Depends what they are. My trees are not in bonsai pots, but 2ish gallon pots. Pines stay out all winter, JMs come in for a few weeks in mid Jan-Feb when (overnight) temps get below freezing temps for a week or so straight or a stretch of days of teens to single digits. Triopicals when overnight temps dip below 50F, but usually go out in the day if its supposed to be over 50.

Be sure to take wind chill into those equations as well.

Yeah, I'm trying to avoid the whole shuffling in and out thing. The nights have been in the 40's and 50's, but a couple nights, like last night, was in the mid 30's.

I'm assuming my most cold sensitive plants are my Adenium Obesum and Schefflera. I moved my schefflera and favorite adenium inside already. I had my ficus benjamina and retusa inside last night, but back outside this morning. They will probably move in for the winter on Saturday, which is unfortunate because my benjamina just started growing some aerial roots - I'll need to find a plastic jar to cover it.

My Jade are out there, and I will probably try to keep them outside until there is risk of frost. My california red tip is about to flower and I don't want to disrupt that with frost or a stress of moving it inside. My other jade is a compacta, supposedly Crosby, and I want to see if I can coax out some interesting colors with the temperature stress.

I will probably leave my ficus caricas and crepe myrtles out a bit longer since they need a winter dormancy anyway.

I'm interested in others' opinions because some people suggest to keep them all outside until frost, while I've heard temperatures below 50 can cause stunted growth or worse for certain tropicals (schefflera). I used to live in an area where I couldn't leave my plants outside because I was worried about theft or vandalism, so I'm trying to get a sense of what others do.