For those interested in learning more about the science behind this, there is a term used by greenhouse growers known as VPD or “Vapour Pressure Deficit,” which roughly measures the temperature and relative humidity.
Colder temps will tend to slow down growth. Temps lower than 60°F (15°C) tend to upset plant growth, and freezing temperatures will shock or even kill a cannabis plant. Some plants continue growing in the cold without signs of stress, but they often don’t yield as well as they should given the amount of light they receive.
For example, Warm air can “hold” more evaporated water than cool air
With a properly insulated grow box, your grow lights will likely provide enough heat to keep your cannabis plants warm unless you live in a freezing cold area, or perhaps if you’re in the middle of winter or a cold spell.
Cannabis plants like a temperature similar to humans, or a little warmer – not too dry, not too humid.
Then you can buy rolls of insulating materials for cheap at your local home improvement store and use these to insulate your grow area further. Insulation will help keep the cold air out, and the hot air inside.
Why Temperature Matters to YOU As a Grower
Seedling & Vegetative Stage
Too Hot: What to Do
Learn exactly how to maintain the rigth temperature for your indoor cannabis grow room.