What is the coldest temperature a Norfolk Island Pine can withstand?

45-50 degrees

I'd say about the same as Janet said. If they go much colder they will suffer with susceptibility to pests & fungus because you have weakened their own immunities. They can tolerate a lot, but going too cold isn't good. If you have to move them to another location & it is cold outside, then wrap in a blanket as well as you can, have a warm car ready & move it. But never put the, outside to live as they are meant for inside.

These trees do not like temperature extremes, and will not survive temperatures much below 35 F (2 C) or above 85 F (24 C). The ideal daytime temperature is about 65 F (16 C). The perfect nighttime temperature is slightly cooler, around 55 F (13 C).

ive had trees survive 27 with no damage. I’d say 25 or below will damage or maybe kill it.

I live in St. Louis mo and I have Norfolk pine I have it inside. We had a very gold winter hence I ran heat alit. Woukd it be better if I put it in basement under grow light where it is cooler. ?

I had a small one in a pot left outside with a low of 25f overnight which was the coldest day of the year where I live in inland Southern California and there was no damage. A few years ago in another town I lived in a local Walmart had them outside and there was an overnight low of 21 and all the little trees had frozen growth buds. The problem with these trees if the growth buds are damaged they take a long to come back and generally the tree may have some deformities because of it. I don’t believe any Norfolk pines not even large mature trees will survive below 19 and that would have to be record cold.

I just recently got a 10-ft I believe it's in Norfolk pine and I'm going to keep it on my back porch and I want to make sure that it doesn't get too cold I have heaters out there so what I might do soon as the winter months come I'll set it at like 55°I will that be okay