Can I keep them in my basement which gets limited light? Can I cut them back when wintering? I live in coastal Maine. If wintering is successful, when should they be brought out and fertilized?
Wintering Dipladenia Inside
Certified GKH Gardening Expert
This article has plenty of information on winter care for Dipladenia (a type of Mandevilla):
According to the article, you can either cut the plant back and then store in a low-light basement which is at about 55-60 degrees, or you can keep the plant as a houseplant through the winter.
In either case, you can fertilize and put the plant outside as soon as the danger of frost is past and the temperature is above 60 degrees most days. It looks like this would happen around mid-late May in coastal Maine.