If you’re growing cannabis indoors, quality of light is probably the biggest factor affecting your yield and potency. But which cannabis grow lights should you choose? Which lights produce more yield, and which lights produce higher potency?
This is our ultimate guide to choosing the best cannabis grow lights for your grow room or tent. It is based on over a decade of experience growing high quality cannabis for Colorado medical marijuana patients that demand a potent, high quality product.
Choosing the Right Cannabis Grow Lights
Quality of light is one of the biggest components to growing high quality cannabis. You need to be powered properly for your grow space, and have the right spectrum of light for cannabis plants during vegetative and flowering stages of growth. But how do you know which light to choose?
There are a number of factors to consider, including the size and height of your grow space, your budget, and your intended yields. We will present a variety of options for you based on all of these factors.
Generally speaking, more light equals more yield, up to a point. It is possible to burn your plants with too much light. More light plus abundant nutrient availability (the right level of nutrients in your growing medium at the right PH) equals ideal growth.
Watt for watt, most cannabis grow lights generate a similar amount of light, draw a similar amount of electricity, and produce a similar amount of heat. However, there are clear benefits and drawbacks to each type of light.
You might be wondering how each grow light will affect your electricity usage, heat output, and yield / potency.
- Electricity — Despite what manufacturers say, most cannabis grow lights have similar output for electricity draw.
- Heat — Most grow lights put out similar levels of heat for their energy consumption. The main difference is that CFLs tend to run pretty hot, HID grow lights can be put inside a reflector hood or tube where you can run exhaust fans straight through the light fixture, and LEDs tend to run a bit cooler and many can be placed near-field, that is, closer to your plants.
- Yield & Potency — Generally speaking, if you’re looking for high yields and relatively inexpensive cost, HID lamps are the way to grow. A lot of growers say they can produce great potency from full spectrum LEDs, but that the yield is somewhat less. Many growers supplement their HID lights with LED to find a nice middle ground.
Fitting your Light to your Grow Space
The first thing to consider is the size of your grow space, and your budget. If you’re limited on size and plan on running less than 150 watts, then compact fluorescent lights are your best bet. There’s even an entire Subreddit dedicated to “Space Bucket” CFL grows — compact grows made out of 5 gallon buckets.
Here’s a basic guide on which cannabis grow lights are suitable based on wattage.
- less than 150w = CFL or LED
- 150w – 400w = HID or LED
- 600w – 1000w = HID or LED
- more than 1000w = Double Ended HID or commercial LED
But how much square footage can you grow with each type of cannabis grow light?
- 150 watts = 4 sq ft
- 150w – 400w = 6 to 10 sq ft
- 600w – 1000w = 16 to 32 sq ft
- Large scale = a single DE light can cover a 36 sq ft area.
*note: T5 lights cover about the same area as the light fixture, so a 4′ x 1′ T5 fixture will cover about 4 sq ft (we use these for our veg rooms only).
And how much cannabis can you grow with each setup?
- 150w = 2 to 6 oz
- 400w = 8 to 12 oz
- 600w = 12 to 18 oz
- 1000w = 1.5 to 2 lbs
(these are averages, some strains yield more than others, and it depends on nutrients, deficiencies, CO2, temperature, humidity — and more)
The Four Main Types of Cannabis Grow Lights
There are four main types of marijuana grow lights: fluorescent, high-intensity discharge (metal halide, high-pressure sodium, and light-emitting ceramic), light-emitting diodes (LEDs), and induction lighting. What’s important to know about each one?
It’s pretty simple:
Fluorescent cannabis grow lights are very energy efficient and work well for small grows and vegetative growth if you’re running a continuous operation.
HID lamps work great for both vegetative and flowering stages of growth. Metal halide grow lights put out a very blue light for vegetative growth, and HPS is more orange/red for flowering. Ceramic metal halide, on the other hand, is more full spectrum, natural light.
LED lights, while expensive, are a great cross between the two and have a much longer life (HPS bulbs need to be replaced every year)
Induction lights (magnetic or plasma) are great for optimizing the vegetative rooms on a large scale grow where efficiency and consistency of light output is necessary. They are basically more expensive versions of fluorescent lights with a much longer life span, but they never really took off in the industry.
Here’s the complete breakdown.
Fluorescent Grow Lights for Cannabis
There are two main types of fluorescent lights used for growing marijuana. The first is the T5 fluorescent linear tube, which is used often in commercial grows. There is also the CFL, or compact fluorescent light bulb, which is used in micro grows, often in a space bucket or PC grow. (as a disclaimer, we don’t have any experience growing through flowering with CFLs, so take our advice on them with a grain of bubble hash).
