Recommended LED Grow Room Temperatures
Growing with LED lights can be very different than growing with traditional HPS counterparts. LEDs run cool due to the fact that they emit light solely by the movement of electrons in a semiconductor, or as its known, the LED chip. Because of this, and the fact that an LED diode is so efficient, they run cool and don’t need a lot of extra equipment to cool them. It also means that very little energy goes unused, resulting in very little excess heat energy.
HPS on the other hand is a burning mix of Xenon, Mercury, and Sodium gases. This mixture of gas burns at extremely high temperatures in order to produce the massive amount of light that these bulbs emit. The issue with this massive amount of light is that much of it is wasted due to the low absorption rate of certain areas of the spectrum that are the highest energy output and ends up as nothing more than excess heat energy, and lots of it. That heat energy is then absorbed by the plants and results in unusable photons, which then translates into high surface temperatures on the leaves of plants.
The ambient temperature of the room also affects leaf surface temperatures. The surface of an HPS bulb can reach an excess of 750 degrees and can warm a room up fairly quickly, even if it’s being properly cooled.
The surface temperature of the leaf, and thus the internal temperature of the leaf, can have a huge effect on the rate in which the plant transpires. Transpiration is the mode in which plants control the movement of water out of small pores in the leaves’ surface called stomata. The release of this water vapor through the leaves’ surface is the plants way of not only regulating temperate, but is also the way the plant cycles water and is able to renew its moisture feed via the root system. Think of it as a wicking system. The water leaving the plant is what is creating the force for the roots to pull more in. So, a plant that has healthy transpiration, also has a healthy uptake of water through its root system. The healthier the uptake through the root system, the more nutrients the plant can absorb and utilized for rapid growth.
Transpiration is greatly affected by temperatures within the leaf. The cooler the temperature, the less the leaf will transpire. The warmer the temperature, the more it will transpire. Because the surface temps on a leaf of a LED lit room can average up to 12 degrees colder than a HPS lit room, transpiration can slow, and thus result in slower uptake by the roots and as a result slow growth rates.
Because of this, Kind LED strongly recommends raising the temperature of your grow room to 82-85 degrees when growing with our lights. This will ensure that the stomata of your plants can fully perform their job and also allow metabolic processes to continue uninhibited for robust growth.
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