When the blue blossoms of Baptisia fade, a gap of colorless space is left in the perennial garden. To remedy this, I use morning glories to fill in where Baptisia left off.
Beware - you have to keep this annual under control. Morning glory has much ambition and will dominate an area if left unchecked. Allow her to casually ramble among your Spring-blooming perennials during Summer, but keep her pruned back to prevent her from strangling the other plants.
Morning glory will reseed year after year and become even more ambitious in the process. Be sure to thin out the vines when they are young, as they can be difficult to remove when long strands have wrapped around each other and anything else in the vicinity.
I have never actually sowed a morning glory seed. This plant was transplanted from volunteers that sprung up three years ago in the front yard. I suppose a bird "put" it there!