If you love morning glories, try this low-growing cousin, which has even more gorgeous sky blue flowers. Like the morning glory that grows upward, this more earthbound beauty produces striking blue flowers all season long. And like its cousin, the flowers tend to close in the afternoon hours. In Zones 8-11, in the warmest part of the country, this tropical is a perennial; farther north, it's grown as an annual. Its spreading habit is perfect for spilling over baskets, window boxes, and other containers.Plant established plants outdoors after all danger of frost has passed. Evolvulus likes rich, well-drained soil and needs just average water. It's somewhat drought-tolerant, so don't overwater.