When growing cannabis indoors, you typically place the lights on top of the plant, facing down, to mimic the natural sunlight. For most growers, such a lighting setup is completely fine and adequate, but some growers may want to go a step further to maximize the light penetration within the canopy.
Thanks to optimized light penetration, you can boost your plant’s yield and health significantly. This is where under-canopy and side lighting come into play. These supplemental lighting techniques help push your plant to its optimal potential by ensuring your plant gets as much light as it can with minimal dark spots.
Remember, such techniques are not for everyone, especially if you have budget constraints. A hanging grow light setup is more than enough if you’re expecting healthy, happy plants with decent yields.
Many other techniques can come in handy to boost light penetration for cannabis plants, especially some training methods like the screen of green (ScrOG), pruning, bending, and topping.
As a result, side lighting and under-canopy should only be reserved when you’ve tried everything else and still feel like you can extract a bit more from your cannabis plant.
So how do these techniques work, anyway? Your cannabis plant has apical dominance, where the main cola grows the tallest — this is what gives your plant its typical Christmas tree shape.
When the lights are placed directly on top of the plant, the unidirectional light throw boosts this apical dominance, causing the lower branches to grow smaller buds, unless you intervene with training methods.
But you can overcome this problem by placing lights under a canopy and side lighting around your cannabis plant. This boosts the light exposure to the lower buds, allowing them to grow significantly bigger and boosting the yields.
Learn everything you need to know about under-canopy and side lighting for your cannabis plants in this article, including the basics, the pros and cons, and some tips on implementing these techniques properly in your cannabis grow room.
What is Under-Canopy Lighting for Cannabis?
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As the name suggests, under-canopy lighting refers to any kind of supplemental grow lights you place under the canopy; such a lighting system throws light from the bottom to the top, illuminating the lower branches of the plant. This also makes sure no big fan leaves are blocking light from other leaves under it.
You have many options when it comes to under-canopy lights when growing cannabis plants. But for most growers, the best thing you can use is strip lights. These strips must be placed on the floor with the diodes facing upwards.
The benefit of using such light strips is that they are generally LED lights, relatively affordable to purchase, reliable, and adequate for under-lighting. Under-canopy lighting systems need not be as powerful as the hanging grow lights.
Side lighting, which will be discussed later in the article, and under-canopy lighting serve different purposes. The latter is ideal for growers who want to maximize light distribution within the canopy but don’t have as much space to set up side lighting.
Benefits of Under-Canopy Lighting for Cannabis Plants
There are many reasons why you’d want to use under-canopy lighting, but for most growers, only a few reasons will apply.
Perhaps the first reason you should consider using under-canopy lighting is if you’re growing dense cannabis plants. In other words, if you are growing cannabis plants that tend to grow bushy due to strain genetics or have multiple plants cramped in one spot, under-canopy will help.
In such cases, the light produced by the grow lights may not be enough to penetrate the canopy properly and will only throw light on the upper tiers of the plant, leaving the lower tiers in darkness.
Another reason why under-canopy lighting can come in handy for you when growing cannabis plants is if you want to avoid popcorn buds in the lower tiers of the plant. As mentioned earlier, cannabis has apical dominance, and lights under the canopy can help minimize the damage this apical dominance does to the lower tiers of the plant.
Lastly, you can also use a basic under-canopy lighting setup to improve the light efficiency in your grow room. If your plant gets enough light, it will grow healthy and bigger since it can carry out its photosynthesis process more efficiently.
What is Side Lighting for Cannabis?
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On the other hand, side lighting is exactly as it sounds. This type of lighting uses LED or CFL lights placed on the side of the cannabis plant. Most growers like to use tubular bulbs or LED strips hanging around the plant — numerous ones around the plant.
However, if you truly want to mimic the movement of the sun for your indoor cannabis plant, you can even have your side lighting revolve around your cannabis plant. This will ensure your cannabis plant enjoys terrific light exposure throughout the day. Do note that this is usually an overkill for most growers.
