Types Of Grow Lights

Grow lights


When I was about to begin my herb growing journey, I didn’t know that grow lights were necessary, especially for indoor gardening. Now I know! And if you are just to begin the process, you need the information at your fingertips. 

These are artificial lighting systems that simulate the natural sunlight necessary for indoor environment growing setup. The specialized lights  provide your plants with light where sunlight may be limited. In hydroponics, indoor gardening, and cultivating plants in spaces where sunlight is insufficient, these lights are a must have. 

How Grow Lights Work

Grow lights work by emitting electromagnetic radiation, primarily in the visible light spectrum, to provide the energy needed for photosynthesis. Photosynthesis is the biological process through which plants convert light energy into chemical energy, producing glucose and oxygen. Natural sunlight contains a broad spectrum of light, including ultraviolet (UV), visible, and infrared (IR) wavelengths. While grow lights aim to mimic this spectrum, not all lights are created equal.

Various types of grow lights are available, each with its unique advantages and applications. Common types include fluorescent lights (such as T5 and CFL), high-intensity discharge (HID) lights (including metal halide and high-pressure sodium), LED lights (full spectrum, red and blue, COB LEDs), induction lights, and plasma lights.

These lights are effective and can successfully support plant growth when you use them appropriately. In my hydroponic growing journey, I realized that their effectiveness depends on factors such as light spectrum, intensity, duration, and the specific needs for each plant. Now that you know how the lights work, let’s now delve on the types of grow lights.

Common Types Of Grow Lights

There are several types of grow lights for use in indoor gardening and hydroponics. Their purpose is to provide the necessary light spectrum for plant growth. Each type has its own advantages and is suitable for different stages of plant development. Here are some common types of grow lights:

Fluorescent Lights

There are two types of fluorescent lights that you can consider for your indoor or hydroponic gardening;

  • T5 Bulbs

In my testing, I found that the T5 is suitable for seedlings. The reason is as it produces less heat, which is the perfect requirement for young p `1lants. Although they produce minimal heat, the bulbs have a robust distribution of light. Also, T5 is efficient, durable and cost-effective. They hang around for a longer time, thus saving your pocket.

  • CFL (Compact Fluorescent Lamp)

The CFLs are also great for indoor and greenhouse gardening. I also discovered tjat the CFLs use less power, hence a reduced electricity demand and bills. If you use the lamps, you also reduce greenhouse gas emissions and mercury. The CFLs contain a minute amount of mercury, about  4 milligrams in each bulb. Another benefit is that these lights are affordable and suitable for smaller growing spaces. They are also suitable for seedlings and young plants.

Pros Of Fluorescent Lights

  • Fluorescent lights are generally more energy-efficient than some other types of grow lights, such as incandescent bulbs. 
  • Fluorescent lights emit less heat compared to high-intensity discharge (HID) lights like Metal Halide or High-Pressure Sodium.
  • The fluorescent lights provide a good balance of both blue and red spectrums, making them suitable for both vegetative and flowering stages of plant growth. 
  • The lighting systems are more affordable to set up compared to some high-end lighting options.
  • CFLs, in particular, are compact and can be easily installed in small spaces, which is ideal for seedlings, clones, or plants with limited vertical space.

Cons Of Fluorescent Lights

  • Fluorescent lights have lower light intensity compared to HID lights, which can affect high-light-requiring plants or large-scale operations.
  • Fluorescent light penetration is shallow thus a con for plants with dense canopies.
  •  While fluorescent lights cover a broad spectrum, they may not provide the same range as some other types of lights, such as full-spectrum LEDs. 
  • Fluorescent bulbs have a limited lifespan, and require frequent replacement. Such maintenance procedures add to the overall operational costs.
  • The fluorescent bulbs contain trace amounts of mercury, posing an environmental concern. They require proper disposal methods to prevent mercury contamination.

Metal Halide (MH)

Metal Halide or MH lights are grow lights that are rich in the blue spectrum. They have a high density discharge hence great for indoor gardening and horticulture. They comprise a bulb with   quartz arc tube filled with a mixture of metal halide gasses. These gasses include compounds of metals like mercury, sodium, and rare earth elements. 

