They can be fairly happy down to 45 or 40 degrees F. You can even leave them outside to lower temps assuming there won't be a frost or freeze but I don't recommend it.

lowest in pot 32F in ground just light light frost .

.... and so what happens, please, when we hit an unusual 25 degrees? My Rose of Sharon (second year) was about 2 and a half feet tall - I never pruned it and it was looking absolutely beautiful UNTIL we hit a record low of 25 last night. It was covered, but not enough because the leaves were all wilted and really damaged. Do I cut it back? Give up on it? Thanks - (really confused about hibiscus)

Carrie

Rose of Sharon is hardy way below 25 degrees, we grow them here where it gets down to zero occasionally. If it was an established plant already, it should put out some new leaves and be fine. I would wait until you're sure it's warmed up for good, then prune off just the damaged parts.

Great - I got the Rose of Sharon brand new last year, but no tag (it was discounted)... and just the other day it was all leafed out and looking beautiful - now all the leaves are wilted and awful looking. Will they just drop off and form new ones? If that's what happens, that will be good news. I am just learning about these shrubs.

Thanks

Carrie