HID vs. LED – Ideal Grow Lights for Cultivating Cannabis Indoors

Quality, undoubtedly, is one of the most crucial factors when we spend our precious dollars on anything we buy. Likewise, good quality becomes the key concern for producers and they want their crops to flourish. Studies [1] have shown the positive effects that certain lights tend to have on plants grown indoors. Popularly, known as ‘Grow Lights’, these forms of brightness come in various brands and grades. So how to pick the most effective option?

Natural sunlight contains the entire spectrum of light. Like their outdoor counterparts, indoor plants too, require this complete light spectrum to grow. Therefore, it is important to ensure that bulbs that act as replacements for natural sunlight are able to provide a balance between cool and warm lights.

Cannabis plant requires abundant sunshine [2], however, it also emits a powerful odor and can be harmed by pests. This is where grow lights come in handy. They are known to benefit plant growth from the seedling stage itself. Grow lights are popularly categorized as follows,

  1. HID or High-Intensity Discharge Grow Lights – these can be high-pressure sodium (HPS) lights, metal halide (MH) or ceramic metal halide (CMH)
  2. LED or Light Emitting Diode Grow Lights – LEDs come in various types and don’t have separate sub-categories.
  3. Fluorescent Grow Lights – Fluorescent grow lights are more commonly known as, CFLs or Compact Fluorescent Lights. They are also available as fluorescent tubes like the T5 grow lights.

 

As the quality and health of indoor plants depend largely on the light under which they are kept it is important to know which grow light provides higher yield and better quality. While the jury is still out on the perfect solution, we seek to provide an accurate comparison in the use of HID and LED grow lights for the cultivation of cannabis.

Which one is better for Growing Cannabis? HID vs LED Grow Lights

Simple science says that the more light you provide to the plants, the more they will grow. However, light bulbs manufactured using different techniques emit different colorswhen lit. This can have an impact on plant growth as in the vegetation stage, most plants require light with a heavier blue spectrum. In contrast to this, plants in the flowering stage require more red light to flourish. Therefore, it is important to understand the difference in the lights available in the market. While fluorescent grow lights have their own advantages, HIDs and LEDs are the current market leaders.

 

Ceramic Metal Halide[3] (CMH) lights are the most efficient type of HID grow lights as they can last up to eighteen months and also produce more light output as a ratio of electricity watt. For cultivating cannabis, their spectrum of light is fuller and increases the plant’s overall health, yield, and growth. The higher ultraviolet output of HID grow lights also leads to increased production of essential oils. Even though the light spectrum is not as precise as some of the LED grow lights, their penetration levels are much better.

While HID grow lights yield higher outputs as compared to LEDs, they also consume more than double the amount of electricity and produce immense heat. Therefore, an additional setup is required to vent out this heat. Majority of the LED lights available not only run cooler, they usually have an in-built cooling component. They also have a much simpler setup, in comparison.

For smaller harvests, LED grow lights are an economical option as their electricity consumption is lower [4], they require no additional setups and are easy to install. HIDs are more appropriate for growing Cannabis as they help produce higher yields and with HPS grow lights you can have a longer lifespan as well.

Important Differences between HID and LED

Cultivators of plants endlessly debate and speculate as to which type of grow light is more suited for growing crops indoors. HID and LED are two completely different types of grow lights primarily because they work on entirely different technologies. It is akin to comparing apples and oranges; both are fruits and nutritious but, that is where the similarities end. Likewise, both HID and LED are grow lights, but depending on external factors one can prove to be more suited than the other.

At an operational level, the basic differences between HID and LED grow lights are on cost and efficiency [5]. LEDs have always been more expensive as an initial investment and this has kept cultivators at bay. Even though their energy consumption is far lower than most other lights available in the market, making them a cheaper option in a longer duration. HIDs, on the other hand, have a much more complicated setup requirement, but they are more reasonably priced and for this reason, they have been a more popular choice among cannabis growers.

