How the lights are designed will dictate what happens to the heat they generate.   Direct excessive heat from grow lights onto cannabis plants will damage or stress out the plants as well as dictate the overall health of plants.

Too much grow light heat will also produce powdery mildew which will rob the cannabis plants of water and nutrients. The plants weaken and flower production declines.

High temperatures and humidity can create conditions favorable for pest infestations.  Pests like spider mites, will extract fluids from plant cells reducing the plant’s overall health making them more susceptible to other stressors like diseases.

High temperatures can also lead to a decrease in yield diverting its energy away from growth and bud development to defend against the pests.

Next, too much heat from the light will also cause water to evaporate from your plant’s soil more quickly which can lead to nutrient burn which in turn will cause damage to the plant’s roots and foliage.  High temperatures in the root zone can negatively impact nutrient absorption and microbial activity in the soil, affecting overall plant health.

Then you have the degradation of the LEDs themselves: When LEDs get too hot, their efficiency or light output decreases while using the same amount of electricity, resulting in you turning them up to compensate for the degradation thereby consuming more power—–again, does that make sense? It will ultimately result in shortening the life of the LEDs.

Most importantly, LED degradation eventually will result color changing or color shifting… meaning  your proven spectrum, or the cornerstone of your profitability,  is going to change.

What’s happening is the LEDs are coated with various phosphors which helps to create a spectrum to mimic sunlight. Excessive heat also burns off the phosphors, causing color changing or shifting. While this might not matter much for parking lot lighting, roadways, or other non-horticulture it’s crucial for your grow operation, as your plants rely on a proven spectrum for optimal growth.