Best Lights For Growing Cannabis Indoors

When I started my first grow room I was frustrated with how little my plants were growing. It soon became clear that having the right grow lights was fundamental for the process.

After years of learning and researching lights I can finally tell you what are the best grow lights for growing cannabis indoors.

Types Of Marijuana Grow Lights

LIGHT TYPE
DETAILS
MY RATING
MY #1 RATED
best-led-grow-lights-2020

LED Grow Lights

  • LED lights are incredibly cost efficient grow lights, you’ll get back your investment in no time.
  • Pack a punch with high-wattage lights available.
  • Very easy to set up as you need nothing other than a plug socket.
drcannabis-stamp

My #1 Rated

4.5/5
4.5 out of 5
MY #2 RATED
  • HID lights provide an exceptionally high yield per watt of electricity.
  • No guesswork when hanging these lights, you get the ideal distance every time.
  • Combining lights gives you a great color spectrum for cannabis.
drcannabis-stamp

My #2 Rated

4/5

4 out of 5

MY #3 RATED
  • T5 lights give exceptionally high intensity per watt for this style of light.
  • These bulbs average about 20,000 hours of life.
  • Generate very little heat, keeps temperatures in your grow room down.
drcannabis-stamp

My #3 Rated

4/5

4 out of 5

MY #4 RATED
best-fluorescent-grow-lights-cfl-t5

CFL Lights

  • CFL lights are a very affordable option with low buying costs and low running costs.
  • Efficient lighting during the first stages of growth as you can place them right up close.
  • An excellent choice if you have very limited space in your grow room.
drcannabis-stamp

My #4 Rated

3.5/5

3.5 out of 5

Lighting Terms That You Should Know

First let’s see some key terminology that you’ll encounter when researching grow lights. I’ll introduce the concept of color spectrum, light intensity, and how to measure light.

These things are not essential to every grower, but are the core of why and how grow lights work. Knowing this you’ll be able to tell the differences between various types and models and grow your plants more effectively. You’ll be able to learn more about one subject by clicking on the linked sources throughout the text.

What Is A Color Spectrum?

Well, sunlight has all the different colors of the rainbow merged into one. When this happens, the light becomes white in appearance.

So, where does color spectrum come into play?

electromagnetic-spectrumSimply put, it is a visual display of all these different colors within the sunlight. If you looked at a color spectrum, it would resemble a rainbow.

We humans see light in wavelengths from 380 to 680 nm, while plants’ sensitivity to light ranges from 300 to 800 nm.

What we know as ‘blue’ can have a wavelength between 420 and 460. It looks the same to us, but they have different properties.

When you use grow lights, they will use a custom color spectrum, with values in between this ranges, to help plants grow and flower more efficiently.

Best Color Spectrum For Cannabis

Color spectrum for cannabis plantsWhat is the best color spectrum to use when growing cannabis? Or, does this even exist?

There is no ‘one ring to rule them all’ with the color spectrum. All colors are needed, but some a lot more than others.

Cannabis plants respond well to both blue light and yellow/red light. Blue light is at the lower end of the spectrum and we see it as very bright and direct lighting. Yellow/red light is much warmer in our eyes.

Let’s take a step outside into the world of outdoor cannabis growing for a second, and take a look at the spectrum of the sun throughout the year.

Blue Light For Cannabis Vegetative Stage

The blue light will be most prominent during the summer months as the sun is high and very bright in the sky. Your cannabis plants will grow stronger while using grow lights with higher ratio of blue light.

Blue ranges from 400-500 nm, the ideal value would be 460 nm.

Red Light For Flowering Stage And Better Yields

The warmer light is seen later in the year when the sun drops lower in the sky and isn’t as bright. A cannabis plant notices this as a sign to start flowering, therefor grow lights with higher amounts of red are best for flowering stage.

Red ranges from 620 to 780 nm, with the ideal being 660 nm.

Does The Ideal Color Spectrum Make Any Difference?

Having said this all this, using the exact color spectrum won’t determine the success or failure of your crop. Most grow lights you can get today will include enough blues and reds to take you from seedling to harvest without issues.

