One of the most effective tools in today’s commercial growing are grow lights. These specialized light fixtures are engineered to replicate the the suns light spectrum and intensity. This aids the plants growth and production.

So, what’s the underlying engineering behind grow lights? Grow lights are designed to produce specific light spectrums that mimic the sun. These spectrums play a critical role in photosynthesis. For growers who are focused on maximizing production or vegetative growth, the choice of light spectrum—red for fruiting and flowering, blue for vegetation—can significantly impact your yield. Additionally, full spectrum light sources produce both blue and red spectrums with one light, which completely simplifies the growing logistics.

What are Grow Lights?

Grow lights are specialized light fixtures engineered for the agriculture industry. They are typically used for indoor grow operations where grow conditions can be controlled and optimized. Unlike standard commercial and industrial lighting, grow lights are tuned to emit specific light wavelengths that mimic the suns light spectrum. They are essential for any operation interested in year-round growing.

Grow lights are available using different light technologies. Older technologies like fluorescent and high pressure sodium were common place until LED grow lights were created. Today, LED lights lead the way as they do in most lighting applications outside of grow lighting, offering many of the benefits that grow lights offer without the high energy consumption or heat production.


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Brief History and Evolution

Grow lights started in the early 20th century when researchers first started exploring the impact of artificial light on plant growth. Initial systems were primarily incandescent lamp sources. These lights offered a very narrow light spectrum and were very energy-inefficient.

In the 50s and 60s, fluorescent lights were introduced for commercial lighting. Fluorescent lights offered a broader spectrum when compared to incandescent lighting. However, they lacked the needed lumen output and light intensity.

The real game-changer came with High-Intensity Discharge (HID) lights. HIDs offered significantly higher lumen output and intensity. They also offered a more balanced light spectrum. They became the chosen light source for commercial growing facilities and replaced fluorescent lighting.

With the introduction of LED technology, it was engineered and developed to serve commercial growers. LEDs are energy-efficient and highly customizable. This allowed growers to custom-select power, intensity, and light spectrums for their needs. LEDs are known for longevity and low heat output. They are a good choice for indoor climate-controlled agricultural facilities.

Today, the grow light industry continues to innovate. They continue to focus on sustainability, energy efficiency, and spectrum optimization.

The Science Behind Grow Lights: What is Photosynthesis?

It is the process that makes plants grow and how plants and trees turn sunlight into glucose. Glucose is food for the plant and is used in growth, flowering, producing fruit, and fighting off diseases.

The process starts when chlorophyll, the pigment responsible for a plant’s green color, absorbs light particles. Light excites the electrons in chlorophyll and starts a process that converts carbon dioxide and water into glucose and oxygen. Glucose is used as food and oxygen is released into the atmosphere.

Understanding photosynthesis is pivotal for commercial growing operations. Engineers manipulate artificial light to affect the rate of photosynthesis. The higher they can affect photosynthesis the higher the plant yield.

How Does Sunlight Support Photosynthesis?

The sun serves as the ultimate light source for plants. Sunlight includes a balance of blue, red, and far-red light. Blue light aids in vegetative growth. Red light stimulates flowering and fruit production. Far-red light plays a role in seed germination and leaf expansion.

Sunlight’s varying intensity throughout the day as well as changing angles of incidence during different seasons contribute to a plant’s life cycle. It’s this dynamic nature of sunlight that makes it effective in the photosynthesis process.

Natural sunlight has its drawbacks. It’s not reliable and predictable. Factors like weather and seasonal changes can result in inconsistent light conditions. This is why commercial growers choose grow lights. It helps growers create consistent and optimal photosynthesis rates. Grow lights can effectively replicate the natural sunlight process when used with light rail kits. This automated movement on a light rail reduces hot spots and will increase yield.

What is the Light Spectrum?

“Light spectrum” refers to the range of electromagnetic wavelengths that are visible and invisible ( to the human eye ). It’s a continuum that starts from shorter gamma rays, then X-rays, ultraviolet light, visible light and ending with the longer wavelengths like infrared, microwaves, and radio waves. For agricultural purposes, we are only concerned with the visible light spectrum, which ranges from 380 to 750 nanometers.

The visible light spectrum can be further divided into various colors. These are violet, blue, green, yellow, orange, and red. Each with its unique wavelength range. These colors play specific roles in growth and development of the plant. Blue light (400 to 500 nanometers) is crucial for promoting vegetative growth. Red light (600 to 700 nanometers) encourages flowering and fruit production.

How Do Grow Lights Differ from Natural Light?

Comparison of Natural Light and Artificial Light Sources

When it comes to plant growth and development, both natural and artificial light sources have their distinct advantages and limitations. Let’s break it down:

Natural Light


Full Spectrum: Sunlight provides a balanced, full-spectrum light that supports all stages of plant growth.

Free Source: Sunlight doesn’t come with an operating cost, making it economical in that sense.

Seasonal Cues: The sun’s changing intensity and angle throughout the year can naturally trigger plant behaviors like flowering.


Inconsistency: Weather conditions, time of day, and geographical location can make sunlight unreliable.

Limited Control: It’s challenging to control the intensity and duration of natural light exposure.

Space Requirement: Outdoor growing requires more land, which may not be feasible for all commercial operations.

Artificial Light (Grow Lights)


Controlled Environment: Grow lights offer precise control over light intensity, spectrum, and duration, allowing for optimized growing conditions.