T5 Fluorescent Grow Lights
T5 fluorescent lights are the standard 48” long thin white bulbs you see in most businesses. They produce a very consistent white spectrum of light and are super energy efficient, meaning they are cheap to operate.
The T5 refers to its diameter: ⅝” of an inch. These lights are very common because they produce a large amount of light for the energy used, and they can be placed very close to your plants without worrying about light burn. T5 s are also great for clones and young marijuana plants that are very sensitive to high intensity light.
If your grow operation is continuous, meaning you have both vegetative and flowering rooms growing simultaneously, you’ll get the most bang for your buck using T5 fixtures in your veg room.
- Cheap setup, easy to maintain
- Won’t burn your young cannabis plants
- Not for flowering growth
- Bulbs burnout randomly and you’ll need to have replacements on hand
Our Top Choice: Sun Blaze T5 HO Fluorescent 120 V 4′ Light Fixture.
- Wider advanced reflector design offers excellent reflectivity and diffusion. Excellent light source for growing plants.
- White powder-coated steel housing
- Wire cable hangers and v-hangers included which allows fixture to be hang horizontally or vertically
It comes in many different sizes to fit any size clone and vegging room. It also features two on/off switches so you can run only 4 bulbs at a time if needed (for cloning).
Sun Blaze fluorescents are built by Sun Systems out of Vancouver, Washington. This fixture might be a little more costly than other T5 panels, but we’ve used them extensively in our medical grows and can vouch for their durability. You can daisy chain them together which makes for simple cable management.
Next Best: Hydrofarm Agrobrite 4’ x 2’ T5 Fluorescent System.
- 3"H x 26"W x 46"L
- Includes 10' grounded power cord
- Includes 8 6400K T5 Tubes
This is a relatively inexpensive version of a T5 fixture. Some users have reported ballast failures within a year or two, but if you’re on a budget this could be a great interim fixture while you save up for something more reliable.
Compact Fluorescent Grow Lights (CFLs)
If you’re planning a very small scale grow (less than 150 watts) then you can get very good results from compact fluorescent lights. However, your yield and potency will suffer because they lack the ideal photosynthetic light spectrum for cannabis growth.
But that’s not to say you won’t enjoy the end product! We really enjoy watching other growers build out PC grows and Space Buckets using CFLs for their entire growth cycle.
The setup is a bit more labor intensive as light fixtures for CFLs aren’t designed to be used in grow tents or 5 gallon buckets, so you’ll have to do a bit of wiring. Luckily there are some great online tutorials.
- Ideal for small setups like PC grows, space buckets, and small tents
- Energy efficient and cheap setup
- Can be placed very close to your plants
- Not the best yield per watt
- Not the ideal spectrum for flowering, which decreases potency
Our Top Choice: Hydrofarm Agrobrite 125 Watt CFL with Reflector.
We’ve always kept at least one of these around in case a friend brought over some clones and we needed some extra space.
- Fluorowing compact fluorescent daylight system with dew guard
- Full daylight spectrum incandescent grow bulb
- 120-volt, 60-hertz frequency with mogul base type
However, if you are just looking for the best quality CFL bulbs for your space bucket or other custom grow…
Next Best: Sun Blaster CFL 6400K daylight bulbs
- GROW LIGHTBULBS: Use for indoor plant growing all throughout the year; replicate the sun’s natural light anywhere in your home
- WHAT'S INCLDUED: Includes 4 individual 13 watt CFL bulbs that have a temperature of 6,400 kelvin
- ENERGY EFFICIENT: Compact fluorescent light is energy-efficient and produces 900 lumens
High-Intensity Discharge Cannabis Grow Lights
These are the industry standard, and for good reason. With one fixture, you can use a metal halide lamp for vegetative growth, and a high-pressure sodium lamp for flowering. This means you can have one tent for both stages of growth, and one light fixture that does it all. Ceramic metal halide are full spectrum, meaning you can use them for both vegetative and flowering stages of growth.
Many of these fixtures, like a reflector hood or tube, have the ability to have exhaust tubing connected to either side, so that you can actively cool the light system, which can generate a lot of heat.
HID lighting comes with a ballast, i.e. a power brick. We suggest a digital ballast as they have better longevity and don’t create magnetic fields that mess with your wifi or cell phone. Ceramic metal halide fixtures contain a self-contained ballast, which makes it a little more convenient.
