Hi Gardener, you might wanna cover them real well if you get temps to -5, i have used bales of straw here in pa. good luck

Ken,
Thank You for the information. I grow a couple of bamboo that are only hardy to 5 degrees and they do Ok. But I think I'll try the greenhouse maybe inside another greenhouse. That should keep it safe.

Here is a link that might be useful: Gabelmans Gardens blog

yes gardener, doubling up on the greenhouses sounds like that would work well., just curious but what temps do you get inside the greenhouse in middle of winter with out heat, i may be tempted to try that. thanks