Year-Round Cultivation: Indoor farming with grow lights eliminates the limitations of seasons, enabling continuous production.

Space-Efficiency: Artificial lighting allows for vertical farming and other space-saving techniques.


Energy Costs: Operating grow lights can consume a significant amount of electricity, affecting operational costs.

Initial Investment: High-quality grow light systems can be expensive to purchase and install.

Learning Curve: Understanding the different types of grow lights and their optimal settings can require a bit of expertise.

Types of Grow Lights

LED Grow Lights

LED (Light Emitting Diodes) grow lights utilize semiconductor technology to convert electrical energy into light and emit specific wavelengths optimal for plant growth. Unlike High-Intensity Discharge (HID) or fluorescent lights, LEDs are energy efficient, customizable, and long-lasting.

Advantages of LED Grow Lights

Energy Efficiency: One of the most compelling advantages of LEDs is their energy efficiency. They consume significantly less electricity compared to HID or fluorescent lights.

Longevity: LED grow lights have a longer lifespan, often exceeding 50,000 hours, reducing the need for frequent replacements.

Customization: LEDs can be fine-tuned to emit specific wavelengths of light, allowing growers to cater to the unique needs of various crops during different growth stages.

Low Heat Output: Unlike other lighting solutions that can generate a lot of heat, LED lights run cooler, minimizing the risk of plant damage and reducing the need for additional cooling systems.

Space Efficiency: Due to their compact design and directional light emission, LED grow lights are ideal for vertical farming and other space-saving growing techniques.

Disadvantages of LED Grow Lights

Higher Initial Cost: The upfront cost of high-quality LED grow light systems can be steep, making them a significant initial investment. However, this cost is quickly recovered by the energy savings and reduced HVAC load

Technology Learning Curve: The customizable nature of LEDs means that growers need to understand the light spectrum and intensity needs of their crops to optimize settings, which may require specialized knowledge.

HID (High-Intensity Discharge) Lights

High-Intensity Discharge (HID), like metal halide lights and high pressure sodium grow lights have been a staple in the commercial agricultural sector for decades. These lights function by passing electrical current between two electrodes. These ignite a gas-filled chamber inside the bulb and emits a high-intensity light beneficial for plant growth. The two most common types of HID lights are Metal Halide (MH) and High-Pressure Sodium (HPS), each offering different light spectra suitable for various stages of plant growth.

Advantages of HID Grow Lights

High Intensity: HID lights are renowned for their high light output, making them ideal for crops requiring strong illumination for optimal growth.

Broad Spectrum: Both MH and HPS lights offer a relatively wide range of wavelengths, catering to the needs of different growth stages in plants.

Proven Track Record: HIDs have been used in commercial growing for a long time, offering growers a tried-and-true method for indoor cultivation.

Cost-Effectiveness: While not as energy-efficient as LEDs, HID lights are usually less expensive to purchase initially, making them an attractive option for those on a tighter budget.

Disadvantages of HID Grow Lights

High Energy Consumption: One of the major drawbacks of HID lighting is its higher energy consumption compared to LED lights, which can lead to elevated operational costs.

Heat Emission: HID lights produce a substantial amount of heat, necessitating additional cooling systems to prevent plant stress or damage.

Bulb Replacement: HID bulbs have a shorter lifespan compared to LEDs, requiring more frequent replacements and adding to long-term costs.

Bulkiness: These lights are generally larger and require external ballasts, making them less suitable for space-saving growing methods like vertical farming.

Fluorescent Grow Lights

Fluorescent grow lights were once a popular choice for indoor plant growing. Fluorescent lights function by passing an electric current through a tube containing argon gas and a small amount of mercury vapor. This produces ultraviolet light which excites the fluorescent phosphor coating on the inside of the tube. This produces a visible light.

Advantages of Fluorescent Grow Lights

Low Heat Output: One of the biggest selling points for fluorescent lights is their low heat emission, reducing the risk of plant heat stress and the need for additional cooling systems.

Cost-Effective: Fluorescent lights are generally cheaper than both HID and LED lights in terms of initial setup costs, making them an economical choice for small to medium-scale operations.

Broad Spectrum: These lights provide a balanced spectrum, adequate for seedlings and plants at the vegetative stage.

Ease of Use: Fluorescent lights are user-friendly, requiring no special ballasts and being compatible with standard electrical outlets.

Disadvantages of Fluorescent Grow Lights

Limited Intensity: Fluorescent lights are less intense compared to HID and LED options, making them less effective for plants that require high levels of light.

Energy Inefficiency: While they may be cheaper initially, fluorescent lights are less energy-efficient in the long run, potentially raising operational costs.

Shorter Lifespan: The lifespan of a fluorescent bulb is generally shorter than that of LEDs, requiring more frequent replacements.

Limited Scalability: Due to their lower light intensity and shorter range, fluorescent lights are less suitable for large-scale commercial operations, particularly those requiring high light intensities for optimum crop yield.

Dwayne Kula

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About the Author

Dwayne Kula is President of LED Lighting Supply. On any given day, Dwayne is writing content for the site and helps manage the marketing initiatives that are on-going. He has a Software Engineering degree and still dabbles in writing software for the company as needed. When not working, he enjoys spending time with his family, working out, playing the occasional game of golf and exploring New England.

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