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Grow lights are essential when growing cannabis indoors. The grow light acts as a replacement for sunlight, providing your plants with light and heat. Grow lights are one of the most important tools to growing cannabis plants indoors, but with so many different types of grow lights available, it can be overwhelming for a new grower to decide which one to choose.

Factors to consider before selecting a grow light

These are some factors that will help you when deciding on the best grow light for you.  

Your Budget

This is an important factor to consider when grow light shopping. You will need to determine how much you are willing or capable of spending, as your budget will often determine which type of light you end up buying. The price of grow lights will differ depending on quality, type and brand. Investing in a good quality light can be an expense initially but will prove to be a good long-term investment.

The Grow Area

Another important factor you will need to consider is how much area you actually need to cover. This will depend on how big your grow space is. If you have a large grow space, you might have to purchase multiple lights to provide the correct amount of coverage for your plants to grow. If you only plan on growing a few plants in a small grow tent, then you could get away with only using one grow light.

The Phases of Plant Growth      

A cannabis plant needs specific light spectrums in each stage of growth. Some grow lights on the market offer 'switches' which help the plants in every growth stage. Different grow lights on the market also have different light spectrums such as blue light, red light, dual spectrum, and full spectrum.

   

Understanding the Different Spectrums

Blue Spectrum

Grow lights with a spectrum containing mostly blue light are used in the vegetative stage as blue light promotes healthy growth of leafy green foliage and strong stems.

Red Spectrum

Grow lights with a spectrum containing mostly red light are used in the flowering stage as red light promotes bud development.

Dual Spectrum

Lights that are dual spectrum contain blue and red light. This means they can be used during the vegetative and flowering stages.

Full Spectrum

A grow light that is full spectrum will deliver light across the entire visible spectrum of light from infrared to near-ultraviolet. This type of lighting closely mimics the UV rays from the sun. These types of lights are considered advanced, so they are often the most expensive.

   

Main types of grow lights

There are three main types of grow lights: high-intensity discharge (HID), light-emitting diode (LED) and compact fluorescent lights (CFL)

 

High-Intensity Discharge (HID)

 

HID lights have long being considered the gold standard in grow lighting as they are known to produce the highest yields. HID lights emit a lot of powerful light energy and provide good coverage in your grow area. HID lights are usually rated with high lumen output of around 100lm per watt and a lamp life of up to 20,000 hours. The downside to these lights is that they generate a lot of heat. The lamps themselves give off heat as well as the ballasts used to regulate voltage. A good exhaust and air circulation is always essential when growing cannabis but even more so when using HID lighting systems.

 

Things to keep in mind when buying HID lights

• HPS or MH
• Wattage
• Types of Bulbs

 

HPS or MH

There are two main types of HID grow lights, High pressure sodium (HPS) and Metal halide (MH)

High Pressure Sodium (HPS)

HPS lights are the all-round performers of HID lights. They can be used throughout the entire grow. These lights emit predominantly yellow/orange light which is ideal during the flowering stage.   

Metal Halide (MH)

MH lights are just as efficient at growing cannabis as HPS. The light emitted is more blue/white in comparison to HPS but can still be used from seed to harvest. The blue spectrum is ideal for photosynthesis and performs best on vegetative plants. The average life of a MH bulb is 10,000 hours (just over 400 days). This means they will last long enough for small grow operations and can even last form one harvest to the next without any problems. They are also low cost which means they do not require a great investment when the bulb dies out.

For optimal results you can use a MH bulb to vegetate your cannabis plant during the 18-6 hour light cycle. Then switch the bulb out for HPS at the 12/12 light cycle to change to flowering phase. This helps imitate the changing light spectrums that occur in nature when seasons change from spring/summer conditions.

If you can only choose one for your grow cycle, then it is always recommended to go for the HPS bulb as these will do better for your entire grow. 

   

Wattage

HID bulbs come in a range of wattages from as low as 150W to as high as 1000W. The average grower will use bulbs between 400 - 600 watt bulbs. The 1000 watt bulb is quite hot but you can pick this bulb if you can manage the heat it produces.

 

What distance should the light be from the plant?
Bulb	Plant Distance	Recommended Area	Amount of Plants
400W	At least 30cm away from your canopy	Up to 1.1m x 1.1m	6 - 9
600W	At least 45cm away from your canopy	Up to 1.4m x 1.4m	9 -12
1000W	At least 60cm away from your canopy	Up to 1.8m x 1.8m	12 - 16+

 

Types of Bulbs

HPS and MH bulbs come in two different varieties, single-ended and double ended. Although the double-ended bulbs are more expensive, they have shown to be 30% more efficient than single ended bulbs. What this means is that they produce a greater PAR rating for the same watt. 