Unlike under-canopy lighting, side lighting does not necessarily improve yields or replace training methods. It is better to think of this technique as more of a supplement for your plant’s growth and health instead of a guaranteed yield booster. However, it does improve the quality of the buds to a good extent. Ultimately, it can help you grow large thick buds.
All this lighting method archives is to maximize the amount of light your cannabis plant gets to improve the efficiency of photosynthesis. By ensuring your cannabis plant gets light from all directions, you are helping the plant achieve its optimal health and shape.
You can use side lighting in various configurations, but to use it properly, you need a lot of space. If you are short on space, adding side lighting to your setup isn’t a wise move.
Benefits of Using Side Lighting for Growing Cannabis
Like under-canopy lighting, side lighting only comes in handy in a few instances for growers.
The first way this type of lighting comes into action is if you are growing large strains of cannabis. When you grow really large, tall cannabis plants, the lower canopy is usually too far from the grow lights while you maintain the right distance from the ever-growing upper canopy. So, you can use side lighting to ensure your cannabis plant gets an even spread all around.
On the other hand, side lighting is recommended if you are supplementing carbon dioxide to your cannabis plants. When you use carbon dioxide in your grow room, it boosts your plant’s photosynthesis, but your plant will need more light. And side lighting is the perfect way to supplement more light to your plant so it can use all the extra CO2 you give it.
Lastly, side lighting comes in handy for ensuring your buds grow in a consistent or uniform shape. In most cannabis plants, the buds on the top of the canopy are bigger and those on the bottom are comparatively smaller. But side lighting lets your plant grow bigger buds on the lower branches, too, ensuring more uniformity.
Why Should You Use Under Canopy and Side Lighting for Cannabis?
There are benefits to using these techniques for growing cannabis as they offer specific benefits for a few use cases, such as the following.
There are only two situations where you should consider using under-canopy and/or side lighting while growing cannabis. One, you are growing dense cannabis plants, which can make it difficult for the light to properly reach the lower tiers.
Two, you have taken all the steps to optimize your cannabis plant’s growth but want to go a step further. Then, side lighting and under-canopy lighting can help you optimize your cannabis grow room even more.
In these two instances, using under-canopy and side lighting can be significantly helpful, and it can even produce some excellent results for your cannabis plant, such as the following.
1. Your Plant’s Yield will Improve
If a grower tells you they don’t need more yield, they either own a commercial farm or are lying. Every grower we have ever met has desired bigger yields from their cannabis plants. And these lights can help here, too.
Once you have perfected all the other methods of boosting your plant’s yields, you can move to under canopy and side lighting. These techniques can help prevent popcorn buds, ensure your buds grow big, and improve your plant’s general health.
But for beginner growers, it is wise to learn other yield-boosting methods first before jumping to these techniques. You need to master other methods first and then expect benefits from supplemental lighting.
2. It Improves Light Distribution to Your Cannabis Plant
Another benefit you’ll notice when you use under canopy and/or side lighting is better light distribution for your cannabis plant. By adding these supplemental lights to your cannabis setup, the light will be distributed more evenly to your cannabis plant.
There’s a caveat, though. These lights will only provide any real, noticeable benefit to you if you’re growing dense plants and have exhausted all the other options for light optimization.
3. The Buds Will Become More Uniform
As mentioned earlier, when you use supplemental light, like under the canopy or side lighting, the buds your cannabis plant develops will grow more evenly. Instead of growing bigger buds on the top and smaller buds on the bottom, all the buds will grow in similar sizes.
4. Your Plant Will Grow With More Vigor
All these benefits come together to make your cannabis plant develop much better than otherwise. Of course, a cannabis plant grows perfectly well with a traditional hanging light setup as long as you’ve fine-tuned the spectrum, intensity, and distance of the light.
But adding under-canopy or side lighting to your cannabis plant will only add a cherry to the top. This may make your cannabis plant grow bigger, produce richer colors, or make the canopy more uniform. Your plants may also become more resistant to diseases, pathogens, and pests.
