How to Select the Right Grow Light for Indoor Cannabis 

Picking the right grow light for your cannabis plants can feel like navigating a complex maze, sometimes more daunting than choosing which strain to cultivate. Unlike selecting from a vast array of options, the challenge lies in weighing numerous critical factors that directly impact your plants' growth and yield.

But fear not! We're here to simplify the process for you. In this article, we'll guide you through the essential factors to consider and introduce you to popular types of grow lights. By the time you finish reading, you'll have the knowledge and confidence to choose the perfect grow light that suits your specific cannabis cultivation needs. So, let's dive in!

Factors to Consider When Choosing Grow Lights to Grow Cannabis Indoors

To choose the best grow light for your cannabis plant, you need to consider some factors related to your cannabis operation, ranging from your budget to your grow room’s area. Here are some of the factors you can consider. 

• How Much Light Do You Need?

So, how much light does your cannabis plant need? This includes not only light intensity but also the spectrum of light. 

For example, the best PPFD for the vegetative stage is between 310 to 620 μmol in 18 hours and, for flowering, it is 460 to 920 μmol in 12 hours. So, you need to pick grow lights that fulfill this requirement.

Some grow lights may not list the PPFD output; instead, they’ll have the output in lux. In that case, you can use an online lux to PPFD converter to get a gist of it. 

Similarly, cannabis requires blue-dominant light during the seedling and veggie stages and red to far-red light during bloom. Here, you need to figure out if you want to give your plant full spectrum light (think, one-size-fits-all) or exclusive spectrum lights. We will discuss the spectrum and the lighting cycle in detail in the next section. 

• How Much Space Do You Have?

When selecting your grow lights, the size of your grow room or tent becomes a critical consideration, especially in compact spaces where managing heat and light distribution is crucial. You want your grow lights to provide sufficient illumination without overheating your grow area.

If you have ample space, you can opt for larger light fixtures that may generate more heat and require adequate cooling and ventilation systems. High-intensity discharge (HID) lights like Metal Halide (MH) or High-Pressure Sodium (HPS) are effective but can raise temperatures significantly, necessitating robust ventilation to maintain optimal growing conditions.

In contrast, if space is limited, LED lights and Compact Fluorescent Lights (CFLs) are more suitable options. LEDs are known for their energy efficiency and minimal heat output, making them ideal for small grow spaces where heat management is challenging. CFLs are also compact and emit less heat, allowing them to be placed closer to plants without risking heat stress.

Beyond light fixtures, think about the overall spatial layout of your grow room or tent. It's essential to leave ample room for maneuverability to tend to your plants comfortably. This extra space ensures you can access all areas of your grow space for pruning, watering, and inspecting plants without obstacles.

By carefully assessing and optimizing your grow space dimensions and lighting choices, you can create an environment where your cannabis plants thrive. Whether you prioritize efficient use of space, effective heat management, or ease of access for maintenance, tailoring your setup to these considerations will contribute to successful indoor cultivation.

• How’s the Airflow?

Is your grow room hot or cold? This is also something you need to consider when choosing the right grow lights for your cannabis plant. For example, if your grow room is generally cooler than what is ideal for your plant, you can opt for lights that run hot. 

Here, you can choose HIDs or MH lights, which have a reputation for heating a lot and raising the ambient temperature in your grow room. In cooler rooms, this won’t be much of an issue because you won’t have to control the temperatures much. 

However, if your grow room is hot and you add HID or MH lights, you’ll need extra equipment like fans and air conditioners to keep the temperature in check. It’s better if you choose cooler-running grow lights here, like LEDs, which don’t require additional cooling equipment. 

Essentially, you want to check how the grow light will affect the temperature in the grow room. It may be cheaper to buy HID grow lights instead of LEDs, but the cost of additional fans and air-con will be more expensive. 

• How Efficient Do You Want Them to Be?

Grow lights consume the bulk of energy in a cannabis grow room. So, energy efficiency is one of the major factors you must consider when growing cannabis. Traditional HID and MH lights are not as energy efficient as LEDs or CFLs.

So, consider how much you’re willing to spend on energy every month. If electricity is cheap in your area and you don’t mind spending much on the same, choose HID or HPS lights. The decision is simple. 

But if you want to keep your energy consumption to a minimum, there’s hardly a better option than LED lights. Don’t forget, that you may also need cooling equipment with HIDs, which will further increase your energy consumption. So, decide carefully about how much money you’re willing to spend on energy. 

• What’s Your Budget? 

Speaking of money, you should also think about the investment required for grow lights. In most cases, for proper cannabis operations, the costs are generally the same in the long run. 