HID lights tend to produce more heat which requires additional cooling setup to be installed, whereas, most LEDs come with an in-built cooling system that prevents them from generating harmful amounts of heat. LED grow packages are also easier to install and don’t require elaborate setups. Most LEDs can be plugged directly into the traditional electrical sockets.

Unlike traditional sources of light, LEDs don’t have a filament that burns out causing frequent breakdowns. HIDs have replaced the filament of a traditional light bulb with a gas capsule but, they still don’t last as long as LEDs. The small semiconductor chip installed in LED grow lights makes them more durable and they can stay lit for thousands of hours. Due to this difference in technology, HID lamps don’t provide full light instantly and can take up to 15-20 seconds to warm up.

HID grow lights, like HPS, produce a great amount of light which is ideal for the flowering stage. The color spectrum of MD lights makes them ideal for the vegetation stage. A combination of these two can provide the best possible yield, however, their electricity consumption is much greater than LEDs leading to an increased cost of operation.

LEDs as grow lights have advanced considerably in the recent few years whereas, HIDs have been a popular choice for a much longer time. Even though LEDs are catching up, HIDs like HPS tend to produce higher yields vis-a-vis the amount of energy consumed. HIDs come in a variety of forms and different types can be deployed to maximize benefits at different stages of the plant’s growth cycle. Combining LEDs with certain types of HID grow lights, like HPS or MH, can lead to higher yields and improve the overall quality of produce.

It is important to consider all factors while selecting grow lights [6]. Every indoor grow room is different, therefore, there is no single ideal formula that can be applied for choosing grow lights. Size of the room and temperatures are just as important to be considered while buying grow lights as the intensity and life span of the light itself.

What are HID Grow Lights?

HID, or high-intensity discharge lamps, have an in-built arc that passes between a pair of electrodes in a highly pressurized tube. This causes multiple metallic substances to vaporize releasing tremendous amounts of light. The electricity initially enters through a ballast in the component containing a fixed HID lamp. Starter inside this ballast gives a strong jolt of electricity that helps ignite the bulb inside the HID light. The electricity that enters from the base of the HID lamp flows into the arc tube which is a glass envelope containing metallic salts and gas. The gas assists in the initial ignition of the light. This gas heats up and helps in vaporizing the metallic salts. This process leads to chemical combustion and produces artificial light.

 

The light created is sufficiently bright and powerful and can light up from a long distance. For this reason, HIDs are a popular choice when lighting up stadiums or gas stations. As grow lights HIDs are still the most popular option among horticulturists. Unlike fluorescents, High-Intensity Discharge lamps come with a much higher lumen-per-watt efficiency.

 

Popular types of HID Grow Lights

  1. HPS (High-Pressure Sodium) Lights – High-pressure sodium lights are heavier in the red area of the light spectrum. They are, therefore, considered ideal for fruiting and blooming stages of Cannabis’s growth cycle. HIDs come in multiple sizes ranging from 150W to 1000W. The redder hue produced by these lamps resembles the light emitted by the autumn sunset. This tone also increases the flower-to-leaf ratio in fruiting and flowering plants. HPS grow lights are used to artificially increase the natural light for plants replicating the summer. HPS lights are mostly used when natural light hours are lesser or when the plants are grown indoors.
  2. MH (Metal Halide) – MH, or Metal Halide lights, emit light which is of a bluish tone. Therefore, it is one of the most popular types of grow light that is used for vegetative and propagation of the plant. These lights imitate the hues of spring and summer making them an ideal option that promotes short intermodal growth. MH lights have been available in the market for a few decades now and apart from growing lush greens, they are also used in street lighting and as car lamps.
  3. CMH (Ceramic Metal Halide) – Although similar, Metal Halide and Ceramic Metal Halide are not the same. CMH lights are built around a ceramic arc tube, whereas, MH lights use quartz arc tube. CMH grow lights also provide a better spectrum of light than the MH lights. Apart from higher white and red light outputs CMH lights also produce more PAR light. They are more durable than both MH and HPS grow lights and have a longer lifespan. These bulbs provide a broad and wide light spectrum. Like the sun, CMH grow lights provide Ultraviolets (UVs).

