How to choose the right lighting solution for medical cannabis cultivation?

By John | Dec. 24, 2021


According to the BDSA Reports released on March 12, 2021, the Global cannabis sales (including the medical cannabis and recreational cannabis) hit record $21.3 billion in 2020, rising by $784 million compared with 2019, growth of 48% over 2019’s $14.4 billion. Especially, the US cannabis in 2020 was a breakout year, Legal cannabis sales in US market reached nearly $17.5 billion in 2020, accounting for 82.15% of the global sales. According to the average growth rate in the past few years, global cannabis sales are expected to exceed 30 billion in 2021.


The global medical cannabis market reached a value of US$ 7.8 Billion in 2020, and expect a market grow at a gear of 15.3% in the coming few years.






How to choose HPS VS LED during the cannabis cultivation which were frequently asked by many growers. I am comparing LED to HPS for the cannabis operation. All most the growers use the HPS or MH lamp before due to the immature technology on LED. In the passed years, HPS consisitently got good yield with its highest efficacy rating, up to 1.9umol/j. However,  the PPE of LED can reaching 3.0umol/j currently while HPS efficiency is fixed. After many years’ development, the LED deliver superior lighting performance in meeting the cannabis plants and the efficiency of LEDs still continue to increase in future.





Equivalent wattage



PAR efficacy (PPE)

Less than 1.9umol/j

Up to 2.8umol/j


Less than 2 year  (Replaced every year)

5 years at least  (No need to replace with 5 years)


Can not be changed

Full spectrum, can be customized for different cultivation stages

Energy saving

more electricity costs

Saving up to 32%


Huge heat

Little heat

Control system


Can be controlled via trolmaster controller or GK controller


How to choose the right led grow light?


Here are 6 important factors to consider when choosing the ideal led grow lights.


1. Light output


Cannabis belongs to an extremely light-hungry plant once it starts to bloom. It requires low PPFD value 100umol/s.m2 at the seed germination stage. However, as it starts to grow and thrive, the demands for PPFD value increased to 800-1400umol/s.m2 at the later flowering stage. Thus you need to choose the led grow light with enough PPFD value to meet your single cultivation stage or full cycle cultivation stages.

For the indoor medical marijuana cultivation, we all know that the Cannabis growth is divided mainly in seed germination, seedling, vegetative, and flowering stages. But many growers may skip the germinating and seedling periods, and start the cultivation from Vegetative to Flowering directly. Each stage has its own environmental and nutritional needs, even different photo periods.





Date: 3-10 days

Suggested PPFD value: around 100umol/s.m2

Light/Photo period: 18 hours on and 6 hours off

Spectrum: more blue light preferred

Mounting Height: 14-36 inches above the plant canopy



Date: 2-3 weeks

Suggested PPFD value: 100-300umol/s.m2

Light/Photo period: 18 hours on and 6 hours off

Spectrum: more blue light preferred

Mounting Height: 24-36 inches above the plant canopy


Vegetative stage

Date: 3-8 weeks

Suggested PPFD value: 400-800umol/s.m2

Light/Photo period: 18 hours on and 6 hours off

Spectrum: more blue light preferred

Mounting Height: 12-24 inches above the plant canopy


Our GK LED grow light model G10-320W and G10-500W led grow light were specially designed for the Cannabis vegetative stage. Most cannabis growers agreed that a light source with a good proportion of blue light benefits more at the vegetative cultivation stage. Our GV2 spectrum is designed with high proportion of blue light, aiming to produce a stockier plants, and reduce internode stretching.  

Besides, G10-320W is made of 6 bars, they provide a larger coverage area and uniform lighting, optimize their grow space for the maximum yield. With knob dimmer fixed on the fixture, the wattage can be adjusted from 100% to 0%, these two models can be also used for the seeding germination and seeding stage.




Flowering stage  (also called Bloom stage)

Date: 8-10 weeks

Suggested PPFD value: 800-1400umol/s.m2

Light/Photo period: 12 hours on and 12 hours off

Spectrum: more blue light preferred

Mounting Height: 16-36 inches above the plant canopy


Our models G10-680W, G10-720W and G10-960W are suggested for the full cycle cultivation stages. Especially, our G10-960W with Photon Flux up to 2500umol/s is more suggested for the professional commercial scale growers with CO2 at the cannabis flowering stage.





Different colors have different purposes during the cannabis growth. The ideal full spectrum for cannabis depends on the wavelength among 400nm-700nm and the wavelength outside of the 400-700nm range.  

Blue light (400-500nm): it can benefit nutritional levels and coloring, making sure the cannabis plants with more thicker and darker leaves.

Green light(500-600nm): green is absorbed and used for photosynthesis and penetrates leaf layers effectively.

Red light(600-700nm) and Far red: a higher red to far-red ratio can help with leaf size and flowering.

According to the functions of different wavelength, cannabis vegetative stage should come with more blue light, less red light, while more red light, less blue light for the flowering stage.




Cost is a top priority with commercial medical cannabis growers alike. It includes the initial cost and operation cost, for example, initial cost includes the electrical led grow light, air conditioning , labor and accessories, while operation cost includes electricity, maintenance and others.

LED grow light is more expensive than the traditional HPS/MH lamps. However, the lift span for the led grow light is very long, can be used for 5 years at least, that means, the average annual cost is low in 5 years.

When choosing the led grow light, the power determines how much electricity will be used in the future.



Air conditioning is another expense you’ll need to manage as you remove light-generated heat during your growing space. Lower wattage means less heat and less costs. Large wattage means more heat and more costs. You need to get the right wattage to heat your house (as measured in BTUs).  watts to BTU/hr is 1 watt to 3.41 BTU/h.

However, there is one solution that can removes LED driver heat from grow space, that is, using our GK GCP series central power solution system, each cabinet can handle 240pcs 600W led grow light.


5.Space grow area

For the hobby grower, the grow tents were more suggested for cannabis growing. Due to the small growing space, the G10-480W with 2ft by 4ft size and G10-680W with 4ft by 4ft size are more recommended.

Another most two popular cannabis planting sites will be indoor and greenhouse. For the indoor cannabis cultivation, the led grow light should provide enough light output as there is no any sunlight. Usually 600W-720W led grow light are enough for the cannabis growth, but some professional growers prefer large one, such as 960W, even 1200W.

But the lighting fixture for the greenhouse cannabis cultivation is total different. The main lighting source in the greenhouse is the natural daylight. and the day length or season will impact the actual DLI and lighting time. Therefore supplemental lighting is widely used to increase cannabis yield in greenhouse. For example, our GK G12 series 1000W led top lighting, which is specially designed as greenhouse lighting.


6.Vendor background

We all know that led grow lights benefit for cannabis plant growth. However, it doesn’t mean any type led grow light on the market will help your cannabis cultivation. There may still some factors, for example, factory size; R&D strength; the spectrum used correct or not; the quality is good or poor; warranty in 1 year, 3 year, 5 year or longer; how they provide the after service; a new starter or a rich experience vendor, etc.  All these need to be considered before decision.


GK focus on horticulture lighting with an independent R&D team and sales team from 2017. Till now, GKhorti has become a one-stop LED lighting solutions manufacturer for indoor plants and greenhouse projects, including the LED grow lights for indoor cultivations, LED top lighting solutions, and LED interlighting module for greenhouse projects, the most advanced medical central power solution, vertical grow rack systems, etc.






In order to grow a healthier cannabis plants and achieve a higher yield, it is crucial to offer your cannabis plants with the proper intensity of light. Although the growth of cannabis plants are affected by many factors, led grow light is one of the most important influencing factors.



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