- Relatively cheap to setup and install
- Great for high yield 400w to 1000w setups
- One light fixture for both stages of growth
- Best bang for your buck
- HID lights run hot, requiring a venting / exhaust setup
- The light bulbs have to be replaced every year and can be expensive
- Cannabis flowers look strange under HPS light (we suggest light filtering grow glasses)
Metal Halide Grow Lights
Tungsten metal halide light bulbs output light in the blue and violet spectrums that is very similar to the light outdoors during spring. This light spectrum is ideal for rapid vegetative growth for young cannabis plants.
The blue spectrum of light encourages compact, leafy growth and encourages the plant to develop a strong root system.
High Pressure Sodium Grow Lights
High pressure sodium light bulbs output light in the yellow and red spectrums that is more similar to autumn lighting, which promotes blooming and flower production. This light spectrum encourages flowering because it signals to the plant that winter is coming!
The plants stop producing root systems and focus on producing flowers so they can be pollinated and the plants seeds can carry on another generation in the spring. However, we will prevent the pollination and enjoy the beautiful cannabis flowers.
You see HPS lighting nearly everywhere, as they are used for night-time road lighting on highways and neighborhood streets.
Our Top Choices: Sun Systems 150 Watt High Pressure Sodium.
This light is an all-in-one fixture and comes with a reliable HPS lamp for growing small scale. It requires minimal setup but we do recommend a little bit of climate control, as it can get pretty hot in a small space.
- Lightweight, complete grow fixture, easy to set-up and use
- Grow your own vegetable, herbs and flowers indoors
- Simulates natural sunlight for maximum plant growth with 16,000 lumens
The 150w HPS can be a bit overpowering for young cannabis plants, so we recommend getting a solid CFL light like the AgroBrite listed above, then switching to HPS for flowering.
iPower 400 Watt Cool Tube Reflector with Digital Ballast
- 400W Digital Dimmable Electronic Ballast: Support 120V/240V Input; Dimmable Options: 50%, 75%, 100%; 8 Feet heavy-duty power cord included; Stable power output ensure flicker free light
- 1 x 400W Super HPS Bulb 2100K; 1 x 400W MH Bulb 6000K; Optimized spectrum and high PAR (Photosynthetic Active Radiation) to promote healthy plant growth and soonest flourish
- 1 x Pair of 8-ft adjustable Ratchet Clip Hanger Rope: hold up to 150 lbs; 24-hour Plug-in Mechanical Timer: 15 minutes increments
For $170, you can’t beat this iPower setup. It will power a 2’ x 4’ tent and you’ll be surprised at the yield and density of your nugs. We’ve regularly seen 1 gram per watt out of a tent that size. Keep in mind that this will generate enough heat to make it close to 100° in there so you’ll need some ducting and an inline fan.
There’s also a 600 watt and 1000 watt version.
For Professionals: Gavita Pro 1000e DE Lamp 120v / 240v
- Controllable output: dim or boost your light to adjust it to changing circumstances or grow phases
- Soft dim which gradually changes the output when switched, eliminating stress on the lamp
- Lights more than 2 square meters with 1000 μmol m-2 s-1, No electromagnetic interference problems through the integrated design
This has been our go-to professional fixture for years. It covers a 6’ x 6’ area and we averaged 2-3 pounds of high quality medical grade cannabis per light. They’re not cheap, but these bad boys are super reliable.
Ultimately, there’s a reason that HID lights have been the industry standard for cannabis grow lights. They work, they’re relatively inexpensive, and they produce a high quality product. HID lighting remains highly relevant in the commercial cannabis space and we suggest you start here for your first home grow.
Ceramic Metal Halide (CMH) Grow Lights
Ceramic metal halide grow lights, also known as light-emitting ceramics, are a relatively new full spectrum lighting fixture. This means you can use one bulb for vegetative and flowering stages of growth.
These fixtures are more expensive than a typical HID setup, but the light is much closer to natural sunlight than metal halide, which emits a very thin spectrum of blue and violet light, or high pressure sodium, which emits a very thin spectrum of yellow and red light.
We’ve used these off and on for small-scale grows, and have been really happy with the potency and yield.
- Full spectrum lighting means more aggressive growth
- Better PAR output per watt
- One bulb for vegetative and flowering stages of growth
- Increased potency and solid yield
- UV-B for increased trichome production
- Natural color light allows you to spot nutrient deficiencies quicker
- More expensive setup
- More difficult to cool
- You’ll need UV protection if working in an LEC grow for extended periods
Our Top Choice: Sun System LEC 315
- Non air-cooled
- Weight: 12 lbs
- Country of Origin: China
This light will absolutely dominate a 3’ x 3’ tent (you can stretch it to a 2’ x 4’ but in our experience, the plants furthest from the light tend to get a little airy). When you put seedlings or clones under an LEC, keep the light about 36” away, then slowly lower it to about 18” – 20” for optimal growth once the plants are strong.
