plants communicate about their health through cues you’ll pick up over time. For example, by observing how your plant reacts to a particular light with specific spectrums, intensity, and duration, you can create an environment tailored for its growth.
Apart from the right distance, here are a few tips to help you get the best out of your LED grow lights:
- LED grow lights produce an inferior light distribution compared to HPS, but this can be fixed with the help of a light rail that helps improve the coverage of the light
- Healthy cannabis plants will have lush green leaves that are well-hydrated, which indicates that they are getting enough water and nutrients.
- If your lights are good, you’ll notice consistent growth throughout the canopy, which tells you that the light is doing a good job of distributing the light in a uniform manner. The growth will also be steady since stunted growth typically means that the plant is suffering from some sort of deficiency or pH imbalance.
- Keep records documenting growth indicators like height, leaf development, and flowering onset so they serve as references for adjustments and troubleshooting.
- Measure how your plants are performing by comparing them with the advertised values by the manufacturer. This will help you make adjustments accordingly.
- Be ready to adjust the spectrum, intensity, and light duration to cater to your plant’s needs.
- Irrigate your plant in smaller quantities since moisture evaporation will be significantly lower with LED grow lights
- Avoid buying cheap, low-quality LED lights — they are often worse than CFL lights and not worth the money
- Always follow the manufacturer’s recommendations over anything else — they know the grow lights best
- If the leaves closest to LEDs are yellowing or turning brown, you need to pay attention to the light intensity and the distance between the light and the leaves. This is because the leaves could get burnt if they are placed too close to the lights. To solve this problem, prune the dead leaves, adjust the distance, and watch your plants for a while to make sure they are not deprived of light. Place your hand under the grow light, above the canopy — if you feel too warm, the light is too close for the plant, too
Summary: Using LED Grow Lights to Grow Cannabis: Dos, Don’ts, And Tips To Get Fantastic Yields
LEDs have become very popular due to their excellent technology. While you can still use HPS lights due to their ability to produce higher yields, you will do better by saving power and money by investing in an expensive LED.
In short, LEDs offer energy efficiency, customizable spectra, and a cooler operational stance. By considering factors such as spectrum, intensity, and coverage, these lights become the guiding force, empowering you to grow healthier plants and get abundant yields. If you take the time to understand how they work and adjust things according to your plant’s needs, you will not regret your decision to purchase LED lights.
