What is the lowest-light plant that will also tolerate temperatures down to (but not necessarily below) freezing?

Lichen?You can find it out on the tundra…;)

@lucillelucillelucille: Do you have instructions on how to grow Lichen indoors (which is both a plant and fungus) or even where to order live Lichen?

Dracaena Marginata is one Dracaena that will handle the cooler temperatures. The marginata can generally thrive on temps as low as 40 degrees.

Kentia Palm – would thrive down to the 40’s as well

Cast Iron Plant – Aspidistra elatior can handle a very wide range of temperatures, 70–80’s down into the 30 degree range.

Rhapis excelsa – The “Lady Palm”, very similar to the temperature range of the Aspidistra. A slow grower but very sturdy.

No,but maybe a group like the Sierra Club might—I think that is the name—

@lucillelucillelucille don’t you wish you read and understand the actual post? It does state: This plant must live in an unheated building.

Why must you have a plant in an unheated building?

@faye: Of course no one growing an ornamental plant “must have” it. (be it outdoors, indoors, heated or unheated.) Is there something I do not understand about your question?

@njnyjobs: Thanks again. I have decided to start with the “Cast Iron Plant” since the link below states “It is the most cold-tolerant of any houseplant.”

http://www.plants-unlimited.com/index.cfm?fuseaction=browse&id=514623&pageid=174

You said the plant must live in an unheated building. I just wonder why.

@faye:
a) I own a building.
b) It is not heated.
c) I intend to put one or more plants into this building.
d) I do not wish them to die.

Are people going to live with this plant or will it just be one lonely plant facing the world? And still I wonder why?

Moss & Lichen enjoy that type of environment… not very attractive plants tho.

@Cloverfield: I do not think Moss & Lichen would be a good fit. The moss requires high humidity and the lichen is too small (if nothing else).

@faye:
a) Why what? Are you asking why people keep plants? http://besthomenews.com/6-reasons-to-have-plants-at-home/
b) It will be multiple plants.