If the foliage looks damaged I'd cut the vines back. The power went out in my GH and mine froze. I cut the stems back almost to the soil and they're putting out lots of new growth. As long as the roots didn't freeze it shouldn't be a problem. I have to cut them back to get them inside every fall anyway and have never had a problem with them growing back.
Karyn

I went ahead and cut it back to about 10", the leaves were dried out, but I noticed a little one inch sprout coming out from the base. It just makes me sick because it was about three feet tall, doing great and still shooting out runners off the top and best of all - it made it thru the winter in the garage. It's in a container with a tellis, I was having to take the runners and wrap them around it because they didn't have anywhere else to go.
This is my first year growing this and within the next month hoping to get it outside in the sunlight more.

Are they fast growers?

Can I take cuttings to start more?

If I was to take it out of the pot at this stage and break up the main root to start more, would it kill the plants?

I don't want to lose it, it WAS a beautiful plant last fall.

Any help from those that have been there would really be appreciated.

Michael

I wouldn't say they are particularly fast, more average. It will reach several feet in a fairly short amount of time once it warms up and it can go outside. I wouldn't unpot it and start trying to cut the roots apart unless you know for sure there's more then one plant in the container. The only way I've been able to propagate a mandevilla is by layering it.
Karyn