Where do you live? This is in a pot, right? My key lime doesn't seem to care for temps in 30s, so I try to move it in when temps get into low 40s. It still drops some leaves.

I was referring to containers, yes.

All my citrus stays out until the mid to low 30's, none of them seem to mind and my Bearss was much hardier than my Meyer last year and took to the cold much better. This year I have 5 lime varieties and all of them have been out with the dips/light frosts into 34-36 degrees at night and 50-60's in the day and been just fine, half of them even have new growth that hasn't been damaged. Mine are in a slightly protected location so that may help with wind chill being less of an issue, I say just keep an eye and see when the tree starts to look stressed but mid 30's shouldn't be a problem.

Silica, you should tell that to half my trees that are pushing new undamaged growth now. All I can think of is that since the lows are at night and the days get above 50 is why they are still actively growing. Once my day temps are consistency lower the that's when the trees come in. In my personal experience with my trees is that they grow better left out in the cold than they do in my warm garage/house with lights. By I may have some sort of Micro climate that i'm not factoring in since I have always grown my trees against a wall or a fence and that probably helps protect them from too much wind and radiate heat for them.

My Bearrs lime survives outside in the winter when temperatures occasionally get into the high 20s for a few hours. It does tend to have a lot of leaf drop, much more than any of the other, more cold tolerant citrus. My Meyer Lemon is WAY more cold tolerant than the Bearrs which is in line with the standard teaching that, in general, lemons are more cold tolerant than limes and Meyer is one of the most cold tolerant of the lemons.

-Brett

Sammers, what you write could well be true *IF* the combination of night lows and day highs averaged out keeps the average temperature above 52.4-F. However, when the average is below the absolute low then there is no growth.