Hello, it has dropped to about 34 degrees at night here in Las Vegas NV. Cold desert evenings. I have a Chinese Elm which the leaves has turned colors, brown and redish. And a Gum tree which dropped all of its leaves. 

Should I bring them indoors for the winter or leave them on the patio? Should I water only when the soil gets almost dry?

Thanks for your help.

Chinese elm is a temperate tree and should be outdoors all year in zone 7 or above. The only risk I see is that it may not get cold enough or long enough winter for perfect health.