Consumer buying grow lights

Informed Grow Light Decisions

Picking Grow Lights for Indoor plants
Reading Time: 14 - 18 minutes (4062 words)

Growing plants indoors offers a plethora of benefits, yet presents a quintessential challenge – finding the right light source to ensure your green buddies thrive. Although the sun does an exemplary job outdoors, replicating the same indoors is a task. Enter grow lights, the beacon of life for your indoor garden. Amidst the myriad of manufacturers and product options, how do you decide which one suits your green endeavours best? Worry not, by understanding your plants' needs and the merits of different light considerations, you can make a well-informed decision. Let’s illuminate the subject to guide you through!

Understanding Your Plant's Light Requirements:

Before diving into the types of grow lights, it's imperative to grasp what your plants crave. Light for plants is akin to food for us, and different plants have varied light diets.

Light Spectrum:

We've discussed some aspects of the light spectrum in other articles, but plants utilize different wavelengths of light for various purposes so its good to get an understanding of the topic before considering a grow light purchase. Photosynthesis primarily employs light in the red and blue parts of the spectrum, and more recent research is showing that parts of the green spectrum are more valuable that previously realized. Full-spectrum lights can simulate a natural sunlight environment, benefiting the plant in more ways than one, but aren't always the only consideration.

Light Duration:

Light duration, often referred to as photoperiod, plays a crucial role in the growth and development of plants. It essentially signifies the length of time a plant is exposed to light within a 24-hour period. Different plants have diverse photoperiodic needs which are intrinsically linked to their lifecycle phases such as germination, vegetative growth, and flowering. The regulation of light exposure can trigger certain biological responses in plants. For instance, long-day plants require longer light exposure to initiate flowering, while short-day plants flower when the light duration is reduced.

In indoor gardening, controlling the light duration allows gardeners to manage the growth cycles of their plants meticulously. This control is particularly advantageous when growing plants with specific light duration requirements, enabling the gardener to mimic seasonal light changes and thereby inducing desired growth phases.

Understanding Daily Light Integral (DLI)

Daily Light Integral (DLI) is a crucial metric that amalgamates light duration and intensity to understand the total amount of light a plant receives in a day. It is measured in moles of light per square meter per day (mol/m²/d). DLI provides a clear depiction of whether the plants are receiving adequate light for photosynthesis and healthy growth. It's an indispensable tool for growers to optimize light exposure and ensure that plants receive the required amount of light for their specific growth stages.

In outdoor conditions, the DLI is influenced by factors like geographic location, time of the year, and weather conditions. However, in indoor gardens, growers have the ability to control the DLI by adjusting the light intensity and duration, which is pivotal for achieving optimal plant growth and development. By understanding and managing DLI, indoor gardeners can create the most conducive environment for plant growth, regardless of the external conditions, and drive better yields and plant health. Hence, DLI serves as a benchmark for growers to evaluate the effectiveness of their lighting system and make necessary adjustments to match the plants' light requirements precisely.

DLI Light Calculator

Light Intensity:

Light intensity is a crucial aspect of indoor gardening as it directly impacts the rate of photosynthesis, thereby influencing the growth, development, and yield of plants. One of the paramount factors to consider while examining light intensity is Photosynthetically Active Radiation (PAR), which refers to the light spectrum range (400-700nm) utilized by plants for photosynthesis. Unlike humans who perceive light in terms of brightness, plants "see" and utilize light differently, focusing more on the photosynthetically active radiation spectrum which encompasses the blue (400-500nm) and red (600-700nm) lights.

PAR offers a broad understanding of the usable light spectrum but doesn't provide insights into the quantity or intensity of light that reaches the plants. This is where Photosynthetic Photon Flux Density (PPFD) steps in. PPFD measures the number of PAR photons hitting a specific area (measured in micromoles per square meter per second - µmol/m²/s) of your plant canopy each second, rendering a precise understanding of the light intensity that your plants receive. A higher PPFD value indicates more light is reaching your plants, which could potentially lead to increased photosynthesis, provided other growth conditions are optimum.

