windows open as the cold may stunt growth. Just
refresh the air in your room for 15 - 20
minutes during winter and close it again.
If your grow is enclosed, then use fans to
extract the old air and another fan intake to
refresh the system.
HUMIDITY
Cannabis plants work best in the 40 - 80
percent relative humidity area. rH (relative
humidity) is the amount of water in the air.
Fresh air always is the best way to control
humidity. If you have a rH measuring kit you
can judge for yourself how much fresh air you
need before hitting the optimum 60% level.
There are some expensive devices called De-
humidifiers that control humidity in the room.
This is not recommended unless you have a very
large grow area underway. Just use fresh air
and you can't go wrong.
TEMPERATURE
Temperature is controlled by any heating
unit or natural sunlight that your room
receives. Normal households have suitable
