They can take full sun, and will probably be healthier and less leggy if you move them out of the shade. They're native to Mexico, and you see them there flowering on the roadsides at 12ft. tall, with no care whatsoever.
Just be sure to water a bit more as the plant grows if it's in full sun so it will make big, lush leaves. They grow in gardens here as well, but are subject to some fungal diseases so if they're in a crowded shrub border they tend to die out. Need great air circulation in our humid summers.