LED Grow Lights
LED grow lights have been on the scene for over a decade now, and are a popular choice for small-scale growers due to their effectiveness. There’s no need to change out lamps, and the LEDs last for many more grow cycles than HID lamps do.
Another added benefit is that LED grow lights run a lot cooler than HID lamps, making them ideal for a small scale grow where keeping the area cool may be an issue. However, they do cost more upfront.
There are many variations between true PAR output from cheap manufacturers, so you have to do your research. Manufacturers also market these panels using strange watt ratings. For example, if an LED fixture has 100 x 10 watt LEDs, this may be marketed as a 1000 watt LED grow light! This is intended to confuse potential buyers, because it may be marketed as a replacement for a 1000 watt HPS, but the light only draws 150 watts.
Our tip: always look to see the power draw and effective coverage.
“Blurple” LED Grow Lights
The internet has blessed these LED grow lights with the name “blurple” due to the combination of red and blue LEDs making your grow room look, well, a combination of blue and purple.
There are a lot of substandard “blurple” LED cannabis grow lights on the market, because manufacturers realized they could use cheap LEDs and build a light that looks professional while charging a premium.
A lot of these panels are substandard, because they are made with only the cheapest SMD (surface-mounted) LEDs on the market — those that output a very narrow band of red and blue light. Higher quality lights will actually add some UV spectrum back-in.
Due to this, we’ve seen a lot of home growers use a “blurple” LED panel to assist their HID lighting, and while we’ve seen some full “blurple” grows achieve solid results, the yield is not as good as HID lighting, but growers report solid potency.
- It looks cool
- High potency
- Yields will suffer
- Hard to know which manufacturer to pick
- Good blurple grow lights are expensive
- Difficult to replace LEDs if / when they burn out
Our Top Choice: ViparSpectra V900
- VIPARSPECTRA Reflector Series V900 LED Grow Light is scientifically engineered to keep the balance of the PAR Output and Coverage.
- Optimal Spectrum: The secret to VIPARSPECTRA’s success is optimal full spectrum lighting which provides plants in all stages from veg to flower with everything they need in the natural sunlight. This results in bigger buds and higher yield all while saving you on energy costs.
- Outstanding Design: Sturdy durable construction with fire-resistant iron housing. Dimmbale feature allows precise spectral control and suitable for each growing phase. Upgraded aluminum cooling heat sinks and advanced high speed quiet fans are great for heat dissipation.
This is one of those cases where the manufacturer calls it a 900 watt fixture, but it actually pulls close to 400 watts. That means it works in a 2′ x 4′ grow area maximum.
Next Best: Phlizon CREE 2000W LED Grow Light (true power 400 watts)
- CREE COB LEDS- CREE COB is known for high power and stability. CREE COB, higher brightness, smaller thermal resistance, less light attenuation and longer life.CREE COB itself is a full spectrum design with high PPFD value which can promote faster and better plant growth
- EXTREMELY HIGH PPFD- PPFD, Photosynthetic Photon Flux Density，Hanging at 18", the PPFD is 941 umol/m²s. The bigger the density, the higher the value, the better the plant. COB LED has highest PPFD output. COB LED is much brighter and more efficient than traditional LEDs.
- FULL SPECTRUM- The CREE COB LED itself is a full spectrum lamp integrated design bead. We have added additional light beads in various bands to ensure the scientific full spectrum. It contains 4pcs COB, 68pcs 630-660nm, 10pcs 470nm, 6pcs 6500k, 4pcs 3000K, 4pcs UV, 4pcs IR
This light even has some full spectrum LEDs built in, which makes it a contender. It does have built-in fans, so it can be on the noisy side but it’s also very good at dissipating heat.
Full Spectrum LED Grow LIghts
Recently, a new LED grow light technology has hit the market: COB LEDs, or Chip-on-Board LED grow lights. These have been game changers, not just for budget-oriented home growers, but for the commercial grower as well.
Full spectrum LED grow lights put out light that is closer to the sun’s light, and many of them have additional UV spectrum LEDs built-in to give your plants that added boost. Additionally, the setup of these LED fixtures in a “quantum board” configuration means more even light across your entire canopy, leading to more consistent yield and potency.
Again, there are a lot of players on the market and a bunch of cheaper options that will reduce your yield and potency, so it’s important to do your research here. Many of the cheaper panels use Epistar LED chips (or even cheaper manufacturers), while higher end professional panels use Samsung, Philips LumiLED, or OSRAM.
