How to Use LED Grow Lights

How to Use LED Grow Lights

 LED lights have proven to be a great way to cultivate plants without relying on natural sunlight. Plants require a specific growth light spectrum for photosynthesis, which is not always available from the sun.

These artificial lighting sources help plants by supplying the required light to extend their growth duration. A grower can speed up growth and increase yields dramatically by installing an LED grow light in his garden. Below is a guideline on how to use LED grow lights.

How Do LED Grow Lights Function?

LED grow lights provide plants with the optimal light spectrum for their growth and development. They emit a specific plant light spectrum to enhance photosynthesis, influence morphology, and promote higher yields. These wavelengths mimic natural sunlight, but the lamps tailor the lighting conditions to boost the plants’ growth stages. Below you’ll find a grow light spectrum guide to help you understand the many wavelengths that comprise these products. 

Red Light

Red light occurs at wavelengths of 600 to 700 nanometers (nm). It is essential for photosynthesis. Chlorophyll pigments absorb light to drive the primary photosynthetic reactions. This process stimulates the synthesis of energy-rich molecules to produce carbohydrates for use in growth and development.

Blue Light

The blue light spectrum for plants ranges from 400 to 500 nm. Light is vital for photosynthesis and plant growth as cryptochromes and phototropin absorb it. These two play a crucial role in photomorphogenesis. Blue light regulates various processes, such as the growth of plants in response to light, stomatal opening and closing, and the synthesis of specific proteins involved in growth regulation.

Green Light

Green light’s wavelengths range from approximately 500 to 600 nm. Chlorophyll pigments do not strongly absorb this light compared to red and blue light. Instead, plants reflect this light and transmit it through their tissues. This process is what gives plants their characteristic green color. This light regulates plant architecture and leaf expansion. It can penetrate deeper into the plant canopy to reach lower leaves and promote their growth. It also affects photomorphogenesis and helps maintain a balance between red and blue light responses.

Far Red

The far-red light spectrum for plant growth ranges from 700 to 800 nm. This light affects plant growth and flowering, particularly in relation to photoperiodic responses. Far-red light regulates the flowering process and influences the timing of other developmental events. It does so by controlling the phytochrome system, a light-sensitive protein that helps plants sense changes in day length.

Once activated, the protein affects plant height, flowering time, and other developmental processes. Growers can influence the transition from the vegetative to the flowering stage by manipulating exposure to light.

Guidelines on How to Use Grow Lights

Every grower must know how to use LED grow lights well to produce the desired results and raise crop efficiency. Below are different things growers need to remember to take full advantage of lights and ensure maximum yield.

  • Light Intensity

Light intensity measures the number of lumens that reach a square foot. Plants have varying light intensity requirements at different growth stages besides the wavelength. Seedlings require lower light intensities compared to mature plants. However, the amount varies with the type of plant.

Determining the light intensity needed for the specific plants before selecting a grow light is important. Knowing this particular requirement of your plant will help you decide how many bulbs you need for a given space. 

  • Wattage

This characteristic refers to the power consumption of the grow light. The wattage required depends on the desired light intensity and spectrum. Higher-wattage lights generally produce higher light outputs. However, one should strike a balance to avoid excessive heat generation.

Fortunately, LED grow lights are energy-efficient, which means they are able to provide a high light output while consuming less power compared to traditional lighting systems. This aspect makes them better and more efficient than conventional grow lights.

  • Coverage Area

Every grower should check the area that the grow light will cover. The coverage area varies depending on the desired light intensity and the distance from the plants. One should read the manufacturer’s guidelines to determine the coverage and the number of bulbs required for a particular space. 

  • Price Points

LED grow lights come at varying price points. However, one should strike a balance between quality and cost-effectiveness. Growers should not just go for the cheapest option. They should check reliability and performance within the stated budget.

Proper Placement and Distance for Optimal Light Distribution

Proper grow light placement and distribution ensure all plants get sufficient light. Every grower should be meticulous in their planning to maximize the efficiency of their artificial lighting.

One should always start with the manufacturer’s guidelines when installing lights. These guidelines provide the recommended height, distribution, and distances to get the best results with their bulbs. In addition, the grower may also consider the following areas.

Hanging Height

This distance is the height between the canopy of plants and the LED grow lights. Depending on their crops, growers should follow the manufacturer’s recommendations for the specific model they wish to use. The hanging height can vary depending on factors such as light intensity, coverage area, and the growth stage of the plants.

Generally, hanging the lights higher during the early growth stages or for seedlings is mandatory to avoid excessive light intensity that could potentially damage the plants. As the plants grow taller, lowering the lights’ hanging height helps maintain an appropriate distance and provide adequate light coverage.