Traditional light intensity measurements such as lux and lumens fall short when it comes to horticultural lighting as they are human-centric metrics, designed to quantify the brightness of light as perceived by the human eye. Lux and lumens consider the entire spectrum of visible light, with a pronounced sensitivity towards green light, which is not as crucial for plant growth. On the other hand, they lack sensitivity towards the red and blue parts of the spectrum which are vital for photosynthesis. This fundamental discrepancy makes lux and lumens unreliable indicators of light intensity for plant growth, highlighting the importance of utilizing PAR and PPFD as more accurate measures for assessing the effectiveness and suitability of grow lights in an indoor gardening scenario. Through these plant-centric metrics, gardeners can better understand and control the light environment, ensuring that their indoor plants thrive and flourish.


Tailoring Light Spectrum:

Tailoring the light spectrum specifically for the plants you are growing is an advancement in horticultural technology that has changed the game for indoor gardeners and commercial growers alike. This tailored approach allows for the optimization of light wavelengths to suit the particular needs of different plant species at various stages of their growth cycle. Utilizing the full spectrum of light, inclusive of the visible spectrum and the spectral edges of ultraviolet and infrared, can mimic the natural solar spectrum to foster healthy plant growth indoors.

With the advent of sophisticated LED grow lights, growers now have the ability to customize the light spectrum to match the specific needs of their plants. High-quality LED grow lights often come with adjustable spectral outputs, enabling growers to increase or decrease certain color bands of the light spectrum to promote particular plant behaviors. For instance, the blue spectrum is known to encourage compact, leafy growth, which is ideal for the vegetative stage of growth, while the red spectrum fosters flowering and fruiting, essential for the blooming phase.

Moreover, understanding the science behind Photosynthetically Active Radiation (PAR) is crucial when tailoring the light spectrum. By manipulating the light spectrum within this range, growers can potentially maximize photosynthesis, promoting faster growth, higher yields, and better plant health.

The tailoring of the light spectrum isn't just about promoting growth, but it's also about managing plant health, preventing diseases, and controlling pests. For example, UV light can help in managing powdery mildew and other fungal diseases. As indoor horticulture continues to evolve, the ability to tailor the light spectrum will become increasingly important, allowing growers to optimize conditions for plant growth, improve energy efficiency, and reduce operational costs.

This advanced control over the light spectrum has undeniably revolutionized indoor growing, offering a level of precision and customization that was previously unattainable. Whether for hobbyist gardeners or commercial cultivation, the ability to tailor the light spectrum according to the specific needs of the plants ensures that the artificial lighting environment is as close to natural sunlight as possible, or even better, optimized for maximum plant productivity and health.

Decoding the Growth Stage:

Understanding the various growth stages of plants is crucial for indoor gardening, especially when it comes to providing the appropriate light. Each growth stage has distinct light requirements which, if met accurately, can significantly enhance the growth, health, and yield of your plants. These stages primarily include the seedling stage, vegetative stage, and flowering stage.

Seedling Stage:

The seedling stage is the first phase of a plant's life, right after germination. During this stage, seedlings are tender and require a gentle, full-spectrum light to mimic natural sunlight. The goal is to provide a balanced spectrum that encourages strong root development and robust growth, setting a strong foundation for the plant's future stages. It's also important to note that excessive light intensity or incorrect spectrum can lead to stress or even damage to the young seedlings.

Vegetative Stage:

As plants move into the vegetative stage, their light requirements shift. This stage is all about growing bigger and taller, and to facilitate this, plants require a higher intensity of light, particularly in the blue spectrum. Blue light is known to promote lush, compact, and bushy growth, preparing the plants for a healthy flowering stage. LED are often chosen specifically for this stage due to their capacity to provide the necessary blue spectrum and intensity of light.

Flowering Stage:

The flowering stage is where plants focus on reproducing and creating flowers or fruits. During this stage, the light needs shift once again, now favouring the red part of the spectrum. Red light encourages flowering, fruiting, and enhances the yield. For many commercial growers, High-Pressure Sodium (HPS) lights or tailor-made LED lights with adjustable spectrum control are often favoured during this stage as they can provide the necessary red spectrum light which promotes and supports the flowering process.