- Natural, full spectrum light
- Yields similar to HPS
- Long life
- Near field light – you can hang them 12” – 18” away from your plants.
- Quality lights are expensive
- Difficult to replace COB LEDs when they burn out (but not impossible if you have some soldering experience
- Manufacturers may use hard to understand watt ratings
Our Top Choice: Electric Sky 300 V2
- READY TO GROW BIGGER AND FASTER? The Electric Sky’s WIDE BAND FULL SPECTRUM gives plants the perfect PAR across your ENTIRE grow area with spectacular canopy penetration. The Electric Sky not only shows plants in true color for your eyes, but is also scientifically tuned for rapid plant growth.
- MAXIMIZE YOUR GROW SPACE with near-field lighting technology. Special dual-direction linear optics focus light away from your eyes and onto your plants. The larger, distributed LED footprint gets our Electric Sky 12-15” from your plant canopy so you can grow HIGHER and WIDER in tight spaces without burning or dead zones.
- GROW ANYWHERE with silent cooling and operation. NO FANS to break down! Ultra-high efficiency means more growing power so you can grow bigger plants with less heat to deal with and energy costs.
This light is absolutely killer in a 2’ x 4’ tent, and it’s also a near-field grow light so if you’re tight on vertical space, this is a game changer. The light draws 300 watts of power and is passively cooled, which means no noisy fans. It’s expensive but you will love the quality and consistency you get with this cannabis grow light.
For the professional: Spec Grade LED Verta 8
For commercial grows, the Spec Grade Verta 8 is a 48” by 48” modular full spectrum panel that draws 600 watts. Spec Grade uses a proprietary blend of Samsung, OSRAM, and Philips LumiLED chips. They aren’t cheap, but if you’re looking to grow the best high quality cannabis commercially, these are top notch. They also sell inter-canopy lights and have a 10 year warranty.
Induction Grow Lights
Induction grow lights are basically fluorescent lights without a filament. They use the principle of electromagnetic induction to excited particles of gas in a tube to generate light (and heat).
Because the filament in a fluorescent tube is typically the first part to wear out (after 10,000 to 20,000 hours) — induction grow lights can last much longer, up to 100,000 hours. They also generate more photosynthetically useable light than fluorescent lamps, but this is only important if you’re trying to maximize the vegetative cycle of your cannabis plants.
For example, a commercial grow might find it important to use induction lights over fluorescents because they need to put plants into flowering after 4 weeks in order to hit yield targets, whereas a home grower can just leave their plants in the vegetative stage until they are the perfect size for flowering.
Magnetic Induction Grow Lights
Magnetic induction grow lights use nearly the same gas as a fluorescent light, a low-pressure mercury vapor. The energy current excites the gas, which creates short-wave ultraviolet light that causes the phosphor coated glass to glow. Wow! Sounds pretty cool.
Plasma Induction Grow Lights
Plasma induction grow lights use the same principle of magnetic induction to drive the light, but instead of a magnetic field, they generate microwave radiation that excites a sulfur gas in the form of plasma.
It’s important to note that these lights can mess with your Wifi and cell phone signals when working near them, so that is a downside to both home growers and commercial grows.
- Longer life than T5s
- More consistent PAR throughout the lifecycle
- You can talk about “plasma” when telling friends about your grow
- More expensive
- Not necessarily more effective
- Cell phone / wifi signal interference.
Our choice: we’ve only experimented with the AgroMax Pure PAR Induction light. We never found a benefit over using cheaper T5 or LED fixtures for vegging our cannabis, so we went back to those.
Make the Best Choice for Your Budget
If you’re just starting out, we recommend getting a cannabis grow light that fits your budget. Any of the HID or LED grow lights listed above will grow quality cannabis regardless of whether you’re nerding out on the PAR and spectrum details or not.
If you’ve been buying your cannabis from the dispensary, you’ll be saving a lot more money over the long term by growing your own supply. This is money that you can invest in more advanced cannabis grow lights and equipment to maximize your yield and potency.
So there you have it, a complete breakdown of cannabis grow lights for your home cannabis grow, and some commercial options thrown in.
This is our way of giving back to the community and helping you develop your own “secret sauce” to grow your own high quality cannabis at home. This site is a free resource, so if you’re planning to buy one of the options above, we’d appreciate it if you click on one of the affiliate links sprinkled across the page. We get a small commission to help grow the site, and it costs you nothing (and we really appreciate it).
Last update on 2021-02-27 / Affiliate links / Images from Amazon Product Advertising API