Key Advantages of HID Grow Lights

HID grow lights are a popular choice for growing Cannabis plants indoors. The excellent yields [7] and ideal value provided by both HPS, CMH and MH type of HID grow lights make them a highly recommended alternative to natural sunlight.

HPS lights provide a yellow-orange-red light that is ideal for increasing yields in the flowering and fruiting stage. However, the results are lesser when given in the vegetation stage. MH bulbs, on the other hand, shine a bluer hue that strengthens plant’s growth during vegetation but offers lower yields during the flowering stage.

Following are some of the important benefits of using HID grow lights,

  1. Higher Yields – HID grow lights like HPS, MH, and CMH provide the best light spectrum that helps in higher yields. A light source is a key factor when gardening indoors. With a poor light source, the end result can be rather disappointing.
  2. Lower Cost – HIDs are some of the cheapest grow lights available in the market. They are also cheaper in terms of output per wattage cost making them energy efficient. HPS lamps are the most efficient type of HID grow lights.
  3. Longer Lifespan – this specifically applies to Ceramic Metal Halide lights. They have a much longer lifespan in comparison to other HID grow lights.
  4. Simpler to use – Most HID lamps can be dimmed making them more customizable. Also, if the grower is using a digital ballast then all types of HIDs can be used without any change to the ballast.
  5. Convenient to repair – As HID lights are made up of several different components, it is easier to fix them. Just replace the broken component rather than the entire light. This practical advantage is very useful as a malfunctioning light can prove to be disastrous during the plant’s growth stage. Also, replacement components and lamps are widely available for HID grow lights.
  6. Reliable and Consistent – As indoor sources of light for plants, HID grow lights have been in use for over three decades now. Veteran cultivators of cannabis maintain that HID grow lights provide higher yields and improve the overall quality of the produce. Unlike LEDs, HID grow lights have proven to be more consistent across manufacturers and models, in terms of both quality and performance.
  7. Unlike LEDs, HPS grow light that is mounted, say 4 feet above the plant canopy can provide a much wider angle of light. In other words, the crop gets more light directly from above and from lights installed in the next few rows as well.
  8. HID grow lights are considered the brightest and usually the most effective lights. High-Pressure Sodium HIDs emit the spectrum of light which stimulates the plant’s hormones and increases flowering or budding, depending on the plant growth cycle.

To achieve optimum performance in HIDs, it is recommended to combine HPS grow lights with MH light bulbs. In this type of setup, Metal Hilde acts as the primary source of light and HPS lamps are used to enhance the yield during the flowering stage of the growth cycle.

Key Disadvantages of HID Grow Lights

  1. High heat generation – HID grow lights, especially 600W and above produce large amounts of heat which can prove to be a fire hazard in confined indoor growth spaces. This property of HID grow lights can overheat the area, therefore, requires additional expense to make appropriate cooling provisions.
  2. Additional Setup – Due to overheating HID grow lights require additional setup for cooling the area. Growers need to install exhausts and provision for appropriate vents. Further, HIDs cannot be directly connected to the standard light sockets. They require a specially designed hood and a ballast.
  3. HIDs require frequent bulb changes in comparison to LED grow lights. This increases operational costs in the long run.
  4. According to recent studies [8], HIDs produce substantial amounts of infrared radiation that is completely wasted energy which increases the temperature of the surroundings.
  5. HID grow lights are omnidirectional, that is, they produce light in the entire 360-degree area. Due to this feature, HIDs require reflection and refraction of light. This increases the unit cost as more accessory components are required in the fixture itself. It also reduces the intensity of light that it bounces off the surface of the reflector.
  6. Uneven Light Spectrum – Most HID grow lights produce an excess of green and yellow lights which translates into a substantial amount of photon energy that is wasted.
  7. HID lights are considered as inefficient below 400W [9] and it is often more advantageous to replace them with cooler LED or fluorescent lights.
  8. On the other hand, a 1000W or above intensity HID grow light is generally too strong and powerful for home growers.

