I have two bonsai trees; a Desert Rose, which I've had for 15 years and a miniature Jade, which I've had for three. Both thrive outside during the growing season; both lose their leaves and slow way down indoors during the winter. (We are in southern New Jersey, about eight miles from the ocean.) I'm thinking about using grow lights this year, thinking that they may keep the trees happier during the winter. I'm looking for the guidance from the group here. What is your experience with grow lights. If you've had success with one brand or model, please tell me about it. 

Perhaps check here:  www.bonsaiempire.com/forum/tools/22716-r...or-grow-lights#86600

Desert roses is decidious in nature and yearly leaf drop is to be expected.

Jades never lose leafs in winter under the right care. I live in Sweden where days is less than 6 hours long in winter and almost always cloudy. My crassulas do not have any grow light and are doing fine without any abnormal leaf drop. I think watering is your issue, not light.

Using grow lights is not wrong for these species, just not needed. And low light conditions is not the reason for your trees dropping leafs. With that beeing said. There is another active thread right now discussing grow light. Read that so we do not need to repeat ourselves.