You can even use warmer grow lights during vegetative stage, if you prefer your plants to grow taller and have more space between the nodes. This comes in handy for some grow training techniques like LST.

Studies Pointing To Red Light For Vegetative

There are recent studies claiming that red light is actually more beneficial for plants, due to blue light being less efficient in driving photosynthesis.

I’m not a light scientist so I can’t argue with them. Still, this is not the common knowledge that you get from highly trusted sources.

Light Intensity: What Is It?

Light intensity refers to the power of light source. In more technical terms, it is the magnitude of light energy per unit of area.

Different grow lights will have different intensities, as it highly depends on the type and the quality of the bulb.

Light intensity it’s at its greatest point at the bulb itself, then weakens as you move further away from it.

So, a plant that’s directly under a grow light will receive far more light intensity than one that’s a few feet away.

Light Intensity For Cannabis Plants

All plants need light to thrive – which is the whole reason you need grow lights in the first place!

But, light intensity can improve or hinder the way your plants grow.

For example, imagine you place all your plants very close to the grow light for maximum intensity. Sounds pretty great, right? Well, not quite.

Prolonged exposure to intense light will burn up the plant. The leaves will shrivel up and die. This is because the plant absorbs too much energy and destroys itself.

With too little light they are unable to produce chlorophyll. Worse yet, they start to grow all long and gangly. You end up with stretchy plants because they’re literally reaching out for more light.

Thus, having the right light intensity is essential to ensure your crop is successful.

The best grow lights will provide you with the perfect amount of light intensity. And will also come with details about the area they cover and plant distance instructions.

How Light Intensity Is Measured

Not so long ago we used to measure Lumens when we wanted to see if we had enough light. Lumens are a great way to measure light for humans, but they do not tell us how well plants will respond to visible light.

To measure our grow lights we’ll be using PAR and PPFD.

Photosynthetic Active Radiation (PAR)

PAR stands for Photosynthetic Active Radiation. In essence, these are the wavelengths of light that your plants use in photosynthesis. Which is is crucial for the correct development of cannabis.

It’s common to measure PAR in watts per square meter (W/m2) to see how much is present throughout your canopy.

However, the chemical reactions of photosynthesis are more dependent on the number of photons than the energy contained in the photons.

Therefore, plant biologists often quantify PAR using the number of photons in the 400-700 nm range received by a surface for a specified amount of time, or PPFD.

Photosynthetic Photon Flux Density (PPFD)

Photosynthetic Photon Flux Density tells you how intense light is.

PPFD measures the amount of PAR that actually arrives at the plant. You’ll see PPFD measured as micromoles per second per square meter: µmol m-2 s-1.

This describes the amount of active photons hitting a surface on a one square meter area in one second.

A 2010 study looked at PPFD in cannabis and found that somewhere between 1500-2000 is the best for growing cannabis indoors. However, this optimal range is not common in commercial grow lights as it can draw a lot of electricity and be very expensive to run long term.

You will most likely use grow lights that are less intense, but will be more than enough to produce a great yield.

  • Seedlings, clones, and mother plants can be successful with 200 to 400 µmol m-2 s-1 PPFD.
  • In vegetative growth 400 to 600 µmol m-2 s-1 PPFD can be enough.
  • Flowering plants will enjoy more intense light with 600 to 900 µmol m-2 s-1.

If you want to find out the true light intensity of a lamp over a designated growing area (i.e. 4’ x 4’), it is important that the average of several PPFD measurements at a defined height are taken.

Lighting companies that only publish the PPFD at the center point of a coverage area grossly overestimate the true light intensity of a fixture.

What To Consider When Buying Grow Lights

It helps to know what to think about when looking at different grow lights. I’ve come up with the most critical points to weigh up when making your purchase. Keep all these things in mind if you want to find the best grow lights for your crop.

Price And Long Term Costs

I can’t pluck a figure from the sky and say yes, that’s how much you should pay for great grow lights. It’s impossible.

While price is important, much depends on your own situation and long-term goals. You will come across LED, HID and CFL lights on the market, and the prices tend to vary based on the type as well.

Don’t forget that lights come with operating costs as well!

Consider how much energy each type of light uses when they are in operation.