By decoding the growth stage of your plants' gwoth and aligning the lighting conditions accordingly, indoor gardeners can significantly improve the health, growth, and yield of their plants. Tailoring the light spectrum, intensity, and duration to the specific needs of each growth stage ensures that the plants receive the right kind of light at the right time, setting the stage for a successful indoor gardening venture.

Measuring Your Space:

The size of your garden significantly impacts the choice of light type.

Area Coverage:

When embarking on the journey of indoor gardening, an imperative step is to measure the space you have dedicated for your new plant addiction. Unlikely Gardener often turns into Unlikely Gardening Addict, so the dimensions of your indoor gardening soace significantly impact the type and number of grow lights you'll need, ensuring that your plants receive adequate light for healthy growth.

Ceiling Height:

The height of the ceiling, or your overhead shelf height if growing on open shelving or in a plant cabinet is another vital factor as it determines how far your lights can be hung above your plant canopy. Taller spaces can accommodate a wider variety of LED light configurations which can be an important consideration when you want/need more light intensity, and this can also mean you can cover a larger area with a greater height. On the other hand, shorter spaces may be better suited for low intensity LED panels that can be positioned closer to the canopy without burning or causing heat stress to the plants, thanks to their cool operation. This is often a great option for veggie seedlings. The ability to adjust the height of your lights as your plants grow is essential to maintain the appropriate light intensity and coverage.

Moreover, the light distribution pattern also plays a role. Some lights distribute light more evenly across a wide area, while others focus light more directly below them, creating a spotlight effect. It's imperative to understand the spread of light to avoid hotspots and ensure even light distribution, promoting homogenous growth across your garden. This is one key factor when choosing any light, but especially LED lighting since the LED array and light-intensifiers on many bulb type lights creates limits on light effectiveness and efficiency.

Powering the Green: Energy Efficiency:

In the realm of indoor gardening, the phrase "Powering the Green" encapsulates the critical role that energy efficiency plays in fostering a sustainable and thriving indoor horticultural environment. As a linchpin for successful indoor cultivation, the choice of grow lights significantly impacts not only the health and productivity of the plants but also the energy consumption and operational expenses associated with indoor gardening. Among various types of grow lights, LED lights stand out for their superior energy efficiency, thus being often regarded as a pragmatic choice for the environmentally conscious and cost-sensitive grower.

LED Grow Lights have revolutionized the way we provide artificial light to plants by not only mimicking the spectrum of sunlight but doing so with far less energy. Unlike traditional lighting systems such as High-Intensity Discharge (HID) or Compact Fluorescent Lights (CFL), LEDs convert a higher portion of energy into usable light rather than wasting it as heat. This characteristic reduces the need for additional cooling systems, which, in turn, lowers the overall energy consumption. Moreover, LED lights have a longer lifespan, which means fewer replacements and reduced maintenance costs over time. They are capable of delivering the specific light spectrum that plants need for photosynthesis, and modern technologies allow for spectrum control to suit different growth stages, further optimizing energy use.

The journey towards "Powering the Green" entails a well-informed selection of grow lights that align with the principles of energy efficiency. By opting for energy-efficient LED grow lights, indoor gardeners are not only nurturing their green endeavours but also contributing to a broader narrative of energy conservation and environmental sustainability. The upfront investment in LED technology invariably translates to long-term savings, underlining the profound synergy between the thriving green and the powering light, encapsulated in the ethos of energy efficiency.

Energy Use Calculator

Other Considerations:

When venturing into indoor gardening, several other factors need your attention to ensure you are making a well-rounded decision regarding the selection of a grow light. These considerations are vital for not only ensuring the optimal growth of your plants but also for ensuring a hassle-free gardening experience.

Dimming and Light Control:

Modern LED grow lights often come with dimming features, allowing a better control over light intensity which can be crucial for the different growth stages of your plants. The ability to control light intensity can mimic the natural sunlight conditions, making it a conducive environment for plant growth. Furthermore, some advanced models offer programmable light schedules and spectrum control, providing an even more tailored light environment which can significantly contribute to better plant growth and yield.