  

Pros and Cons of HID grow lights

Pros	Cons
Costs less than other high-quality lights	Produces a lot of heat, requires ventilation and exhaust system
Produces great results	Limited lifetime
Easy to setup and operate	Does not plug into a normal socket
	Requires special hood and ballast
	Can significantly increase electricity bill

 

CMH (Ceramic Metal Halide)

The CMH bulb is a variation of the normal Metal halide bulb. These lights use a ceramic core instead of the traditional quartz metal halides use. The ceramic element of these light gives a higher intensity of light that can extremely closely mimic natural sunlight. These types of light contain different types of gas the HPS and MH lights. They also connect much better due to the different thread they come with. This makes these bulbs more secure. The CMH or LEC grow lights hardly create any heat because of the addition of insulation so your plants don’t burn, they also have more UV-A and UV-B in its spectrum, which is very beneficial if you are growing cannabis.

These grow lights are available in a variety of different light spectrums such as growth, flowering and mixed spectrums. 

  

Light-Emitting Diode (LED)

 

LEDs are the newest form of technology but have become increasingly popular amongst growers. Unlike other types of grow lights, LED's do not burn a filament, but instead pass light through semiconductors to create their spectrum. LED grow lights are designed to emit proportions of wavelength colours to which plants respond best.

LED grow lights combine a high number of red and blue light emitting diodes to act as a catalyst for photosynthesis during plants vegetative and flowering stages. Honing in on the proper light wavelengths necessary for plant photosynthesis is one primary reason that LED grow lights are a popular choice. They have the added bonus configurations that include infrared and ultraviolet options, they are power-efficient and run considerably cooler per lumen emitted compared to HID lights.

LED lights can be costly but with their lifespan of +- 50 000 hours, the initial investment can be worth it in the long run.

LED lights provide coverage to only a small space of area so you may want to purchase more than one. They are also less intense when compared to other lights.

 

Things to keep in mind when choosing a LED light

The LED Chip

The semiconductor chip is the LED light's core. Its purpose is to convert electricity to light, but also plays a part in determining the wavelength. It is advisable to look for a light that has a chip of at least 3 watts, otherwise it will not be able to provide your plants with sufficient illumination.

The output

You should always check how many units is the total output. The options go up to 1000W, but you should not settle for anything less than 300W. Keep in mind that the higher output helps compensate for any loss in wattage.

Cooling Aspects

Your lights will be on for most of the day, often up to 18 hours at a time, so you want to make sure they have internal fans that protect the lamp. LED lights run cooler than HPS bulbs, but the heat happens behind the bulb in LEDs and that area needs to be protected. A good quality LED light will have aluminium heat sinks attached to the back exterior or interior which forces heat away from the chips.

The spectrum

Cannabis plants can grow under almost any type of light, but efficient photosynthesis requires different wavelengths and some of the best LED grow lights can provide the full spectrum necessary throughout each growth stage. 

  

Pros and Cons of LED grow lights

Pros	Cons
The most energy efficient grow light	High initial costs
Low heat output
Plugs into standard outlet
Long lifetime

 

    

Fluorescents Lights (CFL, Tube lights)

 

Fluorescent lights are a good option for small grow setups and novice growers. They will not penetrate the canopy with great intensity but are a great option for anyone who is concerned about energy consumption or temperature control. They are also a good option for growers who are working with a confined space or a limited budget. There are two main types of fluorescent grow light, CFL and T5 fluorescent tubes.

  

Compact Fluorescent Lights (CFL)

CFL lights draw the least amount of power and are the cheapest option compared to LED and HID. Many growers choose to use CFL lights during the early stage of sprouting or for developing clones, as during these stages the plant does not require much energy.

CFL Bulbs have a cannabis-friendly light spectrum and come in daylights (6500K) for the vegetation stage and soft white (2700K) for flowering. There are also dual spectrum CFL bulbs available which are divided into half, one side of the blue light spectrum and the other side of the red light spectrum. These are great as only one bulb is needed for the entire grow cycle.

CFL bulbs produce light in all directions so when choosing this option, you will need a wing reflector to capture and reflect the lights rays onto the plant. 

  

T5 fluorescent

T5 grow lights are similar to LEDs and CFLs in that they produce much less heat which means you can hang them much closer to your plants. This grow light also uses less energy and can simply be plugged directly into the wall, unlike the MH/HPS bulb, which requires a ballast and a reflector. With a lower wattage than high intensity systems, these fluorescent grow lights are perfect for germinating seeds, rooting clones and for the first few weeks of the growth period. 

 

Pros and cons of Fluorescent grow lights

Pros	Cons
Inexpensive	Low light output compared to other types of bulbs
Good for small grows	Needs to be close to plants
Widely available	Not meant for large grows
Works in any standard light fixture
Available in various colour temperatures

 

   

Some Final Notes on How to Choose A Grow Light

As you can see there are many factors that go into choosing a grow light. Once you have taken all the different factors into consideration, it is up to you to decide which grow light will best suit you. Keep in mind a cannabis plant will grow under almost any light but the important thing is to remember to provide your cannabis plants with the correct light spectrum for each different growth stage as well as providing enough light so that your plant can grow happy and healthy.

 

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