Some lights are much cooler, while others put out a lot of heat. Depending on your choice you might need cooling equipment.

Wattage: How Much Light Are You Actually Getting?

Next, you have to think about getting the perfect amount of light for your grow room. I mentioned before that too much light is bad, and so is too little.

What’s the perfect goldilocks amount? How much light is right for you?

There’s actually an equation to figure this out. And it looks like this:

  1. Grow room length x width = Total growing surface,
  2. Total growing surface x desired PPFD level,
  3. The result from the previous equation is divided by the PPFD per watt of light,
  4. This gives you the precise amount of wattage required for your room area.

Hold up, what’s PPFD per watt?

I know this can be a bit confusing, so bear with me. When you buy grow lights, the manufacturer should outline the wattage of the bulbs and the PPF value. You can then work out the ratio of PPFD per watt by taking these two values and doing some simple math.

For example, a 250W bulb with 450 PPF. So, 450/250, equals a ratio of 1.8 PPFD per 1 Watt of light.

There you go, take your result and use it in the instructions above!

I also recommend thinking about how many watts per square meter you need for all your plants.

This can vary depending on the lighting system you use. As an example, LED lights with 280W of power have the ability to cover 1 meter squared, which is around 4 plants.

The larger the room, the more wattage you require for a consistent light intensity across all your plants. You can use the previous equation to figure out how much you need.

Temperature And Cooling System

Light bulbs create a lot of heat. Too much heat is bad for plants as it compromises growth and basically burns them out from the inside.

Consequently, the best grow lights should be good at managing the heat output. If we’re talking generally, then LED lights always come out on top. They emit 50% less heat compared to HIDs. Plus, the majority of this heat comes from the circuit boards, so it doesn’t really go towards your plants at all.

In comparison, HID bulbs generate a lot of heat energy. To make matters worse, this energy is released as Infra-Red radiation into the air. This radiation finds its way straight to the plants.

So, be aware that an HID system will require far more cooling than an LED one. You will most likely need to have a comprehensive air flow system in place alongside it. And depending on the weather in your city, maybe even air conditioning.

If we think back to the first point in this section, you have to factor this into the overall costs.

Ease Of Use And Installation

You might be new to the idea of growing cannabis at home, so maybe you have not installed lights before. As such, you want an option that’s easy to use and can be installed as simply as possible.

Again, LEDs come with an advantage in this domain. The very nature of the bulbs means there will be no lamps to replace ever.

have 40-50% less cooling requirements than un-ventilated HID systems. They create absolutely NO fire hazard in the close quarters of grow tents.

Fluorescent lights are also easy for you to install as they work like normal lighting in your home.

With an HID system, you are going to have about 50% more cooling requirements, and you may have to replace individuals bulbs from time to time. On top of that, if not installed and cared for, they can become a fire hazard in your tent.

If you’re used to setting up “things with cables”, then you may find it easy to install any of them.

Otherwise, if you don’t care about any of this, there are LED plug-and-play kits waiting for you as well.

A lot depends on your personal preference. It’s a good idea to look at specific reviews or see what other people recommend with regards to installation and ease of use.

Best Grow Lights For Cannabis

Finally, the part you’ve all been waiting for! Let’s look at the different types of grow lights and see how they stack up against one another. Then, based on the findings we’ll crown a winner.

LED Grow Lights

 Light Quality & Quantity     
 Ease Of Use     
 Value For Money     
 DrCannabis Rating     
best-led-grow-lights-2020

If I wrote this article a few years ago, then LED grow lights would have been mentioned a lot differently. Technology has advanced in the last few years, making them a great option for keen cannabis growers.

LED grow lights tend to come in a panel format, which is instantly helpful as you get more coverage.

As I have already touched upon, they are incredibly efficient. Especially when you compare them to other lights. This means that you could reduce your running costs if you opted for this variety.

Another key feature of an LED light is that it retains a remarkable amount of brightness. Usually, lights will fade as you use them, the bulb gets weaker with use until you need to change it. LED grow lights don’t suffer from this problem. They stay bright practially forever.

LED grow lights also offer more power than many of their counterparts. While this can be seen as an advantage, it comes with caution about the distance from your plants.