Due to their strength and ability to penetrate into the vegetation, growers use them during the vegetative stage. These lights produce a broad spectrum of light that closely mimics natural sunlight, making them suitable for a wide range of plants. 

 In my case, I installed the CFL lamp for seedlings and later mounted the MH when the herbs reached the vegetative stage.  

Components and Operation:

Pros Of Metal Halide Grow Lights

  • The MH lights emit a balanced spectrum of light, including a significant amount of blue light. This spectrum is beneficial for promoting vegetative growth and healthy foliage in plants.
  • MH lights are versatile and are useful throughout the entire growth cycle of plants. They are particularly effective during the vegetative stage when plants need more blue light for strong and compact growth.
  • Metal halide lights have a relatively high CRI, which means they can accurately represent the colors of objects. This can be advantageous for growers who want to observe the overall health and development of their plants.

Cons Of Metal Halide Grow Lights 

  • Metal halide lights are not as energy-efficient as some other types of grow lights. They produce a significant amount of heat, and a substantial portion of the energy consumed is not converted into usable light for plant growth.
  • MH bulbs have a limited lifespan when you compare to some other grow lights. Over time, their light output decreases, and bulbs need to be replaced to maintain optimal performance.
  • Metal halide lights generate a considerable amount of heat. This heat prompts you to install proper ventilation and cooling systems to prevent excessive heat buildup, which has a cost impact.
  • While MH lights provide a good amount of blue light, they are deficient in the red spectrum, which is crucial for flowering and fruiting stages. Many growers use MH lights in conjunction with other light sources, such as high-pressure sodium (HPS) lights, to cover the full spectrum of light required for the entire growth cycle.

LED (Light-Emitting Diode) Lights 

There are three types of LED or Light Emitting Diode lights; 

  • Full Spectrum LED

These lights provide a complete spectrum of light suitable for the entire plant growth cycle. They are energy-efficient, plus you can tailor them to specific plant needs. 

  • Red and Blue LED

These lights are beneficial for specific stages of plant growth. The blue light promotes vegetative growth, while red light is crucial for flowering and fruiting.

  • COB LED (Chip on Board)

The COB LED lights use multiple LED chips in one module, providing a high-intensity and uniform light output.

Pros Of LED Lights 

  • The LED lights are highly energy-efficient, converting a significant portion of the electricity they consume into usable light for plant growth.  
  • They have a much longer lifespan than traditional light sources. They can last tens of thousands of hours, reducing the frequency of bulb replacements and maintenance costs.
  • The lights have a versatile spectrum which allow growers to tailor them to the needs of plants during different growth stages. The spectrums range from low to full hence covering the entire range of light required for both vegetative and flowering phases.
  • They have low heat emission hence easier to control the temperature in the growing environment and reduce the risk of heat stress to plants.
  • The LEDs have a compact and lightweight design making them suitable for various setups, including vertical farming and environments with limited space.
  • They have instant On/Off which allows full brightness immediately you turn them on. In essence they do not require a warm-up period. 
  • You can customize LED fixtures to fit specific ratios of red, blue, and other wavelengths depending on the plant’s growth stage.

Cons Of LED Lights

  • They are costly to set up. 
  • Their quality and spectrum vary making it difficult to buy the best.
  • The lights have a less penetration capacity for dense canopies.
  • It is not easy to manage LED heat to a proper level. 
  • LEDs can be sensitive to environmental conditions, and factors such as excessive heat or poor ventilation can affect their performance. To overcome this challenge, follow manufacturer recommendations for installation and usage.

Induction Lights

Induction lights are not as common in horticulture, but they are known for their long lifespan and energy efficiency. There are several of these that I found in the market;

  • Magnetic Induction Lamps

These lamps use a magnetic field to induce the discharge of gas within the bulb, producing ultraviolet (UV) light. The UV light then interacts with a phosphor coating inside the bulb, generating visible light. Magnetic induction lamps are common in indoor gardening and plant cultivation. They provide a balanced spectrum of light suitable for various growth stages.