Differences Between Under-Canopy and Side Lighting
While both under-canopy and side lighting aims to improve distribution within the cannabis canopy, they have applications and areas of focus.
Under-Canopy Lighting
Under-canopy lighting is strategically placed beneath the canopy to address certain parts of cannabis plants. Its purpose is to minimize shadows and provide light to areas of the canopy that don't receive illumination from overhead lights. It helps light reach deeper layers of the canopy. Essentially, by delivering light to regions that are typically ignored with traditional grow lights, under-canopy lighting promotes healthier growth, encouraging optimal bud development and reducing popcorn buds.
Side Lighting
Side lighting involves placing lights to illuminate the sides of cannabis plants. It can extend its application to areas where the primary overhead lights may not provide exposure alone. The main purpose of side lighting is to penetrate the foliage reaching areas on the sides of plants. It’s more of a horizontal coverage rather than vertical like regular grow lights. By contributing to canopy penetration, side lighting ensures improved distribution. This helps every part of the plant, including branches that further help them become strong and produce good buds.
While each method has its application and focus, combining under-canopy and side lighting in cultivation setups creates a synergistic effect. Under-canopy lighting takes care of specific regions while side lighting ensures that the sides of plants also receive their share of light. This results in a developed and uniform canopy.
When Should You Not Use Under Canopy or Side Lighting for Cannabis?
Just because under-canopy and side lighting offer so many benefits, you don’t necessarily need to use them. As mentioned multiple times above, such supplemental lighting solutions only work for some growers; for the majority, these are overkill, and here are a few reasons why.
1. It’s an Expensive Technique to Implement
If you’re already growing cannabis indoors, you’ll know that the more grow lights you add, the more you will spend on them. The same formula applies to under-canopy and side lighting.
Yes, under-canopy lighting can be cheap as long as you use basic LED strips, but for anything more advanced or for side lighting, expect to pay a bomb to get the formula right. You’ll need to invest in purpose-built lighting solutions for the best results.
Here, it is always recommended that you perfect your growing techniques and use other, much cheaper methods for optimizing light penetration before moving to under canopy and side lighting. Otherwise, you’re simply draining your money down the hole.
2. Your Energy Bills Will Be High
You’ll have to spend a lot on purpose-built lighting systems, sure, but the expense does not stop there. The more lights you use, the higher your energy bills will get. Plus, more lights add more layers of maintenance to your gardening chores, which can be an entirely different headache to deal with.
3. Your Grow Room Will Heat Up More
One of the most notorious side effects or downsides of using under-canopy or side lighting for your cannabis plant is that they will produce more heat that needs to be managed. Grow lights tend to run hot — even LED grow lights produce some levels of heat — and supplemental light will boost this heat further.
As a result, you really need to manage the heat. And, that adds up to the cost as you’ll have to spend again on air-conditioners or any equipment needed to reduce the heat. If you have such equipment already, then go ahead with supplemental lighting. Otherwise, your cannabis plant can suffer from heat stress, diseases, pest infestations, and more if the heat is not controlled properly.
4. Your Plant Can Suffer From Light Burns
Lastly, you can sometimes give your cannabis plant more light than it really needs. This is a major problem — the more isn’t always merrier, especially when it comes to light for your cannabis plant.
If you use the wrong kind of lights, place them too close to the plant, or aren’t careful enough, your plant will take in too much light, leading to light burn. This is not only stressful for your cannabis plant but it can reduce your plant’s yield while also wasting your hard-earned money.
How to Set Up Under-Canopy and Side Lighting for Cannabis Plants?
You’ve gone through the basics and the pros and cons, and if you think side and under-canopy lighting is suitable for your cannabis grow room, the next step in the process is to learn how to properly set up these systems. Here is a short guide with tips on properly installing under-canopy and side lights for your cannabis plants.
1. Be Careful When Choosing Lights
First things first, you need to know the kind of lights you pick for your cannabis plant. You shouldn’t use fairy lights, random off-the-shelf LED strips, or random CFL bulbs for your under-canopy and side lighting.
