is hypertufa realy freeze/thaw proof?

can hypertufa be left settind on the ground or must it

have legs or somthing to keep it from tuching the ground

I have been reading about hypertufa for some time now and I

would like to tru to make some rocks and troughs but dont want to store them indoors in the winter.

My husband has been in the concrete business for about 30 years and he seems to think that hypertufa should be ok out side

I would realy like to try some things with hypertufa but dont want to put all that time in somthing that is only going to last for a year or two.

thanks for any help you can give