I've tried many times to grow a moonflower vine from seeds. Never any luck. They just would not come up. Finally this year I got some vines, and now even a couple of flowers! I took the photos, below, one bud is ready to open this evening, and one flower was tired and fading from being open all last night. This vine is growing in a pot with a small Japanese maple tree.
I don't know why they grew this year...? Was it the heat? The drought? I don't know but I am happy to finally see some of these gorgeous big blooms.