Wattage of an LED determines the electrical energy input that a light requires. It is a measure of the LED’s energy consumption but not the light output. When buying incandescent bulbs, the bulb’s wattage indicates the brightness of the bulb. The higher the wattage of an incandescent bulb, the brighter the bulb would be. But with LEDs, the standard of measuring the brightness is different. The wattage of an LED doesn’t directly correlate to lighting performance. Sometimes, lumens are used to measure LED light bulb brightness. But lumens are not perfect measurements for determining the brightness of a light. Lumens only indicate the light emitted at the source, but do not measure the amount of light output falling on a given area. In practical applications such as when choosing LEDs for growing plants, what matters is the amount of usable light reaching per square foot of the growing area.

Wattage of LEDs 

When comparing LEDs to traditional bulbs, the wattage specifications are not same. For example, a 40 watt LED light is not similar to a 40 watt incandescent bulb. For a 40 watt incandescent bulb, the LED wattage equivalent would be much less. Since LEDs are designed to consume less energy, they emit more light for fewer watts. That means they use less watts to produce the same brightness compared to an incandescent bulb. So, if gardeners are replacing incandescent with LEDs, they can consider lesser wattage bulbs.

Another misconception is high wattage LEDs give a higher light output. This is again a wrong notion because the LED light output also depends on several other factors like LED chip used, component quality, heat sink, wavelength output, color accuracy as well as many other factors. LED light output also depends on the number of lumens the LED is rated to emit. In fact, with an increase in wattage, LEDs have a problem with excess heat dissipation and over consumption of electricity. So, to get a brighter light, one cannot just put more power in an LED. Also, it is important to note that wattage rating of LED lights is not consistent across different manufacturers. So, if you are comparing two LED lights based on the wattage, remember, you’re only looking at part of the story. For a 40 watt incandescent bulb equivalent, some manufacturers may create 6 watt lights with higher lumens whereas others may produce 8 or 9 watts with lower lumens. 

LED Wattage per Square Foot of Garden Space

Choosing LEDs to grow plants can yield better results as long as a proper LED lighting setup is used by gardeners. Since lighting requirements differ from one crop to another, growers should first know their lighting needs by considering crop type, garden area, growth stage, effective light height, greenhouse structure as well as some other metics. After thorough analysis of these factors, growers should plan to get the most efficient lighting set-up possible for their crop. Along with other specifications, growers should also consider wattage of LEDs required per square foot of their crop. This will help them determine number of LEDs required, placement of the fixture and spacing between the lighting systems. Typically, growers need a minimum of 30 watts per square foot to light an area. Example: If garden space is about 10 sq ft, the wattage can be calculated as 30 wattsx10 sq.ft = 300 watts/sq.ft. If optimal lighting is not provided to the crop, the yield will be low. Also, remember that using too much light or higher wattage would generate more heat and become a problem, too much heat will shrivel and damage the crop and cause unnecessary wastage of energy.