For instance, LED grow lights are expensive from the get-go. A state-of-the-art LED grow light can cost you over €2,000! However, LEDs can last for over a decade and are super energy efficient. You won’t be spending much on cooling equipment, replacements, or energy. This is not to say that all LEDs are expensive. Most LEDs that are cheap also work fine, but they do get expensive if you need many features. 

On the other hand, HPS and HID grow lights are cheaper on the onset but expensive to run and don’t usually last over a single growing season. You’ll need to replace the bulbs and spend a lot of money on cooling and energy. 

Finally, if you’re just starting and don’t have a big budget, you should stick to CFL lights. These lights are dirt cheap and last relatively long. Sure, they don’t produce the same quality of light as LED or HID lights, but the difference won’t matter if you’re just starting. 

Understanding the Lighting Requirements for Cannabis

Proper lighting is crucial for nurturing productive cannabis plants. It can make all the difference between beautiful buds oozing with resin and airy buds that you’d feel embarrassed to offer your friends. 

In a nutshell, if you can understand the intricacies of the light spectrum, the diverse needs for every stage of growth, and the disparities between artificial and natural light, you can significantly boost your endeavors in indoor cannabis cultivation.

1. The connection between photosynthesis and the light spectrum 

Photosynthesis is essential as the plants conduct the process to support their growth by converting light into usable energy. No prizes for guessing, but the spectrum and wavelengths of light are also important in this process. 

Here's a quick overview of the spectrum and plant requirements according to their stages of growth.  

• Blue Light (400-500 nm): This spectrum is especially useful for plants during the vegetative or growing stage where they focus on growing lots of leaves and strengthening their stems and branches. If your grow light has this spectrum along with the appropriate intensity, you can expect some very bushy plants. 
• Red Light (620-700 nm): The plants need this spectrum during the blooming or flowering phase as red light promotes copious amounts of buds. Naturally, if you're using a grow light with red light and an ideal intensity, you can expect a great deal of buds or increased yields. 
• Far Red Light (700-780 nm): Although not as crucial as red light, this spectrum can impact the plant's flowering cycle and overall structure.

So, a grow light that offers all the types of spectrum mentioned above along with UV and infrared rays ensures optimal photosynthesis and development. Full-spectrum grow lights that cover all wavelengths are especially effective for cannabis farming.

Light Requirements of Cannabis Plants According to the Stages of Growth 

Cannabis plants need different spectrums according to their stages of growth — we just covered that. But, there's a difference in the number of hours of light too, depending on whether they are in the growing or blooming stage. 

You will surely know about this if you've grown some plants already; however, if this is your first time, pay attention so you don't end up with lower yields. 

Seedling Phase

The seedling phase determines how the plants will fare throughout their lifecycle. For example, although a seedling affected by some disease, deficiency, or even light stress can recover (chances of survival are low if the plant is very young), it will somewhat struggle to grow as much as you expect. 

Now, if you're a growing photoperiod strain that relies on the light cycle to bloom, you can nurse the plant until it has fully recovered, although it will take quite a bit of time; however, you’re out of luck if you're growing autoflowers as they don't have a lot of time to recover. 

Thus, you need to be careful during this stage as it's akin to caring for a puppy. The seedlings will be fragile and need proper lighting conditions to support root and stem growth.

Light Duration: Some growers decide to provide 24 hours of light with 0 hours of darkness but this is usually not a good idea unless you have no choice. It's best to stick to 18 hours of light and 6 hours of darkness as this will allow the plants to catch their breath, recoup, and get ready to face another day. Conversely, although some growers only provide 12 hours of light and 12 hours of darkness from the seedling stage, it's again not going to work as much as an 18/6 cycle. 18 hours of light is ideal for the seedlings to conduct photosynthesis and grow into big plants. 

Light Intensity: The seedlings are delicate so they don't need high-intensity lights. You can begin with a lower intensity and increase it gradually to prevent any stress or burning. 

Some lights come with various options to adjust the intensity, but you can do this by tweaking the distance as the plants grow. This means that if the lights are positioned about 2-4 inches above the seedlings, you can increase the distance as the plants grow. Also, this distance will depend on the type of light you're using as it varies from one light to another. While seedlings won't have a lot of problems with fluorescent bulbs even when they are close to them, other lights like LEDs and HIDs can burn them. Therefore, follow the manufacturer's guidelines and adjust the distance based on how the plants react. 

You should also make sure that the distance is ideal to prevent the seedlings from stretching too much. Using a fan blowing air gently can also help your cause as it strengthens the stems and wards off mold and mildew.

