Introducing LED Bulbs to Hydroponic Gardening Systems

By: Charlene Rennick

Although the jury is still out on whether or not LED bulbs are a confirmed improvement over regular hydroponic grow lights, currently the LED bulbs have several distinct and known advantages. 

In the absence of side by side testing against Metal Halide and High Pressure Sodium bulbs, some benefits of substituting LED bulbs can be appreciated in a hydroponic garden. 

LED bulbs:

• are green; they do not produce much heat and consume less energy
• require less energy spent on ventilation because their light is not hot
• do not need a ballast or an external igniter for the ballast
• are direction-focused and don’t need a reflector
• produce less noise
• give approximately 18 hours of light per day for 7 ½ years
• can be used for multiple plant species simultaneously
• will not scorch seedlings or delicate plants
• come in a wide range of colour in the spectrum

Important Points to Consider

There is still some unknown ground to cover using LED bulbs in hydroponic growing systems.  It is not as simple as switching only the light source.  The effects of LED technology on the rest of the hydroponic system must be included when considering the advantages.  Because LED light is cooler, evaporation and transpiration rates will be much slower and the nutrient solution will not have to be added as often.  The climate controls will have to be adjusted to take the cooler LED bulbs into account.  If you live in a colder climate, there will be less heat generated from LED bulbs, so you may need to add a heat source in the winter.  The plants might grow at a different rate.  Close observation of your plants and hydroponic system will be necessary to help you determine what adjustments will optimize your plant growth.   

Choosing an LED Bulb

Lumens and Lux are terms that measure light source brightness as it appears to a human eye.  The degree of Lumens or Lux cannot accurately describe the effect of an LED bulb on plant growth.  The best measurement would be described in photons, which carry electromagnetic radiation and measure the frequency of light energy in a given area per second. Some colours of light have a higher concentration of photons, so it is important to know the colour composition of the LED bulb and the photon composition of the spectrum in order to measure the efficiency of the LED bulb.

The economic savings of LED light sources are obviously advantageous.  The long-range effects on plant growth and the hydroponic system as a whole are yet to be conclusive.