To Dim Or Not To Dim Your LED Grow Lights

Optimizing Light Delivery for Specific Needs

• Daily Light Integral (DLI) is the key: While light intensity fluctuates throughout the day, the total amount of light received by plants over a 24-hour period (DLI) is the primary lighting factor influencing growth. Dimming or running lights for fewer hours can both achieve the same DLI.
• Dimming benefits in specific scenarios: Dimming is advantageous on moderately dark days to supplement natural light, during light-sensitive growth stages like rooting clones/cuttings, for crops with varying light requirements, and for aesthetic reasons in the grow space.
• Consider before dimming: Cost and complexity increase with dimming due to additional data cables/mesh connectivity equipment and potential controller upgrades. While dimming can turn most LED lights off, a contactor is still most reliable for complete darkness during the night cycle.
• Dimming is situational: Dimming isn’t universally necessary but shines in setups with high-intensity supplemental lighting, changing crops, or various growth stages.
• Additional Considerations: Longevity of LEDs is minimally improved by dimming, but power limitations might necessitate dimming to manage overall energy usage.

Growers strive to provide their plants with the perfect amount of light. LED lights offer excellent control and efficiency, but the question arises: Is dimming necessary for optimal plant growth? We delve into the world of dimming for LED grow lights, exploring its benefits, limitations, and practical considerations to help you determine if dimming aligns with your specific growing setup and goals.

Understanding Daily Light Integral (DLI)

Before diving into dimming, it’s crucial to remember that the total amount of light plants receive over a 24-hour period, known as Daily Light Integral (DLI), is the key factor influencing growth. Whether this DLI is managed through decreasing or increasing the hours of full-power light or dimming lights run for longer hours typically has minimal difference. Plants are adept at adapting to fluctuations in light intensity throughout the day, as long as the overall DLI target is met. However, significant variations (e.g. more than 4 times the difference between bright and dark periods) can negatively affect light use efficiency.

When Dimming Becomes Advantageous

While DLI remains the primary concern, dimming offers several advantages in specific scenarios:

• Variable Sunlight: On moderately dark days, dimming allows you to supplement the natural light, ensuring plants receive the desired DLI without exceeding it. This is especially beneficial during transitional periods between seasons when natural light levels fluctuate significantly.
• Light-Sensitive Growth Stages: Unrooted cuttings are susceptible to damage from excessive light. Dimming provides a gentle light intensity during this crucial stage, preventing photobleaching and promoting healthy root development, while allowing stronger light once roots are established for optimal growth.
• Crop-Specific Requirements: Different plants have varying light requirements. For instance, shade-loving plants may thrive under lower light intensities compared to sun-loving crops, and lettuce needs far less light than tomatoes. Dimming helps tailor the light intensity to match the specific needs of each crop, potentially alongside sensor-based controls for even greater precision.
• Aesthetic Considerations: Gradual dimming transitions between light levels can create a more visually appealing environment within the grow space, particularly for those working in the grow room for extended periods.

Factors to Consider Before Dimming

While dimming provides valuable benefits in certain situations, it’s not a universally necessary feature. Here are some key factors to take into consideration:

• Light Intensity: If your grow setup relies primarily on natural sunlight with a relatively small amount of supplemental LED lighting, the additional benefit of dimming might be minimal. However, in setups with high supplemental lighting (e.g., cannabis or tomato growers, or very dark environments), the potential for precise light control through dimming becomes more significant. In these scenarios, even slight adjustments in light intensity can have a noticeable impact on plant growth and development, and the efficiency with which the plants can use more light.
• Cost and Complexity: Dimming adds cost to your lighting system due to required data cables and potential adjustments to your environmental controller. Installation might require additional steps and may involve troubleshooting initial compatibility issues. While the cost increase from adding dimming cables is typically around 3%, it’s important to factor this into your overall budget.
• On/Off Alternative: DLI and overall light use can be reduced by scheduled or automated turning off of lights, instead of dimming. Especially for less intense lighting setups, this can be a simpler approach with less cost and equally effective end results.
• Functionality: While dimming can turn lights completely off, a contactor that cuts power during dark hours remains advisable for the most robust and reliable scheduling. This ensures a complete blackout period for plants that require strict photoperiods, preventing accidental light exposure during the dark cycle.

The Final Verdict: Dimming is Situational

Dimming shouldn’t be considered an automatic requirement for every grow setup. It’s a valuable tool that shines in specific situations, particularly when:

• Crops have varying light requirements throughout their growth cycle.
• High-intensity supplemental lighting is used, making precise control over light intensity more critical.
• Specific growth stages necessitate lower light intensities, such as during the rooting phase of cuttings.
• Maintaining a visually appealing grow space is a priority.

The longevity of LEDs is minimally improved by dimming, but a negligible benefit in terms of extending the already long lifespan. Power limitations might necessitate dimming in situations where other equipment competes for electricity. Furthermore, dimming lights during peak power consumption periods can help manage overall energy usage within your facility.

Existing environmental control systems may be more easily integrated with an automated on/off control approach guided by a light sensor, i.e. bright sunlight makes the LEDs turn off and low natural light levels make the LEDs turn back on to 100%. For less intense LED lighting installations, this on/off fluctuation is a moderate enough swing in total intensity received by the plants to be perfectly adequate.

Carefully evaluate your crop types, existing light setup, and budget constraints before deciding if dimming aligns with your needs. TotalGrow’s lighting experts are happy to assist you in determining the best approach for your specific grow environment, considering factors like the number of lights, wiring runs, and controller compatibility to ensure a smooth and efficient implementation. 

Innovative Solutions, Personalized Guidance

TotalGrow offers a wide range of dimmable LED grow lights and environmental controllers, along with expert support to guide you through the selection and installation process. We are committed to helping you achieve optimal plant growth and maximize efficiency in your grow operation with the minimum needed investment.

By understanding the nuances of DLI, the specific advantages of dimming, and the associated considerations, you can make informed decisions about optimizing light delivery for your plants. Remember, the goal is to provide the ideal light environment for your specific crops while maximizing efficiency and ensuring the overall health and productivity of your grow at the minimum necessary cost. Consult with us to see if your operation will benefit from dimming your LED grow lights.

FAQ: Dimming Your Grow Lights