Vegetative Stage 

The plants will now start developing a lot of leaves and stems. Naturally, they need more high-intensity light to support their development. 

Light duration: Maintain a lighting schedule of 18 hours of light followed by 6 hours of darkness each day. The plants will think that it's the long days of summer and grow more. As mentioned above, you can go with a 24/0 cycle but it's not recommended. However, you cannot use the 12/12 cycle for photoperiod strains just yet or the plants will start flowering unless you’ve been providing 12/12 hours right from the seedling stage. 

Light intensity: As plants grow larger, they will require moderate to high-intensity light to support their increased demands. Use a full-spectrum light to help the plants grow strong. 

You will have to adjust the distance as well. Make sure the plants don't grow too close to the lights or you'll have to face light burn. The light should be evenly distributed across the canopy with no hotspots for best results. 

Flowering Stage 

During the flowering stage, cannabis plants start producing buds. Light is very important to boost the production of terpenes, trichomes, and cannabinoids. In other words, it's essential for the plants to smell and taste good and also produce intended effects. 

Light duration: This is when you can switch the plants to a 12/12 cycle where they get 12 hours of light and 12 hours of darkness every day. For autoflowers, you can continue with the 18/6 cycle as they don't get affected by the light cycle. 

Light Intensity: High intensity is essential for flowering plants to produce lots of buds. Make sure your grow lights are capable of producing what the plants want. Again, use a full-spectrum light for best results. 

Depending on the type of light you're using, you will have to tweak the distance between the lights and plants, or the buds can get bleached and lose their aroma. 

Also, stick to a strict 12/12 cycle every day with no exceptions. The grow tent or room should be completely dark during the dark cycle or the plants will revert to the vegging stage. Or, they can be too stressed and produce seeds. 

What are Your Grow Light Options? 

Grow lights have come a long way in the last couple of decades, due to which you have many options to choose from. Let’s take a look at what your options are and their pros and cons. 

1. CFL Lights

The most basic option is CFL lights, which are so common that you can even buy them at your local grocery store. Plus, they cost less and can last up to a year, making them an incredible option for newbies. 

CFL bulbs come in different color temperatures, playing a crucial role in various stages of your plant’s growth. For example, during the veggie stage, it’s recommended you use daylight CFL bulbs with a color temp of 6,500K, as they mimic the blue light spectrum that encourages robust leaf and stem growth. 

During the flowering stage, 2,700K bulbs are more beneficial as they produce a warmer light spectrum similar to the red light of autumn, promoting flowering. 

Typically, CFL grow lights can yield around 0.3 grams per watt. While they may not provide the same light output as other types of grow lights like HID or LED, their user-friendliness and affordability make them an excellent starting point for beginners. 

CFL bulbs are also easy to set up, generate less heat, and can be placed closer to plants without the risk of burning them, which simplifies the growing process for novice cultivators.

Pros

• CFLs are budget-friendly and widely available in local stores globally 
• They are easy to set up and don’t require any equipment, making them perfect for beginners 
• With various color spectrums available, you can select the light for each cannabis growth stage 
• CFLs consume less energy, leading to long-term cost savings 
• Their straightforward nature and affordability make them an ideal choice for those wanting to grow cannabis easily 

Cons

• They emit dim light that is only suitable for a few plants 
• They are not ideal if you’re aiming for high yields due to their light intensity compared to other options 
• Sometimes, they die unexpectedly, requiring frequent replacement compared to other grow light types 

2. HIDs

HID grow lights refer to high-pressure sodium and metal halide lights. Here, what distinguishes MH and HPS lights is that the former produces cooler light and the latter warmer. 

This is why many experienced growers recommend using MH lights for the vegetative phase and HPS lights for blooming. But if you’re a beginner and don’t want to invest in two sets of grow lights, you’re better off with HPS lights. 

The 600W High-Intensity Discharge (HID) grow light, particularly the High-Pressure Sodium (HPS) variant, is a popular choice among cannabis growers. You can purchase a complete set, including the bulb, reflector, and ballast, for around €150.

