Giant moonflower is an annual shrub, and can be a root-hardy perennial in Maryland.  The plant is native to Mexico and the American southwest, Texas through California, and is considered a tropical perennial in those regions. 

I purchased a single plant several years ago with the though that we would enjoy the large, fragrant flowered night blooms near our hot-tub.  The single plant has grown to dozens and envelopes much of our backyard, up against the house.  The back of our house faces due south and is dry and hot during the growing season.