Discover cold hardy plants for a green roof. Here, garden experts share their top 5 picks of low-effort, cold hardy plants to create a green roof that lasts.

. Q. I hate to still keep you on the "cold roof" subject, but I want to make a cold roof on my 6,000 square foot Victorian 4-unit with 2 furnaces that are located in the attic. What can I do? K.C.