Pros

• HID lights are budget-friendly compared to high-end LED lights making them a cost-effective option for a range of growers
• Installing and operating HID lights is straightforward, even for beginners with limited technical expertise
• The intense light emitted by HID lights can result in higher yields and top-quality buds
• These lights offer uniform output, ensuring plants receive consistent lighting throughout their growth cycle
• With options tailored for different plant growth stages, HID lights allow for customized lighting configurations

Cons

• HID lights can potentially burn your plants or cause light stress due to their intense light output. However, if you’re careful and adjust the distance between the grow lights and the plants, this shouldn’t be a problem. Just follow the manufacturer’s advice and you should be good. 
• You need to buy a ballast and a reflector to use HID lights effectively
• HID lights tend to degrade with time and require frequent replacement to maintain optimal performance
• These lights generate a lot of heat and require additional cooling to prevent overheating
• HID lights are not the most energy-efficient option compared to other types of grow lights

3. LED Lights 

LED grow lights have emerged as a top choice in the cannabis lighting sector, offering an effective solution for cannabis cultivators. These lights provide spectrums suitable for all stages of plant growth, and top-notch fixtures allow for customizing the spectrum to meet the plant's specific requirements. 

Modern LED technologies, like quantum boards or chips on board (COB), can outperform HID lights in terms of both intensity and penetration. Moreover, LEDs boast a lifespan of up to 100,000 hours, making them a wise long-term investment.

To fully leverage the benefits of LED technology, it is crucial to invest in high-quality lights. As mentioned earlier, although they may come with a higher price tag initially, the energy savings over time and the improved crop yields they facilitate make them a valuable investment. 

Quality LED lights are available starting from around €120, with premium models reaching prices up to €2,000. You just need to choose a light with good features that will suit your growing space. Depending on the quality and features of the LED lights chosen, you can anticipate yields ranging from 0.5 to 1.8 grams per watt.

Pros

• LEDs are known for their energy efficiency, leading to significant reductions in electricity costs over time
• They produce minimal heat, which eliminates the need for extensive cooling systems and reduces the risk of heat stress on plants
• LEDs provide a high level of customization, allowing you to tailor the light spectrum for different growth stages and minimize the chances of light-induced damage
• Top-notch LED lights can yield abundant crops with premium bud quality
• Many LED setups are simple to install and operate, making them suitable for growers at all skill levels.

Cons

• Premium LED lights can come with a high price tag, requiring a significant initial investment
• The absence of industry standards in LED lighting means that you must conduct thorough research to find dependable and efficient products
• Lower-cost LED lights may lack reliability and effectiveness, prompting you to invest in higher-quality alternatives
• Depending on the LED fixture used, yields could potentially be lower than those achieved with HID lights; however, top-quality LEDs often deliver superior outcomes

4. CMH Lights

Ceramic Metal Halide (CMH) lights, also known as Light Emitting Ceramic (LEC) lights are a type of HID lighting that utilizes ceramic as arc tubes, enabling the bulb to function even at high temperatures. As a result, the grow light produces a spectrum that resembles natural sunlight. Indoor cannabis growers have increasingly favored CMH lights for their efficiency, high-quality spectrum, and overall performance.

Pros

• CMH lights offer a spectrum containing blue and red wavelengths, covering all stages of cannabis growth. As you can understand, it's balanced and diverse, so it easily supports growth and vibrant flowering and can be used for the plant's entire lifecycle from start to finish 
• The light spectrum emitted by CMH lights contains infrared and UV light as well, which can improve the quality and potency of plants. UV light specifically stimulates resin production, resulting in increased levels of cannabinoids and terpenes
• In comparison to HID lights like MH and HPS, CMH lights are more efficient. They produce more light for every watt of electricity they use, reducing your electricity bills and lowering operational costs
• CMH bulbs generally outlast HID bulbs with a lifespan of about 20,000 hours. This longevity reduces the need to replace the bulbs frequency and save you some money 
• When compared to HID lights, CMH lights emit less heat. This helps in maintaining the appropriate temperatures for proper growth. Also, this can allow you to stop using additional cooling systems that may be burning a hole in your wallet already. However, they still emit more heat than LEDs. Thus, if your room is still hot despite using fans, you may need to use air conditioners 

Cons

• CMH lights have a higher cost compared to HIDs. This also includes purchasing bulbs and the ballast it requires to operate properly. Remember, it needs a very specific type of ballast that's not compatible with other setups, which can add to the cost. 
• CMH lights are not readily available unlike other grow lights, which can make them challenging to find in certain regions. This is one of the reasons why they are more expensive — less competition leads to increased prices. 
• While CMH lights offer a spectrum that closely resembles natural light, the quality and consistency may vary among manufacturers. This is not a usual occurrence, though. But, you must always go for branded companies to ensure the lights perform well and last a long time. 

The Best Lighting Option of all the Four Types of Grow Lights

Exploring grow lights may seem daunting at first glance. However, armed with accurate knowledge and insights, you can turn this challenge into an opportunity for a thriving indoor cannabis garden. 