Heat Management:

Heat management is a critical consideration as excessive heat can damage your plants or slow down their growth. LED lights typically generate less heat compared to HID or Fluorescent lights, which is beneficial in reducing the cooling costs and ensuring a suitable temperature for your plants. Moreover, a lower heat output means less evaporation, which could be beneficial in maintaining moisture levels especially in arid or heated indoor conditions.

Maintenance Costs:

Every type of grow light comes with its own set of maintenance needs. For instance, HID or Fluorescent lights may require bulb replacements over time, which can add to the cost. LED lights, on the other hand, have a longer lifespan, often 50,000 hours or more, and lower maintenance needs, making them a cost-effective choice in the long run. It’s essential to factor in these maintenance costs as they can impact the overall cost-effectiveness of your indoor gardening venture.

Warranty and Manufacturer Support:

Investing in grow lights with a good warranty and manufacturer support can be a wise decision. It not only ensures that you are protected against any manufacturing defects but also provides peace of mind knowing that you have the necessary support when needed. Manufacturer support can be invaluable, especially for beginners who may need guidance on using the grow lights effectively. One of the problems with the plethora of cheap "full spectrum grow lights" on the market from places like Amazon, Wish, and Ali Baba is that warranty support is often questionable at best, especially after the exchange or return period. Almost anyone can offer grow lights via drop shipping on Amazon and support is completely nonexistent. Big box retailers provide no intelligence either, "Buyer Beware" is the thing to always keep in mind buying cheap, popular lights. Even the most popular brands that everyone recommends are generally complete garbage. They work, usually, but don't expect any knowledge from the vendors in 99% of cases.

User Reviews and Community Recommendations:

Perusing through user reviews and seeking recommendations from experienced indoor gardeners can provide minimally helpful insights into the performance and reliability of different grow lights. Engaging with forums, social media groups, or local gardening communities can be confusing and a difficult way to learn from others' experiences because much is based off of dated technology or specifications, popular product opinions, and anecdotal usage information.

Light Science is complex and most consumers know little to nothing about the science, and those with a little more knowledge are often only a step or two ahead of the masses. Most consumer light manufacturers are not experts on lighting either, especially as it relates to gardening. They know their product output spectrum, but that's often the only thing they can discuss. I've contacted most major manufactures regarding their products and various specifications and many don't even grasp the concept of Lumens, LUX, PAR or PPFD. Many lighting professionals use lighting terms incorrectly as well. Some of this is part of their marketing strategy; selling cheap underpowered products results in big money.

If you want great grow light advice talk to hydroponic shops, professionals in commercial greenhouse management, or commercial cannabis growers. Even home cannabis growers are more knowledgable than almost all typical garden center staff, or big box retailers.

Certifications and Safety:

When selecting grow lights for your indoor gardening endeavors, understanding the various certifications and ratings can be crucial. These certifications and ratings indicate the safety, quality, and suitability of a device for certain conditions. Here’s a look into some important certifications and ratings:

IP Ratings (Ingress Protection):

IP ratings are utilized to define levels of sealing effectiveness of electrical enclosures against intrusion from foreign bodies (tools, dirt etc) and moisture. Here are the details regarding IP54, IP65, IP66, and IP67:

  • IP54:
    • Dust Protection: Protected against limited dust ingress.
    • Water Protection: Protected against water spray from any direction.
  • IP65:
    • Dust Protection: Dust tight.
    • Water Protection: Protected against low pressure water jets from any direction.
  • IP66:
    • Dust Protection: Dust tight.
    • Water Protection: Protected against high pressure water jets from any direction.
  • IP67:
    • Dust Protection: Dust tight.
    • Water Protection: Protected against immersion between 15 centimeters and 1 meter in depth.

These ratings are crucial when considering the environment in which your grow lights will be used. For example, in a high-humidity environment or a setup where water spray is common, opting for grow lights with higher IP ratings (like IP66 or IP67) would be beneficial.


ETL Certification:

ETL certification indicates that the product has met the minimum requirements of widely accepted product safety standards, as determined through the independent testing by a third-party organization. Moreover, the manufacturer agrees to periodic follow-up inspections to verify continued compliance. Having an ETL certification ensures that the grow light has been tested and deemed safe to use.

