Andi,

I have also added Christmas lights to quite a few of my plants. I would be careful not to place the bulbs directly on the leaves. If you wrap around the stems or branches,it should be ok. I think when the bulbs rest directly on the leaves over a period of time, there will be some damage expected. But, the Christmas lights are a quick way to help to bring up the temp a little bit. Hope your plants survive your Winter there.

I put the bulb on when it was 24f directy on everything. it was probably cold enough that the bulbs wouldn't burn. I'll keep the bulbs on the stem when it's not a freeze.

tone sweetheart did ok. very little damage and a showing growth on some of the undamaged branches.

the mauritius I just up potted in the fall was flushing during the freeze and one entire side lost all its leaves. the other size many of the leaves show mild damage but didn't fall off.

it was my experiment to see how cold they could tolerate because I was considering putting them in the ground but after this hard freeze and seeing other unprotected plants take heavy damage I'm probably keeping them in pots and moving them to the garage or use a pop up greenhouse