What is the ideal temperature and humidity for growing tents? The environmental conditions required for each stage of the plant are somewhat different, and there is no environmental condition suitable for all stages of plant growth. If you don’t have much time to take care of and don’t care about maximizing the harvest, you can always keep the temperature around 80°F. Seedling stage: 75°-85° Fahrenheit / about 70% humidity; Plant stage: 70°-85° Fahrenheit / about 40% humidity (no more than 55%); Flowering period: 65° – 80° Fahrenheit / 40% humidity (no more than 50%).