UL Certification:

UL (Underwriters Laboratories) certification is a widely recognized standard for product safety. Products that carry the UL certification have been tested rigorously to ensure that they meet the safety standards. This certification is a testament to the product’s adherence to recognized safety standards and indicates a level of trustworthiness in its operation.

When purchasing grow lights, looking for those with ETL or UL certifications can provide an added level of assurance regarding the safety and quality of the product. This is especially important in reducing the risk of electrical hazards in your indoor gardening setup.

RoHS (Restriction of Hazardous Substances):

RoHS certification ensures that the product is free from specific hazardous materials. This is essential for both environmental sustainability and personal safety.

CE (Conformité Européene):

A CE mark indicates that the product complies with European health, safety, and environmental protection standards. Even if you are outside Europe, a CE mark is a good indicator of product quality.

FCC (Federal Communications Commission):

FCC certification is essential to show that electromagnetic interference from the product is under limits approved by the federal body. It ensures that the grow light won't interfere with other electronic devices.

DLC (DesignLights Consortium):

DLC certification helps in identifying the commercial LED grow lights that meet specific performance and efficiency standards. It’s a reliable indicator of light quality and energy efficiency.

Energy Star:

Products with the Energy Star label meet strict energy efficiency guidelines set by the U.S. Environmental Protection Agency. This certification can help you save money on energy bills.

LM-79 and LM-80:

These are methods of measuring the lumen maintenance of LED light sources. LM-79 covers the electrical and photometric testing, while LM-80 covers the lumen depreciation testing. These certifications provide insights into the long-term performance and reliability of LED lighting products.

PSE (Product Safety Electrical Appliance & Material):

This is a Japanese certification indicating that the product meets specific safety requirements. It’s a crucial certification for products sold in Japan but also signifies a certain level of quality and safety.

C-Tick and RCM (Regulatory Compliance Mark):

These are Australian certifications indicating compliance with the local electrical safety and electromagnetic compatibility requirements.

MET (Metropolitan Electrical Testing Laboratory):

Like UL and ETL, MET certification indicates compliance with recognized safety standards.

It's advisable to consider grow lights that have one or more of these certifications, as they provide assurance regarding safety, quality, and performance. While it may come at a higher upfront cost, investing in certified products can save you from potential hazards and additional costs in the long run.

Final Verdict:

The pathway to a thriving indoor garden largely hinges on the quality of light your plants receive. Therefore, the process of selecting the right LED grow light is a critical determinant of your garden's success. This decision merits a blend of understanding your garden's needs, the science of plant growth, and the technical specifications of available lighting solutions. It's a venture where your budget, long-term expectations, and willingness to manage the lighting system come into play.

First and foremost, a well-informed budget allocation is crucial. While upfront costs might seem steep, especially for high-quality LED grow lights, the long-term benefits often outweigh the initial investment. Lower energy bills, lesser heat generation, and reduced need for cooling systems are but a few of the advantages. Moreover, high-quality LED grow lights with certifications like ETL, UL, or RoHS ensure safety and performance, potentially reducing future replacement or maintenance costs.

Tailoring your choice based on the growth stage of your plants can significantly impact their health and yield. Modern LED grow lights often come with adjustable spectrum controls allowing for a seamless transition from the vegetative to the flowering stage, ensuring that your plants receive the optimal light spectrum at each phase of their growth.

Space considerations are equally vital. The size of your garden and the ceiling height can greatly influence the effectiveness of your lighting solution. Make sure the lights provide adequate coverage, and the intensity is just right for all plants, regardless of their position in the garden.

Energy efficiency is another significant factor. LED grow lights are at the forefront of energy-efficient lighting solutions, and opting for them can significantly lower your energy bills, a saving that accumulates over time.

Lastly, peer through reviews, engage with indoor gardening communities, and don't hesitate to reach out to manufacturers for clarifications. The more information you have, the better your decision will be. Remember, a well-lit garden is a well-grown garden. By taking time to evaluate your options, considering your space, and understanding your plants' needs, you're setting a solid foundation for a thriving indoor garden. Making an informed choice on LED grow lights not only illuminates your green space but also brightens the prospects of lush, healthy growth within your indoor oasis.

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