Meet my Grandpa Ott morning glory. He is cussedly persistant about coming back every year and trying to take over certain areas of my fence. I generally let him have his way in some places because he's so healthy. His blooms are deep purple that my camera doesn't capture well.
The plant is vigorous and deep green. I don't give it any care. Volunteers are sure to come up year after year, so you have to keep them thinned. If you want a non-invasive morning glory, then I recommend Heavenly Blue - I've never had one of them come up volunteer.
Though I sometimes get angry with this cantankerous old cuss, I generally let him have his way so he can bloom away without interference. He blooms in the deep summer when few other's are, so that makes up for his misbehavior.