Benjamina cold tolerance

I did some Google searches on the topic of Ficus benjamina but the answers vary. Some sites say the lower range (in Fahrenheit) is in 50's and some say 60's.
I thought that ice crystals puncturing the cell walls was the cause for frost damage. I was curious as to the biological process of how a temperature in the 40's could damage even a tropical plant.
I have a "mother" benjamina plant that is too big to do the "bonsai tango" with everyday, but it could use some real sunlight with nighttime temperatures dipping into the 40's for the next few weeks.

Thanks,
David

Ficus benjamina and most of our other bonsai figs can tolerate temperatures almost to freezing, but won't like it. I put my figs, and most tropicals, out when the temperatures go above 40-45, 4-7 C, and bring them in in the fall likewise. An occasional dip to 40 will not hurt.
There is more to cold damage than ice crystals. The tropicals have a metabolism geared to warmer temperatures.
Iris

I had one kept outside year round when I lived in Berkeley Ca. And when hit got below 50F, I'd get black spots on the leaves. Keep it above 50 and you're fine ime.

What Iris said. What I found is that it (40s) won't kill them but you will notice slow down in growth after.

If its only for a few hours during the night 40s and even mid 30s will be fine, ive done it a bunch. There was once a picture I saw (im not sure what forum or website) of someone in northern florida who had a sudden freeze come about and just like they do with strawberries and orange trees with late freezes they just set up a sprinkler system over the area during the coldest part of the night and their collection of ficus (mostly willowleaf) were completely encased in ice by morning. The grower said the trees did just fine afterwards.