Here in Colorado (high desert, Zone 6), my experience has been that
moonflowers don't need any encouragement. The lady that we bought our
house from had planted moonflowers and they became quite invasive. It
took about 5 years for me to irradicate them, and even now after 15
years, I still occasionally see one pop up.
Assuming we are talking about the same variety, I'd advise caution.
Gary