LEDs also happen to be a complete package. What do I mean? Well, you get everything you need all in one place.

They come with built-in cooling systems that stop the lights from getting too hot and raising the room temperature. This is why the best grow cabinet usually come with LED lights.

With other lights, you might need to buy extra things to attach the lights to or connect them. LED lights don’t have this problem as you just plug them in and hang them. That’s all you have to do, so this a great option for first-time growers.

Last, one of the standout features of LED lights revolves around the color spectrum. I’ve spoken about the need to use a combination of wavelengths on the spectrum to get the most out of your plants. Well. LEDs are configured to very specific color spectrum wavelengths.

And some let you switch or tweak the color spectrum yourself. This means you can set more blue light during the vegetative stage, then gradually increase red light moving into flowering.

As such, there’s the potential to get more efficient growth, and bigger and better yields from your cannabis with LED grow lights.

Pros

  • LEDs are incredibly cost efficient grow lights, you'll get back your investment in no time.
  • Pack a punch with high-wattage lights available.
  • Very easy to set up as you need nothing other than a plug socket.
  • Come with a built-in cooling system making them easy to maintain.
  • Comes with customized color spectrum specific for your goals.

Cons

  • Some models can be very expensive when compared to other options on the market.
  • Difficult to get replacement parts meaning you usually have to replace the entire system if just one thing breaks.
 Light Quality & Quantity     
 Ease Of Use     
 Value For Money     
 DrCannabis Rating     

HID grow lights come in different varieties. The two common options for growing are:

  • High Pressure Sodium Lamps (HPS): these lights use a sodium gas discharge to create light. They are most used during the flowering stage of the growing process. Why? Because they create a warm light, which is perfect for bud production.
  • Metal Halide Lamps (MH): here, you have tiny metal halide compounds that discharge to create a light source. MH lamps are known for giving off a nice, bright, blue light. If you’ve been paying attention, then you’ll know this is ideal in the vegetative stage to replicate the bright sun.

In general, HID lights are very strange to look at. The bulbs are weird shapes, and the set-up for them is much longer than the other options. Typically, this stems from one of the biggest concerns – heat production.

HID lights generate vast amounts of heat that can damage your crop. As a result, the bulbs almost always need to be placed in a hood. This prevents a lot of heat from escaping and harming the plants as they grow.

Alongside this, you will probably need to install a cooling system that stops the bulbs from overheating, in the form of an exhaust fan and a vent.

Sound like a lot of work, right?

Well, it is, but there are some serious benefits to going the extra mile.

Once you’ve got passed the set-up process, these lights are surprisingly easy for you to use and look after. Sure, bulbs need replacing now and then, but a key benefit is that you can hang HID lights at the ideals heights.

It’s known what distance is required for specific HID lights based on wattage and so on. We don’t have the same knowledge for the other grow lights, so there’s more guesswork involved when hanging them.

HID lights have the unique title of being the most and least efficient option. It’s the least efficient when it comes to energy costs thanks to all the extra heat that’s generated. Plus the running costs of a fan system, etc.

Still, these lights show great efficiency in terms of yields per watt.

The combination of MH and HPS lights gives you everything you need. You’ve got the blue light to encourage initial growth, then the warm light for flowering.

Pros

  • Provide an exceptionally high yield per watt of electricity.
  • There’s no guesswork when hanging these lights, which means you get the ideal distance every time.
  • Both HPS and MH lights give you the perfect color spectrum for different stages of cannabis.
  • When compared to LED systems (especially new ones) upfront costs should be cheaper.

Cons

  • There’s a lot of extra work required for the installation process.
  • If you’re not careful, then all the excess heat can damage your cannabis plants.
  • The bulbs contain harmful metals that can get into your plants if they break, so that could be a concern.
 Light Quality & Quantity     
 Ease Of Use     
 Value For Money     
 DrCannabis Rating     

Up until recently, T5 lights were used almost only as a supplement. Today, that’s all changed. Modern T5 lights are more efficient than ever, and they have the power you’ll need to take your garden to the next level.

Fluorescent tube lighting is more efficient than other types like metal halide or plasma lights.