As mentioned earlier, it can also be quite confusing to decide between the two. As a basic rule of thumb, stick to under-canopy lighting if you’re short on space and don’t have enough room to place lights all around your cannabis plant.
On the other hand, you should opt for side lighting if you want the best results and have a lot of space around each plant in your cannabis garden.
Ideally, you should use high-quality LED lights as they offer the best results. LED lights of any kind are super efficient, ultra-reliable, and ridiculously long-lasting. Plus, LED lights don’t produce as much heat as HIDs. Yep, it’s an expensive investment but it’s worth it in the long run.
On the other hand, you can even use CFL grow lights or tubes, depending on your preferences, goals, and budget. CFL grow lights are dirt cheap and heat up a bit but it is manageable.
In most cases, you want to avoid HID or HPS grow lights for your cannabis plant for side lighting and under-canopy lighting as they are powerful and emit too much heat.
2. Set Up the Lights the Right Way
Installing under-canopy lighting is pretty straightforward. Simply run your under-canopy light strips under the canopy. Make sure the light strips you use are sturdy, reliable, and water-resistant.
If you are growing a single cannabis plant, you can simply make a small circle with the light strip around the plant’s stem. However, if you are growing multiple plants, run a single trip under your cannabis plants but ensure the light distribution is even.
On the other hand, things get a little complicated when it comes to side lighting. This is where your creative DIY skills will come in handy. You can either hang side lighting around your plant or make dedicated stands to hold the light. It all depends on your preferences, DIY skills, and budget.
3. Adjust the Lights When Required
Don’t make the rookie mistake of using under-canopy or side lighting when your cannabis plant is merely a seedling. That’s asking for trouble. Instead, you need to be meticulous and mindful when using these lighting techniques.
In fact, you shouldn’t use these techniques even when your plants are in their early vegetative stage. During this stage, your plant uses phytohormones that are light-seeking in nature. These hormones guide your cannabis plant to grow toward light.
So, if you were to use under canopy or side lighting during these stages, your cannabis plant may get confused as to where the ground and the sky are. So, the branches may grow out in random directions, leading to a distorted plant structure. That would be counterproductive, wouldn’t it?
Even if this wasn't the case, your cannabis plant won’t be big enough until the mid-vegetative stage where under-canopy and side lighting will make a visible difference. Additionally, lighting will be completely pointless.
Be smart here and start using under-canopy and/or side lighting when your plant is beyond the mid-vegetative stage and make sure your plant needs these solutions. Remember, just because you can, doesn’t mean you should.
Common Challenges and Troubleshooting
You may face a few problems while using these techniques during the growth cycle. As long as you address them immediately, you should be okay. Below are some challenges and effective troubleshooting methods:
1. Managing Hotspots
Hotspots refer to areas where the concentration of light intensity is excessively high. These localized zones can occur due to improper light distribution, the way you position the lights or inadequate reflective surfaces. Hotspots have two consequences: they can cause overheating and negatively impact the health and growth of cannabis plants in those areas. Ultimately, the buds could get burnt and the yields will be marginal at best.
Whether you’re using supplemental lights for under-canopy or side lighting, it can create hotspots if you aren’t careful.
Here are a few things you can do to prevent hot spots:
If you notice that there are several hot spots, you should adjust the height of the lights to ensure even distribution of light across the entire canopy. Raise the lights a bit more, but be careful as inadequate lighting can harm the plants even more. By maintaining an adequate distance between the source of light and the canopy, you decrease the chances of light focusing only on one specific area. Remember the manufacturer’s instructions and make adjustments based on the requirements of the strain.
Reflective materials play a great role in dispersing light and preventing it from focusing on certain spots that lead to hot spots. You can use reflective materials like Foylon film, Panda films, or mylar films inside the growing area to redirect light towards areas that receive less light. Some growers even use electric blankets in a pinch. Reflectors not only help to distribute light evenly, but they also enhance light penetration.
