· John Heider's Answer
· Melissa-The Sun Parasol Mandevilla is not resistant to frost. Its hardiness zones are 9-11. Some say it will endure temperatures as low as 20 F, but I wouldn't want to try mine in that cool a temperature. Some in cooler zones will prune their plants back and overwinter indoors and return them outside after the last frost in early spring. I'm hoping your plant is ok, but it is possible any frost may have damaged your plant. It is possible it may sprout out yet. You can scratch a small spot on the stems with your fingernail or knife to see if there is green color under the bark. If it is brown that portion of the stem is dead. Many prune their mandevilla down to within six inches of the ground every few years in order to renew their plant. The mandevilla is fast growing and recovers from heavy pruning quickly.
I would check to see if the stems are stil living and if so you can prune out only the dead growth or down to withing 6 inches of the ground. In a few weeks with this warm weather you should see new growth if it is going to make it.
Many areas have had a lot of rain this year. Make sure your plant is in well drained soil. They like to be moist not wet. They are not tolerant of frost or saturated soils.
Hope this has helped.)