By considering factors like your growing space dimensions, light intensity needs, environmental conditions, energy efficiency, and budget constraints, you can make a well-informed choice that aligns perfectly with your requirements and aspirations.

Whether you opt for cost-effective beginner CFL lights, the potent HID lights known for boosting yields, or the innovative LED lights renowned for their energy efficiency, each option offers unique advantages tailored to various growing scenarios. 

Advances in growing technology have empowered cultivators with exceptional control over their cultivation environment, leading to healthier plants and larger harvests.

Bear in mind that selecting the right grow light isn't about choosing the most popular option, but about finding the light that best suits your specific circumstances. After reading through this guide, you now have the knowledge and insights to confidently choose the ideal lighting for your cannabis plants, ensuring they thrive.

It’s difficult to point to one type of grow light and say you should use it because a lot depends on your specific setup, the number of plants you choose to grow, and your budget. Therefore, go through all your options carefully because making a decision as you won’t be changing grow lights often. 

Tips on Choosing the Best Grow Light for Cannabis 

To help make it easier to set up and use grow lights for your cannabis plants, we’ve got some more tips and tricks for you. Keep these in mind and you’ll be well on your way to growing fantastic plants. 

• Pay Attention to Placement 

When you've picked out your grow light, it's important to place it correctly to ensure your cannabis plants get the right amount of light. Make sure the lights cover your growing area evenly, avoiding any spots that are too hot or shaded. 

For LED and HID lights, it's crucial to keep them at the proper distance from the plant canopy to avoid burning the plants. Adjust the height of the lights as your plants grow to maintain consistent light intensity and distribution.

For best results, follow the manufacturer’s recommendations. 

• Maintain Your Lights 

LED lights are renowned for their longevity, capable of lasting up to 100,000 hours with minimal maintenance. This durability makes them cost-effective in the long term, requiring only occasional cleaning to remove dust and debris.

In contrast, HID lights have shorter lifespans and need regular bulb replacements. MH bulbs typically last about 10,000 to 12,000 hours, while HPS bulbs can last up to 24,000 hours.

You should also clean your grow lights regularly to maintain optimal light intensity and spectrum. Removing dust and dirt from reflectors, lenses, or diffusers ensures maximum light penetration and even distribution across your plants. 

Monitor your grow lights for any signs of damage to prevent efficiency loss and ensure consistent light quality for healthy plant growth.

• Be Safe With Lights 

Safety is key when using grow lights. Make sure your electrical setup can handle the power needed for your lights to prevent fires. Use timers to control light cycles and avoid overloading circuits. 

When using HID and MH lights, be mindful of the heat they produce and ensure they are kept away from anything flammable. Ventilation and cooling systems are crucial to prevent overheating and maintain a suitable environment for your plants.

• Control the Temperatures 

It's best to run your grow lights at full power for efficiency, especially when your plants are in the important budding/flowering stage. In cold areas, you can use bulbs like Fluorescents (CFLs or T5) HIDs, or small LEDs. 

Remember, bulbs emit heat, which can help raise the temperature in cooler environments. HIDs are known for their effectiveness in generating high yields and quality buds in such spaces. 

For those opting for LEDs, larger ones (over 300W) are recommended as they produce some heat. It's important to ensure your plants don't get too cold, as low temperatures can hinder growth and decrease yields when using LEDs.

• Try to Pick LEDs

Plants thrive in temperatures similar to those preferred by humans or slightly warmer. LEDs don’t emit too much heat or don’t let the growing space get too cold either. Thus, it’s best you go with them if you’re a home gardener. 

For enclosed spaces, LEDs are generally the best choice as they provide more options compared to HIDs and deliver better bud quality and yields per watt in warmer environments.

If you're not dealing with extreme conditions, LEDs are typically the best choice for grow lights when cultivating cannabis plants.

Summary: How to Select the Right Grow Light for Indoor Cannabis 

When picking a grow light, consider factors like your grow space dimensions, light intensity needs, environmental conditions, energy efficiency goals, and budget constraints to make a savvy choice that fits your unique setup.

Whether you opt for the wallet-friendly CFL lights, the robust and yield-boosting HID lights, the state-of-the-art and eco-friendly LED lights, or CMH lights that resemble natural light, each option brings its perks tailored to different growing scenarios. 

Remember, picking the perfect grow light isn't just about going for the most expensive or the cheapest option — it's about finding the one that suits your specific needs like a glove. And you're now equipped to make an educated choice, ensuring your cannabis plants receive the ideal light spectrum to flourish.