Matt, have you overwintered other tropical plants in your greenhouse for the whole duration of the winter in the past and how low did the temps go?

Many types of citrus will tolerate -3 C for a short time, though anything below -2C and fruit loss becomes likely.

sunshine, yes I keep lots of things in there.

Last winter I did the same thing but no citrus was planted. -3 C was the lowest temp which hit on Christmas eve 2017 and a few days after.. I got scared and dug them up, not this year lol.

This is a pic from Feb 2018

February is the start of spring in there.

Matt, your Banana tree actually takes the cold like that?

Mines will not tolerate anything below 55 degrees. The leaves will die back. As long as the ground does not freeze in there, all your citrus should do just fine. Mine are constanly exposed to the 30's and they don't object at all. in fact, they fuss when temps rise above the 55 dgree mark in winter..Crazy

Your spring starts that early? Mine does not start until April.

Mike