Q.Outdoor planting of a Mandevilla
I live in Vermont. Built a new porch which has a new patio, house side I have installed a trellis. NW corner of the house. Is is possible to plant a Mandevilla here at this time of year. Very protected area where the sun only gets to that part of the house after noon and fades by 3:30 behind the trees of the hill. More sunshine in the warmer weather seasons. Of course, there will be no foliage on those trees in a month. What do you think?

In your region, the plant will likely not return. These plants are normally treated as annuals when planted outdoors where winters drop below 50 degrees F. That said, if you don't mind replacing your mandevilla each year, they can remain outside. Otherwise, I would recommend bringing the plant inside over winter as opposed to planting them outdoors.