23. TEMPERATURE AND HUMIDITY

Temperature should be about 28 degrees Celsius but never higher than 32 degrees and never lower than 17 degrees. Furthermore, prevent temperature to drop or rise more than 10 degrees, this will give too much stress to the plant. With temperatures over 32 degrees the buds will get fluffy while very little THC is produced. If temperature drops under 17 degrees, plants will stop growing and stems will turn purple while buds will stay very small. Strangely enough, low temperature will give high THC percentage. 

Keep relative humidity between 50 and 60%. For making clones a separate room, closet or can is needed with a humidity of 80% because clones do not yet have a developed root system. Make sure not to go over 60% humidity while growing or flowering because this will ruin the carbon filter. On the other hand, a too low relative humidity will stress the plants and ruin the harvest. If necessary a water machine can be placed to improve the humidity. At the end of the harvest humidity level should be as low as possible to prevent bud rot. 

It is said, growing with use of extra CO2 can be done with higher temperatures. Personally, I think it is best to keep temperatures normal, this will give a good quality with high THC percentage while blooming with high temperature will give big buds but of a lesser quality. See also chapters 22, 21, 17 and 6.