Medically Reviewed by
Jason Crawford

Article Last Updated on January 7, 2023

For weed growers who aren’t able to cultivate marijuana out in the open, growing indoors is the next best thing (if not better, in some cases). Both methods have their perks, and the perk of growing indoor plants is that you get to control all the growing conditions, from humidity and temperature to lighting. This allows indoor growers to help their plants reach their absolute maximum and end up with a nice and rich yield.

Choosing the lighting system for your grow room is one of those make-or-break decisions for your marijuana plants. Cannabis is a photoperiod plant and light is essential for each phase of its growth cycle because light helps it produce food, so choosing the best grow lights is essential. Of course, all indoor growers have their own preferred way of cultivation, so you’ll need to choose your light system according to your grow space and preferences. 

In this article, we’ll discuss the pros and cons of the major types of growing lights to help you make an informed decision when the time comes for you to choose the best lights for your plants.

Growing Cannabis Plants Indoors Is Easy When You Have the Right Lighting System

When choosing grow lights, the light spectrum needs to be carefully selected. Sunlight has a full spectrum of colors, meaning that it contains red, blue, and orange sectors that stimulate photosynthesis and the production of chlorophyll, among many other processes. This is how light affects the growth of the plants, so as an indoor grower, you’ll need to find lights that can mimic natural sunlight.

The most crucial thing to remember about the light spectrum and marijuana plants is that the blue spectrum in lights promotes vegetative growth, while the red spectrum is necessary in the flowering phase. Depending on which phase your plants are in, you’ll have to adjust the lighting system accordingly.

The Right Amount of Light Is Essential for Plant Growth

You may think that growing marijuana outdoors is much less complicated than growing indoors, but this is not entirely true. Growing outdoors has its own challenges, like facing pests and unpredictable weather and temperature changes. 

On the flip side, with indoor growing, you won’t face these challenges as most cultivators use hydroponics which lowers the risk of pests and infestations. With indoor growing, you get to control everything, which also means that making the right decisions for your plants will be crucial. 

First things first – you should know how much light your crops need every step of the way. Light is necessary for photosynthesis which helps the plants synthesize food in order to survive and fuel their growth until harvest.

With indoor grow lights, you need to follow the natural cycle in nature – cannabis is planted in spring when the hours of light are starting to increase, and it’s harvested in late summer/beginning of autumn when the hours of light start to decrease.

Therefore, marijuana plants need different cycles of light and darkness depending on what phase of growth they’re in.

Typically, they need more hours of light than darkness during the vegetative stage (18 hours of light and 6 hours of darkness), while during the flowering stage, the hours of light and darkness are equal (12 hours).

The Pros and Cons of Different Types of Grow Lights

Choosing the light source for your marijuana plants will largely depend on the size of your grow space. If you have a small space, you should use smaller lights (like fluorescent lights or smaller HPS grow lights). On the other hand, if your grow room is large, you can set up larger equipment and even experiment with different types of setups.

However, it’s equally important that you plan out everything well beforehand, as your plants will need different types of light during different growth phases. In general, HID lights are suitable for both the veg and flowering phases, while MH lights are more suitable for the vegetative phase. Therefore, being realistic about what you can achieve and making the best use of your space is the best way to get your plants thriving.

There are three main groups of grow lights: LED lights, HID lights, and fluorescent grow lights. Let’s see what each of them has to offer.

LED Lights

LED grow lights, or light-emitting diodes, are perhaps the most commonly used lights for indoor growing.

They’re designed to be low voltage, which means their energy consumption is low and you won’t spend a fortune on electricity bills and upkeep. They also generate less heat than other types of grow lights, which will protect your plants from light burn. Another plus is that most of them are full-spectrum LED lights which will ensure you get the maximum performance out of your plants.

The downside is that the light intensity of some LED lights can be quite low, possibly due to the low energy consumption. Additionally, their price can be off-putting at first. Technically, the initial cost is higher than other types of grow lights, but the long-term payoff will be greater. Cheap LED grow lights are not worth buying as their quality isn’t on par, and will stunt your plants’ growth. 

HID Lights

HID (high-intensity discharge) lights are used for the indoor cultivation of various plants, cannabis included. They are energy efficient while still being very effective. They are also dimmable, which allows you to modify the light output according to the plants’ needs. The downside of HID lights is that they generate a lot of heat, so you’ll need to place them at an appropriate distance from your plants.

There are three types of HID lights – metal halide, high-pressure sodium, and mercury lights. The lumen to watt capacity of mercury lights is too low compared to the other two, so we will exclude them in this selection.

MH Lights

MH (metal halide) lights emit blue light which makes them great for the vegetative stage of cannabis plants as they’re able to help the plants grow optimal foliage. The light bulbs are a little oddly shaped and need to be screwed on a reflector or hood to cast more light onto the plants.

HPS Lights

HPS (high-pressure sodium) lights emit yellow light which is just what marijuana needs in the flowering stage as they stimulate the production of buds. There are different wattages of HPS bulbs, but you should never go very high, otherwise, you’ll burn your plants. A wattage of 400 to 600 w would be the right choice.

Fluorescent Lights

Fluorescent grow lights are versatile in that they can be found in different spectrum colors – blue, red, or full spectrum. These grow lights are cheap and they provide nice lighting for indoor plants. However, they are also not as powerful as other types of grow lights so they can’t be used in larger grow spaces. They work best in smaller grow rooms where you can position them close to the plants.

The two types of fluorescent lights are compact fluorescent lights and T5 lights.


CFL (compact fluorescent lights) can be easily found anywhere. They’re very suitable for novice growers who don’t know a lot about cannabis cultivation. They work best for low-key growing in very small spaces where no other type of light bulb would fit. Another plus is that they don’t emit a lot of heat, therefore minimizing the odds of light burn, so make sure to place them close to the plants.

T5 Lights

T5 lights are much bigger than CFLs, about 2-4 ft long, and they’re normally attached to a panel. The “T” stands for tubular, while the 5 refers to 5/8 inch of diameter. They also don’t generate a lot of heat so they should be placed not too far from the plant. Another plus is that they have a longer life span – about 20,000 hours. The cons are that they won’t always generate a high yield, especially if you use them during the flowering phase.

Bottom Line – Choosing the Best Grow Lights for Your Plants Is an Essential Part of Growing Cannabis Indoors

If you’re a beginner grower, it may seem very complicated to choose among so many grow lights, but don’t worry, you don’t have to rush it. The most important thing before you make your decision is to first evaluate your space and how many cannabis plants you can fit in there. The second most important thing is to do thorough research on grow lights and their upkeep before you make any decisions. Happy growing!

A passionate advocate for the benefits of cannabis. Fraser Horton, who has a background in botany and a strong love of nature, has spent years researching how cannabis affects the body and mind. He established Leaf Nation in 2020, where he has devoted himself to educating people about the legalisation of marijuana and its safe and responsible use. Fraser is committed to highlighting cannabis’ potential for improving wellness and working to dispel the stigma associated with its use.


The information presented on this page is provided as a public service to aid in education and is derived from sources believed to be reliable. Readers are responsible for making their own assessment of the topics discussed here. In no event shall Leaf Nation be held reliable for any injury, loss or damage that could happen if using or abusing drugs.