Lighting & Cannabis

Written by: Madelynn Gevaert / Jan 19th 2023

As a new grower, you might be wondering which lighting set-up is perfect for you and your grow. This guide will help to explain the differences between LED, Fluorescent, HPS, and MH(HID) to help you choose which is best for your indoor grow.

LED (Light Emitting Diodes)

What are LED Grow Lights?

LED stands for light-emitting diodes. LED lights have been becoming increasingly popular for the modern indoor garden, and in greenhouses. The energy-efficient bulbs use up to 40% less energy, LED grow lights are by far the most energy and cost efficient bulbs on the market, all while having a much longer lifespan as well.

Pros and Cons of Growing with LED's

Pros	Cons
Energy-efficient, using up to 40% less energy.	LED's are more expensive upfront. However, they do not need to be replaced as often.
Lasts longer than most lighting options, with anywhere from 50,000 to 100,000 hours lifespan.	Harsh on the eyes. LED lights can cause LED radiation and cause irreversible damage to the retina if PPE is not worn.
Being more energy efficient, they also produce much less heat than something like an HPS set up.	Not enough heat output. If you aren't running a heater with this during colder seasons, your plants will not get enough warmth.

How do LED Grow Lights Work?

LED (Light Emitting Diode) grow lights are made of many LED chips that operate as diodes, which emit light at a specific wavelength and are able to produce different spectrums such as UV, blue and red are the most commonly used. Blue coloured LED lights are typically used for seedling and vegetative growth, whereas red coloured LED lights are better suited for use while plants are flowering or budding.

Fluorescent What are Fluorescent Lights? Fluorescent Lights are typically referred to as T5. These lights produce very small amounts of heat, making them good for smaller areas. Having a lower-intensity light output, these fixtures are best for small plants such as seedlings, clones, herbs and other things like microgreens and houseplants etc. These are not the best suited light for a primary light source for larger plants.

Pros and Cons of Growing With Fluorescent

Pros	Cons
Low heat levels, safer to place closer to plants.	Not a good option for plants that are in the flowering stage, more specifically for seedlings and clones.
Generally more inexpensive, you don't need to replace the whole fixture if light is burnt out, only the bulb, compared to LED.	Not a good option for plants that are in the vegetative state, more specifically for seedlings and clones.
The spectrum resembles full daylight like the sun and covers more area than most kinds of grow lights.	Lifespan can be shortened significantly if being turned on and off too often, better to set with a timer.

How do Fluorescent Grow Lights Work?

Fluorescent grow lights work by utilizing an electric current to heat up the gas (argon - used to stop the oxygen in the light bulbs from corroding the hot tungsten filament). Once the gas has been heated up, ultraviolet light is emitted.

MH (Metal Halide)

What are MH Grow Lights?

MH or also known as Metal Halide is a type of HID are widely used in the cannabis industry. Providing efficient light and a deep canopy penetration MH lighting encourages faster growth resulting in strong plants and greener foliage. This kind of light is most often used during the vegetative stage of growth, due to the range of blue light that is offered.

Pros and Cons of Growing with MH

Pros	Cons
Efficient, these lights are more efficient and cost-effective than other HID lights.	Typically a higher price point, bulbs can be costly to replace.
MH bulbs offer a great penetration and offer a vast light supply compared to other lights.	High heat output, this could be an issue in smaller tents that don't have proper ventilation.
Lifespan, MH bulbs have a long lifespan, with some models lasting up to 10,000 hours.	Can be used during flowering, however it will not provide as much red light as needed.

How Do MH Grow Lights Work?

MH lights, like all HID (High Intensity Discharge) are a gas discharge lamp. This works as a current of electricity runs through the lamp causing mercury to heat up, turning into a gas which then in-turn produces light.

HPS (High Pressure Sodium)

What are HPS Grow Lights?

HPS (High Pressure Sodium) is another very common type of lighting used for growing, most commonly used during the flowering stage. These lights imitate the sun to a T, sometimes it even does better than natural sunlight, promoting flower and root growth. These lights have a great light output and spectrum and are able to grow a larger range of plants. That being said, these lights also output a great deal of heat, so it is important to have proper ventilation to avoid overheating and damage to the plants.

Pros And Cons Of Growing With HPS

Pros	​Cons
Does exceptionally well during the flowering stage, the spectrum is made of red, orange and yellow wavelengths.	Very high heat output, if the light isn't far enough from the plants and the area doesn't have proper ventilation, you will damage your plants.
The dimmable ballast - a nice feature to be able to dim down your light and have more control over the output.	Bulbs don't last as long - HPS bulbs tend to last from 2,500 hours to 5,000 hours.
Affordable - HPS bulbs and fixtures tend to be relatively cheap compared to other light alternatives.	Costly on hydro bills - these types of lights require more energy to run, compared to an LED.

How do HPS Grow Lights Work?

HPS (High Pressure Sodium) lights are powered like all other HID (High Intensity Discharge) where an electric current is passed through a tube filled with either sodium, mercury or xenon, this current will heat up these chemicals, making them into a gas which then produces light.

Thanks for Reading!

We hope this article has made your decision on choosing the right light for you and your grow.