What are the best indoor grow lights for cannabis, and why?

Discussing 5 popular types and what makes each of them great

Growing cannabis indoors comes with a whole list of benefits, along with its own set of challenges.

You can now start cannabis cultivation at any time of the year and speed up the growth process significantly. Also, when growing outdoors, the sun isn’t always optimally available in cases of bad weather or badly timed season of the year. 

Growing cannabis indoors enables you to take control of your environment completely, if you know what you’re doing, you can get some pretty big quality harvests. You’ll have super consistent growth due to the fact that you’ll have control – temperature, light, CO2 levels and humidity. You won’t even have to worry about changes in the weather. 

The trick comes in knowing what kind of light your plants need at different stages of their growth phases. Having grow lights that produce the right light spectrums will prove very beneficial to your harvest.  

Types of indoor grow lights

There are 5 general categories of lights that are all excellent to grow cannabis indoors – all affecting your plants differently. 

Some are applicable for start up; aka seeding and root trimming, while others work better for the vegetation and flowering phases. 

Luckily, the surrounding technology all has grown so much that today you can purchase full spectrum lights or a combination of two, so you only have to buy a single grow light. 

Full spectrum lights provide light in virtually any colour temperature, including daylight. 

In short, growing cannabis at home has become a lot more accessible to people. 

Fluorescent & CFL

Fluorescent lights are ideal for cultivating your growth operation during stages of seed sprouting and root cuttings. 

They’re not ideal for larger crops as they’ll need frequent bulb replacement (shorter life span) which can be costly and time-consuming. They also don’t produce sufficient heat for optimal growth. 

Growing marijuana plants need warmth and efficient light penetration of the right spectrum, and since fluorescent lights don’t produce enough heat or sufficient light to penetrate the plant’s surface as needed, they’re not ideal past the cultivation stage.  

You can find out more on choosing the perfect seeds & strains for you personally, here.

HID – high intensity discharge 

The gold standard grow lights of the cannabis community and an umbrella term under which MH and HPS bulbs fall (more on that below). Many people swear by HID lights and believe they produce the biggest yields. 

They’ve been the standard growing lights for cannabis for decades, although LEDs are quickly catching up these days. 

Both types of HIDs are surprisingly inexpensive, produce a lot of light and heat but use a considerable amount of electricity. Remember, they run hot, contain heavy metals, and ballasts can fail. 

Because of their overall price, buying an HID light as a first-time grower might be your best bet. 

Metal Halide aka MH

MH lights are suitable for the vegetative stage. 

They typically emit a white coloured light and have been used by growers for years to get their cannabis plants up to pre-flowering stages. They mimic the spring/early summer sunlight spectrum. You can also find lights in much greater wattage than fluorescent and CFL lights. 

In order for cannabis to grow optimally, they require a combination of both MH and HPS lights for their different stages of growth. 

It’s important to note that this kind of light needs a ballast to operate, which are often compatible with both MH and HPS lights. If you’re going to use the same ballast for both vegetation and flowering stages, be sure to check your wattage when replacing the lights. Use 400w bulbs with 400w ballasts and so on. 

Metal Halide lamps are commonly found in 250, 400 and 600w. 

MH lights produce excellent results in the pre-flowering stage (first 1-3 weeks of flowering) thanks to their light spectrum. This helps prevent stretching of the plant in comparison to HPS lighting, creating plants with a more stocky structure and optimally preparing them for abundant flowering. 

HPS lights

Without a doubt, HPS (high pressure sodium) lights are the most popular and effective for the flowering stage, or at least they have been for years. LEDs are also quickly catching up in this category. (Below, we discuss LED lighting in detail) 

HPS bulbs provide the perfect light spectrum to stimulate the flowering stage. 

They are the overall suggestion for when you want to use a single type of light throughout your entire growth process (before LEDs & CMH) instead of switching lights as the stages progress, as is optimal. You still face its heat emission problems and the fact that its light spectrum is not entirely adequate for proper overall growth. Many users use air-cooled tube reflectors to cut down on a few degrees in room temperature. 

There are also HPS mixed light (dual spectrum) lights available for both growth and flowering, or specifically for the last phase. 

You can find HPS lights in 250, 400, 600 and 1000W. Generally, the 600W option would work best for spaces greater than one square meter.


Popularly spoken of as the next evolutionary step in indoor lighting for raising crops.

It boasts full-spectrum lighting, meaning it has all the necessary wavelengths in just the right proportions to optimise your plant’s growth from seeding to harvest. In addition, it also provides enough heating; more than LEDs but less than HPS.

It might be advisable to decide on your ideal growth period. CMH (ceramic metal halide) lamps last 20 000 hours, compared to LEDs that last 50 000 hours.

Choose CMH if you’re aiming for a shorter grow period of 1-2 years, whereas LEDs will be your better fit for a 2-5 year period. 


Cannabis grow lights used to be the most expensive part of a growing operation, but with the improved technology of LED lights these days, you can get away without paying that much in terms of power consumption or initial purchase price. 

LED (light emitting diode) grow lights are available in full spectrum wavelengths, they just lack heat emission. This can be rectified by heat mats or heating cables etc. 

How many lights are required for growing cannabis?

One or two will do the job, in most cases. It depends on which lights you use (a single type for the entire growth process or multiple types throughout different stages of growth) as well as crop size. 

South Africa’s cannabis law currently allows 4 plants per adult on a property / in a house. 

In a case where you plan to vegetate and flower your plants in separate rooms with separate lighting setups, you’ll definitely need 2 or more lights.  

What to consider when choosing cannabis grow lights


First things first – you’ll have to decide on your budget. After that, consider how often you’ll be completing a growth cycle.

Apart from that, you’ll need to make sure you’re aware of the electricity costs that come with using certain lights. HIDs consume a considerable amount of electricity, but are cheaper in general. 

LED’s on the other hand, are slightly more expensive to purchase but use much less electricity. 

Consider the cost of fans for cooling if you’re using an HID light with high heat emission. 

Plant Growth

You’re going to want to choose a full spectrum light or something that can carry your plant through the various stages of growth. Whether it be a dual spectrum or two separate lights, it’s something you have to decide beforehand if you want a good harvest. 


When growing cannabis indoors, you should be aware of high heat emission that comes with some HID lights. You can prepare for this with sufficient ventilation and air-cooled tube reflectors. And of course, electric fans. 

What are the best lights for growing cannabis indoors?

If you’re going with the times and want the process simplified, opt for an LED or CMH light, depending on how long you plan on growing for.

Remember, LEDs last much longer than CMH lights. 

If you’re growing cannabis at home and plan on moving your plants to a different space as they progress, you could also use MH (for vegetation) and HPS (for flowering) or simply stick to full spectrum lights throughout. 

These are especially useful as they closely replicate light from the sun, and you can change the light spectrum by the turn of a knob. 

We hope this has been helpful, good luck growing!