I agree with Rockm, Humidity trays are useless. Humidifier in the room that the tree/s are kept in works best. I have a Brazilian rain tree, that likes to have some of its older leaves turn yellow and drop when inside during winter when the humidity was too low. I use to place in at one end the bath tub close the curtain and the bathroom door and turn the water on hot on the other side of the tub and let it get all steamy in there for a few minutes and then turn the water off and just let it sit there for a while. Worked great, just be sure there's no splash back from the hot water that hits the tree o you could have one seriously dead tree on your hands. Your best bet is to use a humidifier now which is mainly what i do.