Quality T5 lights can generate exceptionally high intensity per watt for this style of light. And tube lights are able to create good amount of brightness without utilizing a ton of power.

This means you’ll be able to maximize yield without increasing your electric bill.

Tube lights are well-known for their long life, these bulbs average about 20,000 hours. And there isn’t much degradation in lighting quality as your lights reach the end of your lifespan.

One of the most crucial aspects of an indoor grow is controlling your temperature. T5 lights generate very little heat, which helps keep temperatures in your grow room down. 

Pros

  • A very affordable option with low purchasing costs and low running costs.
  • Create almost no heat, preventing changes in the air temperature for your plants.
  • Can provide efficient lighting during the first stages of growth as you can place them right up close to the plants.

Cons

  • Not really that effective when plants are tall and bushy or in a crowded during flowering stage.
  • Won’t be suitable if you have to hang them from a tall ceiling as the light intensity isn’t strong enough.

CFL Lights (Fluorescents)

 Light Quality & Quantity     
 Ease Of Use     
 Value For Money     
 DrCannabis Rating     
best-fluorescent-grow-lights-cfl-t5

Fluorescent lights are easily recognizable as you’ve seen them in your home or in random buildings. They’re the long or twisty lights that provide bright light to banish darkness from all four corners of a room. But, they’ve also risen in popularity as a choice for people growing cannabis indoors.

CFL Lights are mainly used when you have limited space available, as they can be kept very close to your plants.

If you’re keen to buy a cost-effective option, then CFL lights might be perfect for you. They’re very easy to get your hands on, and they are the cheapest around.

Additionally, they tend to be efficient as they don’t create much heat energy. This can save you money on your energy bills, but it also means you don’t need to spend a lot to keep the lights cool. You can see why these are popular amongst growers on a budget.

The lack of heat is also beneficial as it can come in handy if you’re using a small grow tent. As I said earlier, you can use CFL lights up close and personal.

This is because they don’t generate enough light intensity or heat to damage the plants. So, you can use them in the early stages to provide a consistent light source to young cannabis plants. It may help them grow better and mature a lot faster.

But, these lights aren’t that great if your plants are tall or in the flowering stages.

While the lack of light intensity and penetration can be good to start with, it becomes a hindrance as the plants get bigger. These lights offer the smallest yields per watt of all grow lights – if you use them in the flowering stage.

So, I recommend only using these in the early stages, then switching to a different light. Or, using them for mini grow rooms or plain flat cannabis crops.

The final thing to note about CFL is that they provide an excellent light spectrum for growing cannabis. You can’t tune the fluorescent lights themselves. But the variety of models means you can buy bulbs across all wavelengths on the spectrum

Pros

  • A very affordable option with low purchasing costs and low running costs.
  • Offer a wide spectrum of colors.
  • Create almost no heat, preventing changes in the air temperature for your plants.
  • Can provide efficient lighting during the first stages of growth as you can place them right up close to the plants.
  • Which also makes it an excellent choice if you have very limited space in your grow room.

Cons

  • Not really that effective when plants are tall and bushy or in a crowded during flowering stage.
  • Won’t be suitable if you have to hang them from a tall ceiling as the light intensity isn’t strong enough.
  • Will need to replace individual bulbs as they get dimmer with use.

Final Thoughts On Grow Lights

After considering everything, it’s clear to see that LED lights are the winners. Why?

If you look at all three options, you’ll see that LED lights have hardly any drawbacks. In fact, the main complaint is that they cost a lot of money.

But, one rebuttal to this is that you definitely make up for this by saving loads of energy while you grow.

LEDs tick all the boxes here. They have the best long-term running costs, they pack serious amounts of power to provide ample wattage. They have a built-in cooling system, and they are so easy to use and install.

Plus, if we look at the importance of the color spectrum, then they come out on top yet again. LEDs are the best lights for tuning to different wavelengths, allowing for optimal growth.

So if you’re thinking about getting the best grow lights for your indoor facility, then LED is the most sensible choice.

Santiago Pardo
Santiago Pardo
I live to help out cannabis growers have a greater experience with their crop, and not lose their mind over the many aspects of growing marijuana.
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