Temperature plays a large part in having healthy mature cannabis plants, while they can stand low temperatures and high, they do best with a constant temperature. At low temperatures of around 32 degrees, or high temperatures of as high as 100 degrees, the marijuana plant will survive, however these temperatures will affect the photo synthesis process. That means the marijuana will not have the desired effect when smoked and when growing, the grower will battle things such as thin stems and other problems. The optimum temperature for having a healthy large yielding cannabis crop is between 70 and 75 degrees.