I got a Chinese Elm yesterday and I was wondering if it is ok for me to place it outside. I live in the US in Philadelphia, and the weather has been pretty cold lately. I also have 2 ficus ginsengs that I am unsure about if I should place them outside. I've been keeping them inside next to a full sun south facing window since the weather reached freezing.

"Pretty cold" is a term dependent on ones location. In italy it may be 10 degrees but where I live it is -10 degrees. Please quantify your temperatures. If it is above frezing it is safe to move chinese elm outdoors. For ficus it needs to be over 10 degrees.

Thanks for the reply! Right now it is 14, and over the next few weeks it will fluctuate between a high of 21 and a low of -1. Tonight it will go to 3 so I moved all the plants inside. I'm not sure if the constant change of environment is good for the plants...

I was also forced to repot one of the ficus ginseng since the pot broke

Do not move plants in and out on a daily basis. The elms are very hardy and should be outdoors all year if you are in usda zone 8 or higher. Since philadelphia is in zone 7 you will need to protect it some way in the coldest days. A cold frame, shed or greenhouse will do. Never ever in livingroom temperature in winter.

The ficus needs to be indoors in winter. For this species the issue is light and humidity.