a dehumidifier is probably the best idea tho, If you have 70% humidity that is. Becuase well its better all around not just for the plants to lower the humidity in your house or where ever you are. Its a good investment and almost every basement should have one, keeps moisture and mold off the walls. Im lucky i had one already, if not my room in my basement where i pretty much live, would become very mildew like and smell just odd.