Q. Can you share with me an article that Sonia Uyterhoeven wrote about overwintering Mandevilla splendens?
Sonia has not worked here in a long while. But I do have some information about Mandevilla,formerly called Dipladenia. It is a very easy plant to grow. and I have over-wintered it indoors quite easily. I now have it on my back porch, and have left for a ten day vacation recently. A friend water it just once while I was away. Along with kolanchoe another easy care plant I have few worries and nice flowering plants during the summer into fall.
More here: http://www.clemson.edu/extension/hgic/plants/landscape/groundcovers/hgic1109.html
Hope this helps.