 

HIDs have held a higher PAR (Photosynthetically Active Radiation) leading to higher yields. However, newer and improved LEDs are not just matching, but also, surpassing the per yield watt figures generated by HIDs.

What are LED Grow Lights?

LEDs, or Light Emitting Diodes, grow lights are lights which include multiple individual diodes. The primary structure of LED grow lights is made up of a small semiconductor chip that is covered by a capsule and a junction which allows the flow of electric current in the form of multiple electrons. This unidirectional flow of electrons emits a different type of photon. This is how photon emitting LEDs function and produce varying light colors and radiations. In spite of all the light emitted, thermal energy is produced in bare minimum quantities.

LEDs do not use lead, mercury, filament or gas to generate light. As it has no fragile glass bulb components, it is less prone to failure due to moving parts.  They simply create their light spectrum by passing it through semiconductors. LED grow lights don’t require a separate ballast as well and unlike HIDs, can be plugged into a standard socket.

LEDs have become a popular choice of grow lights for indoor cultivation also because of their ability to provide a very specifically targeted spectrum of light. While HIDs produce around 40% PAR efficiency, LED grow lights are capable of delivering up to 80-100%. These lights can adjust their spectral output which allows the emitted wavelengths to ideally match with the photoreceptors in the plant. This increases efficiency as no energy is wasted on producing light that can’t be used by the plant.

Traditional LED grow lights use combinations of red and blue LEDs as plants perform the process of photosynthesis more effectively in these color areas of the light spectrum. Newer studies have shown that a full spectrum of light is required for optimum growth of plants. While the claims are yet to be researched, the newer versions of LED grow lights can emanate a fuller spectrum of light.

It is always recommended to opt for better quality LED grow lights as they may be more expensive, but their operational cost and the impact on electricity consumption is much lower.

With more research and development, LED grow lights have become affordable and more reasonably priced. However, it is their long glow span that has made them popular with indoor plant cultivators. LED grow lights have an average lifespan of 50,000 hours [10].

It is extremely important to follow instructions while installing LED grow lights as they can damage plants if kept too close. While most LEDs work best at a distance of 18-24 inches from the plant, it is recommended to check with the manufacturer. Apart from distance, factors like the size of the bulb, the shape of the lens and angle of the light directed by the lamp should be considered before installation.

Even though LED grow lights don’t generate as much heat as their HID counterparts, they can still cause light damage or ‘light burn’ [11]. This is akin to skiers getting sunburn from the sunlight that is reflected on the snow, even though the temperatures are cold. As light is food for plants, excessively bright light can cause them to harm like discoloration or reduction in their potency.

Key Advantages of LED Grow light

Although the first LEDs were marketed in the late 1960s, they were lacking in technology. Over the decades, slow yet steady improvements to this technology have made it a front runner for indoor use as plant grow lights. Following are some of the key advantages of utilizing these lights vis-a-vis other grow lights,

  1. Energy efficient – LEDs have unique capabilities of targeting a very specific area of the light spectrum. LEDs are capable of maximizing their PAR efficiency to nearly 100% [12]. As they target plant preferred wavelengths LED grow lights don’t waste electricity by producing light which remains unused. In other words, they produce more light per watt when compared to HIDs and fluorescents reducing your overall electricity bill.
  2. Run cooler temperatures – LED grow lights produce much lower levels of thermal energy in comparison to HIDs. As the cost to cool the indoor grow area can run into substantial operational cost, the cool running of LED grow lights becomes an important advantage when compared with their HID counterparts. LEDs have in-built cooling that reduces the heat emanated. As they generate lower heat around plants, there is a lesser need to water the plants.
  3. Cheaper – even though the initial investment is more as compared to fluorescent and HID grow lights, LEDs have a much longer lifespan that makes them a cheaper option in the longer run. They can run for nearly 11 years in full operation or for as many as 22 years at 50% operation. Also, as their lamps are much cooler, LED grow lights can be used for cultivation in smaller areas thus, lowering the cost of investment.
  4. Easy to install – Most LEDs can be directly plugged into standard electrical outlets and don’t require separate ballasts. Unlike HIDs they don’t come with complicated setups and can easily be installed in an indoor cultivation environment. LEDs can also function on a low-voltage power supply.
  5. Wide range of the color spectrum – It is very important to generate the right color spectrum of light, else the entire investment can prove wasteful. Sunlight contains all the colors in the color spectrum. Most LEDs come with blue or red lights and are available in cheaper options. However, there are more expensive LED grow light options available that mix different colored bulbs and offer white light resembling the sunlight. These white LEDs are also lower in intensity as compared to HID grow lights.
  6. Flexible design – LED grow lights have a more flexible design and technology in comparison to other lights available in the market. Apart from ceiling lights, they can also be used as inter-lighting designs between plants and as vertical multilayer systems. These deployments are more energy efficient as plants receive more light leading to better growth stimulation.
  7. Environment-Friendly – Unlike fluorescent bulbs, LED grow lights don’t produce any harmful or toxic chemicals like mercury, making them more eco-friendly. They are also recyclable [13] and can help you reduce your carbon footprint.
  8. Slower Lumen Depreciation – Lumen depreciation in newer LEDs occurs over a much longer time than their HID counterparts.