If you still notice hotspots, you will need to adopt other ways. For instance, you can regularly rotate the plants to expose different parts of the plant to varying levels of light intensity. This will prevent one specific area from getting all the light. Essentially, you’re mimicking the conditions the plants experience outdoors. Since the plants receive light in all areas according to the direction of the sun, they grow robust and the stems are pretty strong too. You can do the same indoors. To do so, you can simply turn the containers frequently. However, this may not be possible if you’re training the plants using the ScrOG technique.
2. Managing Light Stress
Light stress occurs when cannabis plants receive too much light. When they get more than they can efficiently use for photosynthesis, it creates an imbalance. It’s like eating much more than you can handle or feeding more nutrients than the plants can take. This imbalance can result in symptoms such as leaf discoloration, curling, and stunted growth. Thus, you must understand these indicators to address issues and maintain the health of your cannabis plants.
The same applies even to light burns where the buds or plants get burned if you position the lights too close to them. If you use powerful lights to provide side lighting, the plants could be stressed.
Here are a few things you can do to manage light stress:
- Increase Light Intensity Gradually
Plants may experience shock and stress if you suddenly provide extremely intense light. If you want to introduce more light, make sure you do it gradually, so they have time to adapt to the changing conditions. The process could take days, depending on how your plants react. The point is to minimize stress on the plants, allowing them to adjust and make use of increased light without any reactions.
- Use the Right Light Spectrum
Cannabis has different stages of growth and they require varying spectrums. If the spectrum is not right, the plants will get stressed. For example, the vegetative period requires more of a bluish spectrum to grow well. On the other hand, the flowering stage will need more red light. So, make sure you use the right spectrum, even if it’s supplemental light.
Rather than using different lights for every stage, you can use lights that allow the spectrum to be adjusted. You can also dim the lights, so use them according to the growth of the plants. Lights that provide the proper spectrum will facilitate photosynthesis and growth, thereby reducing the chances of stress-related problems. Of course, some of these lights can be expensive, but it’s worth your investment as the yields will be higher at the end of the day.
High temperatures can worsen the impact of stress. Heat is the biggest enemy of cannabis plants. Coupled with extreme light intensity, the plants simply cannot grow. Excessive heat speeds up transpiration, which hampers nutrient absorption and increases water loss in plants. Thus, make sure you monitor and regulate the temperature in the grow tent using a hygrometer that measures both the humidity and temperature. Depending on where you live, you can install air conditioners or heaters to maintain the temperature range.
Having enough airflow and ventilation is important to make sure that the heat produced by grow lights can escape and keep the temperature in the growing area balanced. If your grow tent lacks proper ventilation, you can add more fans and ventilation systems to make sure that air circulates well and heat is dispersed effectively.
Good ventilation stops heat from building up in one spot, so you can prevent hot spots. In addition, it lowers the risk of plants getting burned by light, which means that you don’t have to worry too much about light stress and light burn.
Summary: All You Need to Know About Under-Canopy and Side Lighting for Growing Cannabis
Under-canopy and side lighting are exactly what they sound like but not every grower needs these. Generally, you should only resort to these solutions when you’ve exhausted all the other light optimization options and want to enhance your plant’s growth even further.
Under-canopy lighting is what you should use if you only want to eliminate dark spots on the lower end of the canopy. On the other hand, side lighting helps improve light penetration within the canopy. The result would be a much better, more uniform yield from your cannabis plant.
Again, not everyone needs these lighting setups. These techniques are expensive and often not required for most cannabis grow rooms. Additionally, there are some terrific alternatives to side and under-canopy lighting that you should try first.
The best alternative is to use reflective material like panda film, orca film, mylar, or aluminum foil around your cannabis plant to reduce light wastage. You can also use various training methods like LST, bending, pruning, topping, etc. to optimize light distribution within the canopy.
Think hard about whether these techniques will actually make a difference or not and choose accordingly. In any case, if you want to learn how to grow cannabis like a pro with nifty growing techniques, stay tuned to our blog.
