Does growing warmer hurt the flower quality?
Will growing at higher temperatures cause insects (spider mites, thrips, etc.) or powdery mildew to reproduce faster?
Many growers have concerns about running at the higher ambient temperatures we recommend, and we certainly understand them- but the short answer is that it does not cause problems under our PhytoMAX-2® LED grow lights.
Growing at 85 °F under HPS lights will usually cause heat stress to the plants and decrease yields, while at the same time evaporating off compounds like terpenes, giving a lower-quality harvest. Experienced growers are also aware that warmer temperatures make insects and powdery mildew reproduce faster- at least compared to the same growing setup kept at lower temperatures. These issues cause seasoned growers concern when we recommend running ambient temperatures in the 85-88 °F range.
To understand why these issues do not apply to plants grown under our Phyto-Genesis Spectrum®, it is important to re-examine why we recommend warmer temperatures with our lights in the first place. The spectrum of our lights is designed to nourish plants as efficiently as possible and does not heat up leaves as much as HPS or other light spectrums. Increasing the ambient temperature by about 10 °F / 5 °C is required to get the leaves themselves to be the same temperature as they would be under HPS lights.
Because the leaves themselves are the same temperature, things like terpenes will evaporate out of the leaves at exactly the same rate, whether the ambient air temperature is 75 °F under HPS lights or 85 °F under Black Dog LED lights. Things living on the surface of the leaves will also be the same temperature- so powdery mildew and spider mites will be at the same temperature whether the ambient air temperature is 75 °F under HPS lights or 85 °F under Black Dog LED lights. This is verifiable using a forward-looking infrared camera, as we have done in our study of spectral effects on leaf surface temperature.
To test our lights, we grow plants with them- a lot of plants. Spider mites occasionally get introduced to our research growing areas, as often happens if you have lots of people visiting the grow. Spider mite infestations are easily controlled and eradicated in our growing areas even though the ambient air temperatures when the lights are on are kept at 85-88 °F. In fact, it seems easier to eradicate spider mites on plants under our lights (even at 85 °F) because the UV light in our Phyto-Genesis Spectrum is a natural suppressant for insects and mites. We've never had powdery mildew bother any of our indoor gardens under Black Dog LED lights at any ambient air temperature, although it has grown on plants under lights lacking UV in the spectrum.
We have many years of experience growing plants under our lights at the ambient temperatures we recommend, and can assure you that the higher temperatures do not make insect, mite or mold infestations worse than they would be under HPS lights at 75 °F ambient air temperature. The UV in our spectrum actually suppresses infestations and makes them easier to control.