  • Electromagnetic Induction Lamps 

These are similar to magnetic induction lamps, but use electromagnetic fields to excite gasses within the bulb. The excited gasses emit UV light, which converts into visible light by the phosphor coating. Electromagnetic induction lamps are utilized in horticulture for providing the necessary light spectrum for plant growth. They are often chosen for their energy efficiency and longevity.

  • Plasma Induction Lamps 

The Plasma induction lamps use a combination of microwaves and magnetic fields to create plasma, which emits visible light when it interacts with a phosphor coating. There are various applications for these lamps throughout the plant growth. Their advantage is that they have a high efficiency and can produce a broad spectrum of light suitable for all growth stages.

  • High-Frequency Induction Lamps

The high-frequency induction lamps operate at higher frequencies, typically in the radiofrequency range, to induce the gas discharge within the bulb. This design can lead to improved efficiency and light output. Their applications include indoor gardening and other forms of horticulture because of their ability to provide a consistent and high-quality light spectrum.

  • Low-Frequency Induction Lamps 

Low-frequency induction lamps operate at lower frequencies and are reliable and have a longer life. They use magnetic fields to induce gas discharge. These lamps find applications in indoor gardening and plant cultivation, offering a reliable and long-lasting lighting solution.

  • Circular Induction Lamps

The circular induction lamps have a circular form and can provide a more uniform distribution of light. They often come in various sizes to accommodate different growing spaces and are suitable for various horticultural setups. That includes vertical farming, where uniform light distribution is crucial.

Pros Of Induction Lights

  • They have a long lifespan.
  • The lights are energy efficient.
  • Induction lights have a low heat emission, which favors most plants.
  • They are instant start lights and do not require time for warming.
  • The lights have a wide spectrum.
  • They are low maintenance lights.

Cons Of Induction Lights

  • Induction lights have a limited intensity.
  • They have limited light penetration hence disadvantageous for dense canopies.
  • These lights come with an upfront set up cost.
  • The bulbs have specific applications.

Plasma Grow Lights  

Plasma lights are relatively new to the market and provide a broad spectrum of light. Let me bring you the pros and cons of these grow lights.

Pros Of Plasma Grow Lights 

  • Plasma grow lights have a high efficiency in converting energy into light, making them a cost-effective option over the long term.
  • They have a broad spectrum coverage which mimics natural sunlight. 
  • The lights provide a balanced mix of wavelengths beneficial for various stages of plant growth.
  • Plasma lights have a longer lifespan compared to some traditional lighting sources, reducing the frequency of replacements and maintenance costs.
  • They emit less heat compared to certain high-intensity discharge (HID) lights, helping maintain a more controlled temperature in the growing environment.
  • Plasma lights can start instantly without a warm-up period, allowing for precise control over the lighting schedule without impacting plant growth.
  • The grow lights can produce high-intensity light, providing ample brightness for optimal plant development.
  • They have an excellent light penetration, thus great for dense canopies.
  • The lights have a flexibility to adjust its spectrum.
  • Plasma lights are suitable for various growth stages, including vegetative and flowering stages.
  • These are energy efficient grow lights. 

Cons Of Plasma Grow Lights

  • Plasma grow lights often have a higher initial investment compared to some other lighting options.
  • They have a limited availability and variety when you compare them to more established technologies like LEDs.
  • They require specific maintenance requirements, and finding replacement parts might be more challenging than for other common lighting technologies.
  • Some plasma grow lights can be bulkier or heavier than other lighting options, potentially requiring additional considerations for installation.
  • They may require additional cooling systems to dissipate heat effectively, adding to the complexity of the setup.

Wrap Up

There are various grow lights that you can consider for your herbs or horticultural growing. The most common are the plasma, LEDs, CFLs, induction lamps, and metal halides. There are more upcoming technologies. Before selecting the ideal lighting, consider availability, cost,and maintenance. 

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