Sorry, forgot to mention these are the vining type and not the bush kind.

"They are in the same place as the ones I had last year, so conditions are pretty much identical." Step back and try to think of any differences in plant growing pattern;- watering frequency, fertilizer change or different brand used. Often, observing the plants by comparing the internodes and leaves can give you a good idea. I believe Ipomoea actually bloom better with out too much fertilizer anyway.

Congratulations on your bud! Watch it closely; in my experience with my own moonflowers (the vine type) they open very quick. I actually saw one opening one time, in the span of about 30-45 seconds! Mine opened early evening, but I'm in MA, not CA. Good luck on catching it open! They're also the most fragrant when they first open, and it's just the most beautiful flower scent I've ever smelled. -Barbara

When the plants set alot of seedpods , it sends a signal to the plant that it doesn't need to produce more flowers , as much as finish developing the seeds...that is how the plants survive... You could try cutting off some or all of the seedpods and use some (phosphorus based) bloom booster...make sure you water the plants... There is no guarantee that the plants will resume flowering... There are some people who start plants at different times and this may allow some plants to continue to bloom after the 1st series has finished , although it is mostly the gradual shortening of the day-lengths that causes the initiation of flowering... You could start a whole new series of plants but will they have enough time to flower (?)...alternatively you could root cuttings from the current plants and provide the required care until they are ready to place outside and these cuttings may flower as it is the new root system that will allow the flowering...the old root system has already received signals from the seedpods that no new flowers are required... So , there's a variety of suggestions or at least info and some Food for Thought... regards, Ron