to raise the humidity first try using a bucket of warm water, or get a humidifyer.

the more surface area the water has and the closer it is to light and heat the faster it will evaporate and should raise the humidity abit for you

hope this helps any
texas grass Reviewed by texas grass on . Grow box humidity????? Hey folks, I've built a box with a 600 w air cooled hps and a substantial ventilation system. I can keep the box in the upper 70's but the humidity is running about 20% due to the amount of airflow. About 160 cfm in and 100 cfm out. This is my first grow and the plants are about 3 weeks and seeming to love the light. Won't the humidity climb as the plants grow? and do I have any worries with the current levels?? Thanks! :cool: Farmer Rich Rating: 5