Transition from HPS to LED – A Guide from Global Air Supplies
LED lighting is the future of indoor growing.
As pressure mounts for cultivators to embrace energy efficiency, more are making the switch from HPS to LED technology.
Adjust temperature when growing with LED
Growers familiar with cultivating under HPS light know that their fixtures emit a significant amount of radiant heat—the sort of heat that warms up the upper foliage of your crops. Excess radiant heat can damage your crop. But, when using HPS lighting at the manufacturer’s recommended mounting height and intensity, radiant heat can be also beneficial.
Use VPD as your management tool
In addition to monitoring and adjusting room temperature, it’s important to balance the other conditions, like moisture, in your space with a practice like VPD (vapor pressure deficit). Doing so can help promote maximum growth.
Factor in HVAC and Dehumidification
When switching from HPS to LED, an important consideration is dehumidification. LEDs are usually more efficient than HPS at converting electrical energy into light energy. Typically, this means growers can save on their energy bills and their rooms will require less cooling to maintain optimum growing conditions and high light levels.
Consider light spectra and light intensity on crop growth
Aim for a Balanced Light Spectra:
HPS lighting emits a lighting spectrum dominant in far red, red and yellow wavelengths of light. A red dominant spectrum like this can cause plants to grow taller and develop thinner stems and leaves as compared to natural sunlight. Natural light is thought to be more “balanced” due to more ultraviolet (UV), blue and green wavelengths.
Rich in blue, green, yellow and red light, LEDs can provide a more balanced lighting spectrum than HPS. Crops grown under the balanced spectrum of an LED exhibit growth patterns more true to crops grown under natural sunlight than those grown with HPS lighting. The result is crops that are stockier, with thick stems
and expansive, broad leaves.
Monitor and adjust nutrition and irrigation based on transpiration
It’s a common misconception that switching from HPS to LED automatically triggers a need for increased nutrient and irrigation events. It’s true, under ideal conditions, higher PPFD levels (as are possible with LED light) generally lead to faster growth, and thus an increased need for nutrients and water.
But more often, nutrient needs increase because growers do not adjust the other room parameters, like ambient temperature, VPD and dehumidification (as outlined in steps 1-4)—not strictly because of higher PPFD levels.