Ipomoea tricolor. It is a great shame that so many gardeners confuse this tidy heirloom annual with the invasive weed Convovulus arvensis. Both share the name Morning Glory, and both have trumpet shaped flowers, but the similarities end there. Heavenly Blue morning glory seeds produce short vines bearing copious, huge, intensely blue flowers that open each morning and then fade to pink before closing for good in the evening. Every day more flowers open from mid to late summer. It looks spectacular climbing along a fence or trellis, with really large flowers that can only be described as Heavenly Blue.
Note: This variety is not an invasive weed.