Key Disadvantages of LED Grow Lights

LED grow lights have traveled a long distance over the last decade or so and are quickly catching up with HID sources on technology and usability. In spite of the advancements made in LED technology, they still have a few drawbacks. Following list seeks to cover some of the major disadvantages of using LED grow lights for indoor cannabis cultivation.

  1. Higher Cost of Investment – The cost of LED grow lights is also one of its major disadvantages. Even though they prove to be a more cost-effective solution in the longer run, the initial high cost of investment in LEDs can deter many indoor cultivators.
  2. Emit less light than HIDs – In an effort to reduce costs, certain lower grade LEDs emit lesser light that may not be as beneficial for plant growth. It is very important to research this aspect before making any purchases. The selected LED should at least provide 2.0 micromoles per watt.
  3. Correct Placement – It is crucial to place LEDs at an optimum distance from the plant. Too far and the plant may not receive enough nutrition and placing them too close can cause a ‘light burn’ in plants.
  4. Ageing – LED diodes tend to change color[14] as they grow older and may fail to produce the correct quality of light required for a healthy yield. However, this problem occurs mostly in the cheaper quality of LED chips.
  5. LED grow lights are sensitive to extreme temperatures, therefore, it is imperative to maintain optimum temperatures. High temperatures can damage the LED module.
  6. As light from most LEDs is direct, there is always a chance that it may not cover the entire plant sufficiently.
  7. Long exposure to LED’s blue and other color lights can cause blindness in humans, therefore, it is not recommended to look directly at these grow lights.

 

Source:

  1. https://advancedledlights.com/blog/technology/nasa-research-optimum-light-wavelengths-plant-growth/
  2. https://alliedscientificpro.com/blog/welcome-to-our-blog-1/post/lighting-in-relation-to-growing-cannabis-38
  3. https://growlightinfo.com/best-ceramic-metal-halide-chm-grow-light/
  4. https://www.growlightsource.com/blog/what-are-the-benefits-of-grow-lights-and-how-do-they-compare/
  5. https://newsspaceflight.com/2018-2023-global-grow-lights-market-share-cagr-status-market-growth-trends-analysis-and-forecast-360-market-updates/
  6. https://www.urbanvine.co/blog/11-core-guidelines-urban-farmers-must-know-before-buying-grow-lights
  7. https://productiongrower.com/blogs/how-to-grow-weed/selecting-grow-lights
  8. https://hightimes.com/grow/switching-led-heres-what-you-need-know/
  9. https://www.bigbudsguide.com/led-grow-lights-vs-hid-grow-lights/
  10. https://www.electronicsweekly.com/blogs/led-luminaries/led-life-expectancy-2009-02/
  11. https://growlightinfo.com/advantages-and-disadvantages-of-led-grow-lights/
  12. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3949401/
  13. https://businessrecycling.com.au/recycle/led-lights
  14. http://www.ledbenchmark.com/faq/Color-Shift.html