The ideal temperature range for growing Cannabis.

The ideal temperatures for growing cannabis plants

There are a lot of fine details that a cannabis grower needs to pay attention to throughout the growing process, especially if the grower wants to see the best results possible and who does not want that? One of those core details in regards to growing is temperature.

There are many theories on the best temperature for cannabis growing and generally the consensus is anywhere in the 70-85°F or 20-30°C range. 85°F or 30°C would be the absolute highest temperature with an ideal range more in the 70-80°F or 20-27°C.

Warm it up in the vegetative stage

The temperature in the growing or vegetative stage needs to be a bit warmer than in the fruiting stage. So the 70-85°F or 20-30°C range is perfect for this stage. A general rule of thumb is that if you are really hot in the room where your growing, the plants are hot. If you are cold in the room, the plants are cold too. For the most part we like the same comfortable temperatures as the cannabis plants do.

Cool it down in the fruiting stage

In this stage the temperature is best if brought down a bit. Plants producing buds in this stage like the temperatures a bit lower for ideal results. During both stages the temperature during the day should be about 10 degrees warmer than the temperature at night; this is very important in the flowering stage. So in this stage the best range is 70-80*F (21-27*C).

What is the big deal?

Temperature is extremely important and can make or break the grow. Just like too much or too little water can hurt a plant, so can too high or too low of a temperature.

Brrrrrr!

Cold temperatures slow down growth immensely. Temps lower than 60°F/15°C will create problems with plant growth and freezing temperatures will kill the plants. Lower temperatures make room for outside invaders like molds, which can harm the plant. So it is best to never let your plant dip down into the lower temperatures.

Too hot to handle

When the temperature gets too high, it is bad news for plant growth. Usually it will not kill the plant, but growth will be extremely slow. Too much heat can cause spider mites, mildew, root rotting, burning, stretching, wilting and reduced aromas. So obviously these are not fun to deal with, so don't let it get too hot.

Adding some CO2 enrichment changes optimal temperatures

Cannabis can like higher temperatures when you supplement extra CO2, but make sure you seal the room, provide more light than normal and keep the temperature between 85°F/30°C and 95°F/35°C.

How to control your temperatures

Get a thermometer, then do what you need to make the temperatures stay within the optimal temperatures in the growing area. Make sure you use your head, don't use fire or dangerous substances. Keep it safe and keep it simple.

The bottom line

Cannabis plants enjoy a temperature range that is comfortable and easily manageable. If those temperature ranges are not carefully controlled though, the plant's final results will suffer. So have an accurate thermometer and keep a close eye on it.