I have had better luck with Camellias than Mandevilla. That is just me! They all went to plant heaven last summer due to lack of care on my part. Sorry, I am not much of an inspiration.

Camellias should be lush green during the winter here. The Genus is a rather large one. I assume some variation in their species may influence how well they may fare in our climate zone.

Mandevilla, mine loose all of their foliage then once the warmer weather begins so does their leaves. I grow it year around outdoors with mid day protection from our strong sun.