Spacing Between Lights

The spacing between LED grow lights enables the grower to achieve uniform light distribution. Effective light distribution prevents shadows and allows light to reach all canopy parts. The recommended spacing between lights can vary depending on the light intensity, coverage area, and specific needs of the plants being grown.

Manufacturers often provide guidelines regarding the ideal spacing for their products. The grower should follow these recommendations to achieve optimal light uniformity and avoid any light gaps or hotspots.

Coverage Area

Manufacturers usually specify the coverage area for their products. They account for a specific light spectrum for plants, intensity, and hanging height. However, growers may want to make adjustments depending on the plant type and their enclosed garden’s shape. They should always consider the dimensions of the growing area and the desired light intensity within. Besides, growers should keep the distance below the maximum stated coverage area to get adequate light to all plants.

Reflective Surfaces

Surfaces that do not benefit from it, such as walls, absorb part of the light as well. Growers can redirect this to the plants to cover areas that may have shadows or inadequate light. They can achieve this by installing reflective surfaces in their growing areas.

Common reflective materials include white paint, Mylar, or reflective films. These surfaces reflect the light back onto the plants, ensuring more of it reaches the lower leaves for lateral growth. When a grower maximizes light reflection, they optimize light distribution and improve the overall performance of their LED grow lights.

Light Adjustments as Plants Grow

As plants grow and develop, the grower may need to make adjustments to the hanging height and spacing of the LED grow lights. These changes ensure that the light remains at an appropriate distance from the canopy and provides uniform coverage.

Newer LED light technologies have made light adjustments easier. They come with a light-intensity regulator built into the system. Therefore, if the bulb’s hanging distance is right, one just needs to lower the light intensity without moving the bulb. It is convenient, faster, and safer than moving the lighting fixtures.

How to Monitor and Adjust Light Levels

Monitoring the growth of the plants and making necessary adjustments to prevent light burn or inadequate light exposure is paramount for any indoor garden. In this sense, growers are responsible for maintaining an optimal distance throughout the growth cycle. Doing this promotes healthy development and maximizes the potential of the plants.

Many growers use light sensors or light meters for easy monitoring. Light sensors measure the light wavelengths most relevant for plant photosynthesis and growth. This measure refers to light intensity within the PAR range, between 400 and 700 nanometers. On the other hand, light meters, also known as lux meters or foot-candle meters, measure the intensity of light in units such as lux. Sensors capture the light and show the measurement on their displays, helping growers determine the light intensity reaching specific corners of the greenhouse.

Which Is the Accurate Light Intensity and Duration?

Growers should adjust light duration and intensity based on the growth stage to speed up vegetative growth, induce flowering, and maximize yields. The optimum adjustments vary from one plant type to another. However, a few features apply across the board, as discussed below:

  • Light Intensity for Vegetative Growth

Plants require higher light intensities to support robust leaf and stem development during the vegetative phase. Higher light levels also stimulate photosynthesis. On the other hand, increased photosynthesis leads to increased energy production and nutrient absorption.

Experts recommend light intensities between 400 and 600 micromoles per square meter per second (µmol/m²/s) of the red grow light spectrum for optimal vegetative growth.

  • Light Intensity for Flowering          

Light intensity requirements may differ as plants transition from the vegetative phase to the flowering stage. One may lower the light intensity during flowering to help trigger the reproductive processes. Lower intensity quickens the development of flowers and fruits as it signals the plants that it is time to shift their energy allocation toward reproductive growth. The recommended light intensity for flowering typically ranges from 200 to 400 µmol/m²/s of the red and far-red growth light spectrum.

  • Photoperiod Manipulation

Besides adjusting light intensity, the grower should also adjust the duration of light exposure. This factor is also known as the photoperiod and influences plant growth at different stages. Most plants require a balance of light and darkness to thrive, but the number of hours on either side varies.

During the vegetative phase, one should consider an LED grow light spectrum photoperiod of 18–24 hours of light and 6-0 hours of darkness. This extended light period supports continuous growth and development. However, when transitioning to the flowering stage, reduce the light period to 12 hours of light. The 12 hours of darkness help initiate the flowering process. One can maintain this photoperiod through the maturing period.


LED grow lights can help speed up growth and enhance yields. However, growers should know the right Kelvin light spectrum also affects plants at every stage of their growth. Being aware of this and all of the abovementioned distance-related considerations can help indoor garden enthusiasts maximize plants’ growth and yield potential.

When choosing LED grow lights, one should determine the required intensity, spectrum, and number of bulbs for the greenhouse. Growers need to also monitor growth and adjust light intensity and duration accordingly. Lastly, it is advisable to research the plants in order to know the optimal grow light Kelvin to obtain the best yields.

Leave a comment

Your email address will not be published. Required fields are marked *